Elephant Formulary
© 2003-17 Susan K. Mikota DVM and Donald C. Plumb, Pharm.D. Published by
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Ophthalmic Products
Ophthalmic Products Index
The following section lists the majority of veterinary-labeled ophthalmic topical products and some of the more commonly used human-labeled products in veterinary medicine. It was written in cooperation with Dennis K. Olivero, DVM, DACVO to whom I would like to express my gratitude. Drugs are listed by therapeutic class. All doses (in italics) are from Dr. Olivero, unless otherwise noted.
For additional information, an excellent review on veterinary ophthalmic pharmacology and therapeutics can be found in the chapter by A. Regnier and P.L. Toutain in: Veterinary Ophthalmology, 2nd Edition; Kirk N. Gelatt, Editor; Lea & Febiger, Philadelphia, 1991. 765 pp
Ophthalmic Products, Topical
Glaucoma, Topical Agents
Timolol Maleate Ophthalmic)
Metipranolol(Ophthalmic)
Levobunolol HCL(Ophthalmic)
Pilocarpine HCl (Ophthalmic)
Demecarium (Ophthalmic)
Epinephrine, Topical (Ophthalmic)
Dorzolamide HCl (Ophthalmic)
Latanoprost (Ophthalmic)
Vasoconstrictors/Mydriatics
Phenylephrine HCl (Ophthalmic)
Cycloplegic Mydriatics
Atropine Sulfate (Ophthalmic)
Tropicamide (Ophthalmic)
Topical Anesthetics
Proparacaine Hcl Ophthalmic)
Non-Steroidal Antiinflammatory Agents
Flurbiprofen Sodium (Ophthalmic)1
Ketorolac Tromethamine (Ophthalmic)
Diclofenac Sodium (Ophthalmic)
Antiinflammatory Mast Cell Stabilizers
Lodoxamine Tromethamine (Ophthalmic)1
Cromolyn Sodium (Ophthalmic)
Corticosteroids, Topical (Ophthalmic)
Antibiotics, Single and Combination Agents
Norfloxacin (Ophthalmic)
Ofloxacin (Ophthalmic)
Gentamicin (Ophthalmic)
Tobramycin (Ophthalmic)
Tetracycline (Ophthalmic)
Antibiotic Combinations
Antibiotic & Corticosteroid Combinations
Antifungals (Ophthalmic)
Natamycin (Ophthalmic)
Miconazole (Ophthalmic)
Silver Sulfadiazine (Ophthalmic)
Antivirals (Ophthalmic)
Trifluridine (Trifluorothymidine)
Cyclosporine (Ophthalmic)
Diagnostics
Fluorescein Sodium (Ophthalmic)1
Rose Bengal (Ophthalmic)
Glaucoma, Topical Agents
Note: Generally, once acute congestive primary glaucoma is noted in one eye it is treated as an emergency using mannitol/glycerin systemically, a systemic carbonic anhydrase inhibitor, a miotic and then surgery is considered for lasting control of intraocular pressure. The following topical drugs are used “in general” as a preventative measure to prevent the occurrence of primary glaucoma in the unaffected eye. Topical ocular antihypertensive medications are sometimes employed for pressure control with secondary glaucomas also.
Indications/Pharmacology – Timolol maleate is used primarily to prevent the development of primary glaucoma in the contralateral eye of a dog which has developed primary glaucoma in one eye. It only reduces intraocular pressure 3-10 mmHg and, therefore is of minimal usefulness in patients requiring treatment of primary acute congestive glaucoma. Timolol’s mechanism of action: decreases cyclic-AMP synthesis in non-pigmented ciliary epithelium resulting in decreased aqueous humor production. It may also cause slight miosis in dogs and cats.
Suggested Dosage/Precautions/Adverse Effects – One drop twice daily of the 0.5% solution. The 0.25% concentration has minimal efficacy in animals and is not worth using. While problems have rarely been noted in veterinary medicine, ophthalmic beta blockers should be used with caution in patients with bronchoconstrictive disease or congestive heart failure.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products: Timolol Maleate 0.25% (see dosage above) or 0.5% solution in 2.5, 5, 10, and 15 ml Ocumeter® bottles; Timoptic® (MSD); (Rx)
Indications/Pharmacology – Metipranolol HCl can be used as a substitute for timolol maleate (see above). Metipranolol is a nonselective beta blocking agent and reduces intraocular pressure minimally in animals by decreasing cyclic-AMP synthesis in the ciliary body. Pilot studies have suggested that metipranolol is as effective as timolol maleate, but is significantly less expensive. Metipranolol has been useful in the author’s (DKO) clinic for the management of primary open angle glaucoma in cats.
Suggested Dosage/Precautions/Adverse Effects – One drop twice daily of the 0.3% solution. While problems have rarely been noted in veterinary medicine, ophthalmic beta blockers should be used with caution in patients with bronchoconstrictive disease or congestive heart failure.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary Labeled Products: None
Human-Approved Products: 0.3% Metipranolol Solution in 2, 5, & 10 ml OptiPranolol ® (Bausch & Lomb); (Rx)
Indications/Pharmacology – Levobunolol HCl is a beta1 and beta2 blocking agent similar to timolol and metipranolol above but without the potential for myocardial depression or airway constriction noted rarely in veterinary medicine and occasionally in human patients. Levobunolol is used in humans with glaucoma responsive to beta adrenergic blocking agents but who suffer cardiac and respiratory side effects associated with timolol.
Suggested Dosage/Precautions/Adverse Effects – One drop twice daily of the 0.5% concentration. Miosis may develop in veterinary patients after application of topical beta blocking antiglaucoma medications.
Dosage Forms/Preparations/FDA Approval Status-
Veterinary Labeled Products: None
Human-Approved Products: Levobunolol HCl 0.25% or 0.5% solution in 5, 10, & 15ml. Betagan ® (Allergan); (Rx)
Indications/Pharmacology – Pilocarpine is a miotic agent that is used in the treatment of primary glaucoma only. Pilocarpine causes the ciliary body muscle to constrict placing posteriorly directed tension on the base of the iris to mechanically pull open the iridocorneal angle structures. By causing miosis, it may prevent closure of the iridocorneal angle by preventing excess iris tissue from peripherally compromising the outflow of aqueous humor.
The lacrimal glands of dogs and cats are predominately under parasympathetic stimulation. Pilocarpine was used in the 1970’s and early 1980’s as a stimulant of tear production, delivered either topically or by applying it (the eyedrop preparation) on the food of dogs with keratoconjunctivitis sicca. Toxicity problems with excessive salivation, vomiting and diarrhea complicated its use. It does not directly address the issue of autoimmunity thought to be the etiopathogenesis behind most cases of keratoconjunctivitis sicca in the dog. The popularity of treatment of KCS with ophthalmic cyclosporine ointment has been associated with a decline in the use of pilocarpine for this disease.
Suggested Dosage/Precautions/Adverse Effects – One drop in affected eye(s) 3 times daily. Usually 1% or 2% is most commonly used in veterinary medicine. Pilocarpine can cause local irritation initially. In humans, this irritation reportedly diminishes after 3 days of therapy. It may also cause inflammation of the uveal tract, especially with repeated applications and can cause hyphema. Pilocarpine should not be used in secondary glaucoma cases. With repeated use, pilocarpine may cause systemic effects (vomiting, diarrhea, and increased salivation).
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products:
Pilocarpine HCl Ophthalmic Solution 0.25%, 0.5%, 1%, 2%, 3%, 4%, and 6% (in addition there are 8% and 10% solutions and a 4% gel is available from Alcon) in 15 ml and 30 ml containers. There are many products and trade names associated with pilocarpine, including Isopto Carpine® (Alcon), Ocu-Carpine® (Iomed), Piloptic® (Optopics), Pilostat® (Bausch and Lomb) and many generically labeled products. All are Rx.
See also the epinephrine monograph for information on epinephrine/pilocarpine fixed dose combination products.
Indications/Pharmacology – Demecarium is a potent carbamate inhibitor that may reduce intraocular pressures for up to 48 hours in canines. Demecarium reversibly inhibits anticholinesterase thereby causing miosis. Demecarium is generally used in preventive management of the contralateral eye in patients after the diagnosis of an acute congestive crisis of primary glaucoma in the other eye. It is not used in secondary glaucoma. Demecarium has the advantage of once or twice daily dosing.
Suggested Dosage/Precautions/Adverse Effects – One drop once or twice daily. Demecarium is contraindicated during pregnancy. Because of additive effects, demecarium should be used with caution with other cholinesterase inhibitors (e.g., carbamate/organophosphate antiparasiticides), or succinylcholine. Demecarium may cause local inflammation and systemic adverse effects (vomiting, diarrhea, increased salivation, cardiac effects) are possible, particularly with high dosages or in very small dogs.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products:
Demecarium 0.125% or 0.25% in 5 ml dropper bottles, Humorsol ® (Merck); (Rx). Do not freeze and protect from heat.
Epinephrine, Topical (Ophthalmic)
Indications/Pharmacology – Epinephrine (usually in combination with pilocarpine due to epinephrine’s mydriatic effects) is usually used as a preventative measure to prevent glaucoma in the unaffected eye. Epinephrine acts on both alpha and beta adrenergic receptors, thereby causing conjunctival decongestion, transient mydriasis (less so in cats) and decreased IOP (intraocular pressure). Decreased IOP is probably due primarily to increased aqueous humor outflow, but decreased aqueous humor production may occur secondary to vasoconstriction.
Suggested Dosage/Precautions/Adverse Effects – One drop 2-3 times daily in the unaffected eye. Epinephrine may cause ocular discomfort upon instillation.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products:
Epinephrine (HCl) 0.25%, 0.5%, 1% & 2% in 10 or 15 ml btls.; Epifrin® (Allergan), Glaucon® (Alcon); (Rx)
Epinephrine (Borate) 0.5%, 1% & 2% in 7.5 ml btls; Eppy/N® (Pilkington/Barnes-Hind), Epinal® (Alcon); (Rx)
Epinephrine Bitartrate 1% in combination with Pilocarpine HCl (either 1%, 2%, 3%, 4% or 6%) E-Pilo-1® (2, 3, etc.) (Iolab); P1(2, 3, etc.)E1(Alcon); (Rx)
Indications/Pharmacology – Dorzolamide is often used in the contralateral eye of a dog with primary glaucoma to prevent development of bilateral disease. It is also an excellent agent to consider for most secondary glaucomas in dogs and cats because it has no effect on pupil size. Like the related oral carbonic anhydrase inhibitors (dichlorphenamide or Daranide®, methazolamide or Neptazane®), dorzolamide decreases aqueous humor production by the ciliary body epithelium by altering pH and affecting the H+/Na+ active transport exchange mechanism. Oral carbonic anhydrase inhibitors cause numerous systemic side effects such as metabolic acidosis and panting, diarrhea, vomiting, anorexia and others, all of which can be avoided with topical carbonic anhydrase inhibitors.
Suggested Dosage/Precautions/Adverse Effects – One drop three times daily is the standard treatment frequency, adjusted based on clinical response. Dorzolamide may cause stinging upon topical application.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products: Dorzolamide HCl 2% 5, 10, 15ml; Trusopt® (Merck); (Rx)
Indications/Pharmacology – Latanoprost is a prostaglandin F2alpha analogue which reduces intraocular pressure by increasing aqueous humor outflow via the uveoscleral outflow mechanism. The major outflow mechanism in animals and people is through the iridocorneal angle termed the conventional outflow mechanism. A species variable alternative pathway directly across the surface of the iris into the iridal venous supply accounts for some outflow in people and animals. The horse apparently has the highest uveoscleral outflow of the domestic species studied. Latanoprost dramatically increases uveoscleral outflow and is an exciting agent for glaucoma patients because this medication directly increases alternative drainage of aqueous humor, which logically would seem superior to reducing production or attempting to increase outflow through a failing conventional outflow system. Latanoprost is marketed for once daily usage in people and clinical studies show reduced effectiveness when once daily treatment is exceeded. In the author’s clinic (DKO) with limited cases, the intraocular pressure reduction associated with the use of this agent has been impressive and can exceed even that possible with oral or topical carbonic anhydrase inhibitors. Latanoprost has been used in veterinary ophthalmology to treat primary and secondary glaucomas although clinicians should assess the possibility of profound miosis associated with the use of this medication in their secondary glaucoma cases.
Suggested Dosage/Precautions/Adverse Effects – One drop is applied in the PM. Latanoprost may cause topical irritation. Conjunctival hyperemia is commonly noted in patients using this medication. A direct stimulation of iris melanocytes results in excess melanin production in the iris of people using this medication, causing a dark brown color change to the iris. Profound miosis is noted with the use of latanoprost in dogs and cats.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products: Latanoprost 0.005% 2.5 ml; Xalantan ® (Pharmacia & Upjohn) (Rx). Store under refrigeration until use; at room temp for 6 weeks after opened.
Vasoconstrictors/Mydriatics
Phenylephrine HCl (Ophthalmic)
Indications/Pharmacology – Phenylephrine is used to differentiate conjunctival vascular injection (blanches with phenylephrine application) versus deep episcleral injection (blanches incompletely) associated with uveitis, glaucoma, or scleritis. It is also used prior to conjunctival surgery to reduce hemorrhage and in combination with atropine prior to cataract or other intraocular surgeries which require maximal pupillary dilation. Phenylephrine can be used to confirm the diagnosis of Horner’s syndrome. Dilution of 2.5% phenylephrine solution with saline (1:10) produces a 0.25% solution. Normal eyes will not demonstrate mydriasis in response to this low concentration of phenylephrine. Third order Horner’s syndrome of greater than two weeks duration is associated with receptor up regulation and therefore a response to 0.25% phenylephrine is noted. In this way, the diagnosis of Horner’s is confirmed and a suggestion as to whether or not the condition is 2nd or 3rd order in nature.
In dogs, maximum mydriasis persists for about 2 hours and effects may last for up to 18 hours. Phenylephrine has significant alpha adrenergic effects (vasoconstriction and pupillary dilation) and minimal effects on beta receptors. When used alone, phenylephrine is reportedly not efficacious in the cat unless used with other mydriatics.
Suggested Dosage/Precautions/Adverse Effects – For diagnosis and characterization of Horner’s syndrome: Apply 0.25% solution (see above) in both eyes. If there is a response in the miotic eye; 3rd order. If no response, apply 2.5% solution; if there is a response in both eyes it confirms Horner’s and probably is 2nd order.
For treatment of Horner’s Syndrome: Treatment is indicated only if patient experiences visual difficulty because third eyelid is elevated over pupil; then given on an as needed basis with an average duration of effect of 3-6 hours.
Prior to cataract or intraocular surgery: 2.5% or 10% given every 15 minutes for two hours. Monitor for hypertension and/or cardiac arrhythmia in small patients especially when using the 10% solution.
Local discomfort may occur after instillation and chronic use may lead to inflammation. In some species (cat, rabbit, humans) transient stromal clouding may occur if used when corneal epithelium is damaged.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products:
Phenylephrine HCl 0.12% in 15 ml or 20 ml bottles (OTC)Phenylephrine
HCl 2.5% in 2, 5 or 15 ml bottles (Rx)
Phenylephrine HCl 10% available in 1, 2, 5 or 15 ml bottles (Rx). Available generically and under several proprietary names. A well known trade name is Neo-Synephrine® (Sanofi Winthrop). A viscous form of the 10% is also available.
Cycloplegic Mydriatics
Indications/Pharmacology – Atropine, when used topically on the eye, acts by blocking the cholinergic responses of the sphincter muscle of the iris and the ciliary body to cause mydriasis (pupillary dilation) and accommodation paralysis (cycloplegia). Atropine may be useful in the control of pain secondary to corneal and uveal disease; to maximally dilate the pupil prior to intraocular surgery; to dilate the pupil and prevent pupillary block in glaucoma and uveitis. In the dog, atropine causes maximal mydriasis in about 1 hour and it may persist for up to 120 hours. Cats also show a delayed onset of action and mydriasis may persist for up to 144 hours (dose dependent). Atropine is particularly long acting in horses.
Atropine may be used in combination with 10% phenylephrine to achieve mydriasis and cycloplegia in cases of anterior uveitis.
Suggested Dosages/Precautions/Adverse Effects – Ointments or drops are routinely used in dogs. One percent is commonly used, but 2% solutions may be required in severe cases of uveitis. Ointments are generally used in cats to prevent hypersalivation associated with the bitter taste of this medication. Dosage frequencies are variable depending on the condition and its severity. Commonly, atropine is given as one drop 2-3 times a day until pupillary dilation is achieved and once daily thereafter to maintain this response.
Atropine may precipitate acute, congestive primary glaucoma in dogs predisposed to primary glaucoma; do not use in primary glaucoma. Repeated topical application prior to surgery can result in systemic atropine toxicosis (mania, hyperthermia, etc.). Salivation may result in dogs as well as cats (see above) secondary to the bitter taste.
Reportedly, very frequent treatment with atropine may induce colic in horses secondary to systemic absorption and atropine’s vagal parasympathetic effects. However, clinically this effect is only rarely noted.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products:
Atropine Sulfate Ophthalmic Ointment 10 mg/gm (1%) in 3.5 gm tubes; (Schering-Plough); (Rx)
Atropine Sulfate Ophthalmic Ointment 10 mg/gm (1%) in 3.5 gm tubes; Atrophate® (Schering-Plough); (Rx)
Human-Approved Products:
Atropine Sulfate Ophthalmic Ointment 5 mg/gm (0.5%), 10 mg/gm (1%) in 3.5 gm tubes; Generic and various trade names; (Rx)
Atropine Sulfate Ophthalmic Solution 0.5%, 1%, and 2% in unit dose droppers; 2, 5, & 15 ml bottles; Generic and various trade names; (Rx)
Indications/Pharmacology – Tropicamide, like atropine, causes mydriasis and cycloplegia, but has more mydriatic than cycloplegic activity. Tropicamide has a more rapid onset (maximum mydriasis in 15-30 minutes) of action and a shorter duration of action (pupil returns to normal in 6-12 hours in most animals) than does atropine, thereby making it more useful for funduscopic examinations. In dogs, intraocular pressure is apparently not affected by tropicamide.
Suggested Dosages/Precautions/Adverse Effects – Once or twice application to eye, prior to exam. Following cataract surgery: apply 2-3 times daily to keep pupil constantly changing in size and reduce formation of synechiae associated with prolonged pupillary dilation (atropine). Note: a current trend away from the use of mydriatics after intraocular surgery has developed in recognition of immediate postoperative pressure elevations in some animals following surgery.
Tropicamide is less effective in pain control (cycloplegia) than atropine.
Tropicamide may cause salivation, particularly in cats and may also sting when applied. Tropicamide may precipitate acute congestive glaucoma in predisposed patients.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary Approved Products: None
Human-Approved Products: Tropicamide Solution 0.5% and 1% in 2 ml & 15 ml bottles; Mydriacyl® (Alcon), Opticyl® (Optopics), Tropicacyl® (Akorn), Generic; (Rx)
Topical Anesthetics
Indications/Pharmacology – Proparacaine is a rapid acting topical anesthetic useful for a variety of ophthalmic procedures including tonometry (intraocular pressure measurement), relief of corneal pain to facilitate examination, biopsy/sample collection, and to distinguish between corneal and uveal pain. Proparacaine primarily anesthetizes the cornea; with limited penetration into conjunctiva. Anesthesia is of short duration (5-10 minutes).
Suggested Dosages/Precautions/Adverse Effects– Usual dose is 1 – 2 drops prior to examination or procedure. For prolonged procedures only requiring local anesthesia; may repeat 1 drop doses every 5-10 minutes for 5-7 doses.
Topical anesthetics should not be used to treat painful eye disease. Prolonged use may retard wound healing and cause corneal epithelial ulcers. Because the blink reflex may be suppressed, the eye should be protected from external injury during use. Repeated use may lead to rapid development of tolerance. Local allergic-type reactions have been rarely reported in humans.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products:
Proparacaine HCl Solution 0.5% in 15 ml bottles; Ophthaine® (Solvay); (Rx)
Protect from light. Refrigerate.
Human-Approved Products:
Proparacaine HCl Solution 0.5% in 2 & 15 ml bottles; Ophthetic® (Allergan), Alcaine® (Alcon), Ophthaine® (Squibb), AK-Taine® (Akorn), Generic; (Rx)
Protect from light. Some products should be refrigerated; check label.
Non-Steroidal Antiinflammatory Agents
Flurbiprofen Sodium (Ophthalmic)
Indications/Pharmacology – Flurbiprofen is a non-steroidal anti-inflammatory agent that probably acts by inhibiting the cyclo-oxygenase enzyme system, thereby reducing the biosynthesis of prostaglandins. Prostaglandins may mediate certain kinds of ocular inflammation. They may disrupt the blood-aqueous humor barrier, cause vasodilation, increase intraocular pressure and leukocytosis, and increase vascular permeability. Prostaglandins may also cause iris sphincter constriction (miosis) independent of cholinergic mechanisms. Flurbiprofen can inhibit this intraocular miosis and may also be useful in the management of uveal inflammation (usually in addition to topical steroids).
Suggested Dosages/Precautions/Adverse Effects – Prior to surgery: One drop 4 times at 20 minute intervals.
Because flurbiprofen may be as immunosuppressive as topical corticosteroids, it should not be used in patients with infected corneal ulcers. By blocking prostaglandin synthesis, arachidonic acid metabolites may be shunted into leukotriene pathways and this effect may result in a transient increase in intraocular pressure commonly noted after intraocular surgery. Postoperative pressure spikes following cataract surgery have been the subject of much study in recent years and a general trend away from the use of flurbiprofen prior to cataract surgery has resulted from these studies.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products:
Flurbiprofen Sodium 0.03% Solution in 2.5, 5 & 10 ml btls; Ocufen® (Allergan); (Rx)
Ketorolac Tromethamine (Ophthalmic)
Indications/Pharmacology – Ketorolac tromethamine is a pyrrolol-pyrrole nonsteroidal anti-inflammatory agent that inhibits prostaglandin formation. Prostaglandins mediate inflammation within the eye by disrupting the blood-aqueous barrier, inducing vasodilation and increasing intraocular pressure. Prostaglandins may also cause iris sphincter constriction (miosis) independent of cholinergic mechanisms. Ketorolac tromethamine is marketed for use before cataract extraction in human patients (to prevent miosis during surgery) and for control of post surgical inflammation, especially following cataract surgery. It is also approved for management of conjunctivitis associated with seasonal allergy in people. In veterinary medicine, ketorolac tromethamine is primarily used to control surgical or nonsurgical uveitis particularly in cases with concurrent corneal infection when topical corticosteroids are contraindicated or in diabetic patients, especially smaller patients, adversely affected by systemic uptake of topically applied corticosteroids. Nonsteroidal agents like ketorolac tromethamine can be combined with topical steroids in patients with severe uveal inflammation.
Suggested Dosages/Precautions/Adverse Effects – Prior to surgery: One drop 4 times at 20 minute intervals. One drop four times daily following cataract surgery or for treatment of uveitis or for management of allergic conjunctivitis.
The manufacturer indicates that ketorolac tromethamine does not enhance the spread of preexisting corneal fungal, viral or bacterial infections in animals models. Ketorolac tromethamine does not in and of itself induce postoperative pressure elevation other then that which frequently follows cataract extraction in people and animals.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products:
Ketorolac Tromethamine Solution 0.5% 3, 5, 10 ml; Acular® (Allergan); (Rx)
Diclofenac Sodium (Ophthalmic)
Indications/Pharmacology – Diclofenac sodium is a phenylacetic acid that inhibits cyclooxygenase, inhibiting prostaglandin synthesis. Diclofenac sodium topical solution reduces inflammation following cataract extraction in people and counteracts photophobia in humans having refractive corneal surgery. In veterinary medicine, diclofenac sodium is used for treatment of uveitis following surgery on the eye or other causes of uveitis especially when corneal infection is suspected or in diabetic patients whose insulin regulation could be altered by the systemic uptake of topical corticosteroids. Diclofenac can be combined with topical corticosteroids for better control of uveitis in animals when the condition is severe.
Suggested Dosages/Precautions/Adverse Effects – Prior to surgery: One drop 4 times at 20 minute intervals. One drop four times daily following cataract surgery or for the treatment of uveitis. Caution should be used when applying any anti-inflammatory agent on the cornea in the face of corneal stromal infection because of the positive role inflammation plays in the immune response to microbial invasion of tissue. A stinging sensation is noted in 15% of people using this medication.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products: Diclofenac Sodium 0.1% in 2.5, 5 ml; Voltaren® (Ciba Vision); (Rx)
Antiinflammatory Mast Cell Stabilizers
Lodoxamine Tromethamine (Ophthalmic)
Indications/Pharmacology – Lodoxamine tromethamine is a mast cell stabilizer that inhibits Type I hypersensitivity responses by preventing antigen mediated histamine release. Lodoxamine stabilizes mast cells by blocking calcium influx into the cell upon antigen recognition, thereby blocking histamine release. Lodoxamine has no intrinsic vasoconstrictor, antihistaminic, cyclooxygenase inhibition or other anti-inflammatory properties. Lodoxamine is used in people for management of conjunctivitis associated with seasonal allergy and other histamine mediated disorders. In veterinary medicine, lodoxamine tromethamine has been used in horses and small animal patients with presumed allergic conjunctivitis.
Suggested Dosages/Precautions/Adverse Effects – Prior to surgery: One drop 2-4 times daily. A stinging sensation is noted in a low percentage of people using this medication.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products: Lodoxamine Tromethamine 0.1% 10ml; Alomide® (Alcon); (Rx)
Indications/Pharmacology – Cromolyn sodium is a mast cell stabilizing agent that blocks release of histamine and slow-reacting substance of anaphylaxis from mast cells following antigen recognition. Similar to lodoxamine tromethamine, cromolyn sodium has no intrinsic vasoconstrictor, antihistaminic, cyclooxygenase inhibition or other anti-inflammatory properties. Mast cell stabilizing agents are most useful in animal patients suffering from allergic conjunctivitis.
Suggested Dosages/Precautions/Adverse Effects – Prior to surgery: One drop 2-6 times daily. A stinging sensation is noted in a low percentage of people using this medication.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products: Cromolyn Sodium 4% in 2.5, 10ml; Crolom® (Bausch & Lomb); (Rx)
Corticosteroids, Topical (Ophthalmic)
(see also Antibiotic & Corticosteroid Combinations)
Indications/Dosages/Precautions – Topical corticosteroids are used to treat diseases of the eye involving the conjunctiva, sclera, cornea, and anterior chamber. Penetration of topically applied corticosteroids into the eyelids is poor as is penetration to the posterior segment of the eye. Corticosteroid-responsive conditions affecting these areas are usually managed with systemically administered agents (with or without adjunctive topically applied medications).
Conjunctivitis in animals is often treated symptomatically, particularly during the first occurrence of the condition for any particular patient. Antibiotic agents with hydrocortisone or dexamethasone, or antibiotic agents alone initially, are used for conjunctivitis in the dog and the horse. Allergic and eosinophilic conjunctivitis are rare diagnoses in the cat. Topically applied corticosteroids should not be used to treat conjunctivitis in cats. Herpes virus is the most common feline conjunctival pathogen and topically applied steroids can induce prolonged disease, steroid dependency and corneal complications including ulcerative keratitis and/or corneal sequestrum formation.
Inflammatory conditions of the canine sclera and episclera include episcleritis, scleritis, nodular granulomatous episclerokeratitis, Collie granuloma and others. Potency and penetration of corticosteroid agents is important in the management of these conditions. Dexamethasone sodium phosphate ointment is often employed and the relatively reduced penetration of the fibrous ocular tunics of this medication compared with that of 1% prednisolone acetate ophthalmic suspension is made up for by increased contact time of the ointment form of this drug and by the increased potency of dexamethasone (30X cortisone) relative to prednisolone (4-5X cortisone). Dexamethasone products alone (without antibiotics) are becoming increasingly scarce in the marketplace and because of this, dexamethasone is often used in combination with an antibiotic for availability reasons only. Four times daily treatment is often the initial frequency with tapering paralleled to clinical response. Topical treatment is often used following subconjunctival injection of corticosteroid agents into or adjacent to the lesion (if focal). Systemic steroid treatment is usually not necessary.
Nonulcerative inflammatory conditions of the cornea of animals include chronic superficial keratitis (pannus) of the German Shepherd and other breeds, eosinophilic keratitis of the cat and certain, often poorly understood, keratopathies of the equine, including Onchocerca related keratitis. German Shepherd pannus may be better managed using cyclosporine ophthalmic solution or ointment with or without concurrent topical steroids initially followed by long term management with cyclosporine ophthalmic alone (see cyclosporine ophthalmic). Eosinophilic keratitis is often treated with subconjunctival corticosteroids in addition to topical 0.1% dexamethasone ophthalmic ointment or solution or 1% prednisolone acetate ophthalmic suspension 4 times daily, tapering the dosage frequency based on clinical response. Recent research reveals that eosinophilic keratitis may be an unusual immune response to latent feline herpes virus in the corneal stroma, calling into question the value of topical steroids in the management of a disease with an infectious etiology. Equine keratopathies are treated with 0.1% dexamethasone ointment 4 times daily with tapering of the treatment frequency based on the clinical response.
Corticosteroids are also used to manage anterior uveal inflammatory disease of companion animals. In small animals, 1% prednisolone acetate ophthalmic suspension is generally used for this purpose because of superior penetration into the anterior segment of the eye in comparison with dexamethasone products. The frequency of treatment depends on the severity of the condition. Severe anterior uveitis can be treated with subconjunctival corticosteroids given in combination with hourly topical corticosteroids with reevaluation performed again 24 hours after beginning treatment. Moderate to mild uveitis and that found following surgery of the anterior segment is often treated initially at the QID level with tapering based on clinical response. Anterior uveitis in animals can often be associated with an underlying systemic infectious or neoplastic condition in animals. Clinicians are advised to evaluate the patient for generalized infectious or neoplastic conditions prior to or concurrent with a course of corticosteroid antiinflammatory therapy, particularly if the condition dictates systemic treatment with these agents in combination with subconjunctival and topical treatment. Uveitis in the equine species is often treated with either 1% prednisolone acetate ophthalmic suspension or with 0.1% dexamethasone ointment. Many clinicians prefer to use the ointment because of increased contact time and potency and the logistics of frequent treatment of this species. 1% prednisolone acetate can be passed through a subpalpebral lavage catheter very frequently to treat equine patients with anterior uveitis when necessary.
Pred Forte®, Econopred Plus® or generic 1% prednisolone acetate ophthalmic suspension are the prednisolone products most used by veterinary ophthalmologists. There are few indications for Econopred® or Pred Mild® in veterinary ophthalmology.
Inflammatory condition of the posterior segment require systemic treatment because of poor penetration of topically applied agents.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products:
Prednisolone Acetate Drops: 0.12% Suspension Pred Mild® (Allergan); 0.125% Suspension Econopred® (Alcon); 1% Suspension; Econopred Plus® (Alcon); Pred Forte® (Allerga_n; Generic; (Rx)
Prednisolone Sodium Phosphate Drops: 0.125% Solution (various manufacturers); 1% Solution (various); (Rx)
Combination of Prednisolone (0.25%) and Atropine (1%) Drops: Mydrapred® (Alcon) in 5 ml bottles; (Rx)
Also available: Fluorometholone or Medrysone drops.
Other routes of administration: Systemically administered corticosteroids (usually orally) may be indicated for non-infectious inflammatory ocular conditions and following intraocular surgery. Subconjunctival steroids are useful in anterior segment inflammatory disease and following cataract surgery and intraocular glaucoma surgery. Subconjunctival steroids may be absorbed systemically and should be used with caution in patients with endocrinopathies (e.g., diabetes mellitus) or infectious diseases.
Antibiotics, Single and Combination Agents
Indications/Pharmacology/General Use Considerations – Topical antibiotic agents are commonly used to treat conjunctivitis and ulcerative keratitis complicated by bacterial infection of the corneal stroma. These agents are also used to prevent infection following surgery of the eyelids, conjunctiva, cornea, and the anterior segment. Conjunctivitis in animals is a common clinical entity. Because in most instances the condition does not threaten vision, it is often treated symptomatically with antibiotic agents or antibiotic agents in combination with topical steroids (see antibiotic/corticosteroid combination agents). Conjunctivitis is an exclusion diagnosis in animals, ruling out other causes for ocular discomfort and discharge, including anterior uveitis, glaucoma and inflammatory disease of the sclera, episclera and cornea. Triple antibiotic products (neomycin, bacitracin and polymyxin B) are often employed for this purpose, with or without hydrocortisone, because these drugs are not used systemically and because the combination of antibiotics is broad spectrum. Triple antibiotic or triple antibiotic HC is often used in dogs 4 times daily for 1 to 2 weeks for conjunctivitis. Chronic or recurrent cases of conjunctivitis would indicate further diagnostic evaluation to determine an underlying cause. Tetracycline ophthalmic ointment is often used QID in cats for nonspecific or undiagnosed conjunctivitis. The rationale for this treatment is the efficacy of tetracycline for Chlamydia spp. and Mycoplasma spp., two infectious agents reported to cause conjunctivitis in the cat. Antibiotic agents with corticosteroids should not be used for the treatment of conjunctivitis in the cat. The majority of cases are related to primary or recurring infection with feline herpes virus and recent evidence indicates that topical or systemic steroid therapy can potentially prolong the duration of the viral infection and result in corneal complications in cases which otherwise may have remained a conjunctival infection. Triple antibiotic with or without hydrocortisone is often used to treat conjunctivitis in the equine species. Sensitivity to triple antibiotic in dogs and cats has been noted and is reportedly the result of neomycin allergy, as is noted in people.
Antibiotic therapy for corneal disease varies from prophylactic therapy to prevent infection to treatment of established corneal infections. Following an acute superficial injury to the cornea in the dog, cat or horse, treatment with triple antibiotic ointment or drops 4 times daily is usually sufficient to prevent bacterial infection of the corneal stroma. Reevaluation of the patient 24-48 hours after the injury is indicated. Progressive edema, pain, and white opacification of the cornea (cellular infiltrate) would suggest that the antibiotic protocol (agent and frequency) has failed to prevent bacterial infection.
Established bacterial infection of the corneal stroma is managed medically or surgically depending on the depth of infection. Ulcerative keratitis with bacterial infection causing deterioration of 50-75% of the stromal thickness is usually treated with conjunctival or corneal grafting in addition to antibiotic therapy. This is done to introduce immune system components and a blood supply to the cornea (conjunctival graft) in addition to replacing lost stromal tissue. Conjunctival grafting will usually stabilize stromal deterioration secondary to bacterial infection but carries the disadvantage of permanent opacification of the cornea in the site of previous ulcerative keratitis (unless other surgeries are performed). Aggressive medical management with topical antibiotic agents is often successful in controlling corneal infection which involves 75% or less of the depth of the cornea. The slit lamp biomicroscope is used by ophthalmologists at referral centers and specialty clinics to determine the depth of corneal involvement.
Clinical signs of bacterial infection of the corneal stroma includes increasing pain, progressive corneal opacity, hypopyon, and the development of a progressively expanding indentation or crater in the surface of the cornea. Cytology is indicated in the management of such patients. Gram staining is usually not necessary. Cocci noted with Dif-Quick® or related stains are considered to be gram positive cocci. Those cocci forming chains are considered to be Streptococcus organisms. Those cocci of variable size and shape and forming grape clusters are considered to be Staphylococcal organisms. Rods are considered to be gram negative organisms and Pseudomonas spp. is suspected. A degree of suspicion for fungal keratitis should be maintained while evaluating cytologic material collected from the cornea of the horse. Fungal hyphae stain dark blue with Dif-Quick® type stains. Culture and sensitivity tests are informative but the information is available at a time when the efficacy of the antibiotic therapy chosen has already been established. In 24-48 hours the case will show signs of improvement, indicating efficacy of the therapeutic protocol or the condition will have advanced and surgery will be under consideration. Sensitivities are relatively meaningless because aggressive medical treatment can result in corneal drug concentrations several times the MIC and sometimes beyond that considered toxic on a systemic basis. The use of eyedrops rather than ointments is recommended for aggressive medical management protocols.
Cytologic evaluation of material from the cornea will dictate antibiotic selection for aggressive medical management of corneal ulcers. Cocci are often treated with frequent application of triple antibiotic drops. Gentamicin has limited spectrum for Streptococci spp. and would not be a first choice agent when cocci forming chains are noted on cytologic evaluation of material from an infected corneal ulcer. Gentamicin has efficacy for some Staphylococcal spp. Chloramphenicol is also an antibiotic available for treatment of gram positive infections of the cornea. Gram negative infections of the cornea are often treated with gentamicin, tobramycin or the quinolones. Several studies indicate that a bacterial infection of the corneal stroma that responds to tobramycin is usually as responsive to gentamicin applied frequently making the newer aminoglycoside and quinolone antibiotics rarely necessary. These agents are reserved for very specific instances of stromal infection with highly resistant organisms and should not be considered for prophylactic treatment. Applied very frequently, bactericidal concentrations of either triple antibiotic or gentamicin ophthalmic solutions can be achieved in the corneal stroma making these two agents effective for the vast majority of corneal infections in companion animals. Relative penetration of antibiotic agents into the cornea is irrelevant during the treatment of ulcerative keratitis. All agents are water soluble (eye drops) and would penetrate the corneal stroma similarly. Penetration of various antibiotic agents into the cornea is a consideration when the corneal epithelium is intact as is often noted with the development of stromal abscessation in equines.
Aggressive medical management protocols involve hourly or q30 minute application of topical antibiotics. Sometimes two agents are used with synergistic properties (for example an aminoglycoside and a cephalosporin). One agent is applied on the hour and the other on the half hour. Single agents are usually applied hourly. The case is reevaluated 18-24 hours after initiation of the treatment regimen. Increased patient comfort, reduced corneal edema and no increase in the depth or width of the corneal ulcer are signs of efficacy of the selected treatment plan. In some cases at 24 hours and most cases by 30 hours, the peripheral “rim” of the corneal ulcer will fail to take on fluorescein stain, indicating early epithelialization of the corneal ulcer. It is the author’s (DKO) impression that epithelialization of the ulcer will not occur until the stromal infection has been arrested. Cytologic evaluation of material collected from the cornea can be repeated to evaluate efficacy of the drug(s) selected. Clinical improvement signals the clinician to begin reducing treatment frequency slowly over the next two days, working towards the QID level. Long term aggressive medical management is not recommended because several agents, especially the aminoglycosides, are epitheliotoxic and prolonged once per hour treatment likely would delay healing rather than improve the case.
Aggressive medical management usually requires hospitalization in an intensive care unit for careful treatment and monitoring of the case. The advantage of aggressive medical management is reduced opacity in the cornea in comparison with conjunctival grafting. This is associated with an improved visual result, particularly if the injury is central. Medical management is usually less expensive than surgical treatment. General anesthesia is not necessary for aggressive medical management. Although aggressive medical management may result in halting further bacterial deterioration of stromal tissue in very deep corneal ulcers, reepithelialization of Descemet’s membrane or a thin layer of corneal stroma interposed between Descemet’s membrane and the corneal epithelium leaves the cornea dangerously thin. Minor trauma to the eye could result in rupture of the cornea across this area and loss of the anterior chamber.
Post surgical prophylactic medical treatment usually involves triple antibiotic agents because of their broad spectrum and because they are not agents used systemically. Four times daily treatment is recommended. Ointments are commonly used after surgery of the eyelids, conjunctiva or cornea. Eyedrops are usually used following surgery of the cornea or anterior segment. Bacterial infection of the anterior chamber alone is uncommon. Bacterial endophthalmitis carries a poor prognosis for saving vision or the globe in animals and is usually managed surgically in people. Gentamicin is sometimes used for prophylactic therapy of the equine species because of a greater number of gram negative organisms in the environment of this species, although the aminoglycosides would not be a first choice agent for prophylactic medical treatment of small animals. Tobramycin and the quinolones would not be considered for prophylactic treatment following surgery performed under sterile conditions.
Indications/Pharmacology – A broad spectrum antibiotic, chloramphenicol has the ability to cross the corneal barrier and enter the anterior chamber. However, there are very few infections that occur in the anterior chamber and if bacteria are actually present there, the blood ocular barrier is lost and systemically administered antibiotics can achieve therapeutic levels.
Because of the potential toxicity associated with chloramphenicol to humans, chloramphenicol’s use in veterinary ophthalmology is becoming less widespread. It may be useful, however, in treating cats with suspected Mycoplasma or chlamydia conjunctivitis.
Suggested Dosages/Precautions/Adverse Effects – For prophylaxis following surgery or for cats with Mycoplasma or chlamydial conjunctivitis: One drop (or 1/4 inch strip if using ointment) four times daily. For established corneal infection: Application may be very frequent (up to hourly).
Chloramphenicol exposure in humans has resulted in fatal aplastic anemia. For this reason, this drug should be used with caution in veterinary patients and some ophthalmologists avoid its use entirely. Clients should be cautioned to use appropriate safeguards when applying the drug and avoiding contact with drops or solutions after application.
Labels state to not use longer than 7 days in cats, but tid application of ointment for 21 days to cats did not cause toxicity. Must not be used in any food producing animal.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products:
Chloramphenicol 1% Ophthalmic Ointment in 3.5 gm; Bemacol®-(Pfizer); Chlorbiotic®-(Schering); Chloricol® (Evsco); Generic; (Rx)
Chloramphenicol 0.5% Ophthalmic Drops in 7.5 ml btls tubes; Chlorasol®-(Evsco); (Rx). Refrigerate until dispensed.
Approved for use in dogs and cats.
Human-Approved Products:
Chloramphenicol 1% Ophthalmic Ointment in 3.5 gm tubes; Chloromycetin® (Parke Davis); Chloroptic® (Allergan); Generic (Rx)
Chloramphenicol 0.5% Ophthalmic Drops in 7.5 ml btls tubes; Chloroptic® (Allergan); Generic; (Rx). Refrigerate until dispensed.
Norfloxacin (Ophthalmic)
Ofloxacin (Ophthalmic)
Indications/Pharmacology – These fluroquinolone ophthalmic antibiotics are primarily useful for established gram negative corneal infections. They are not recommended for prophylactic use prior to or after surgery. See the main enrofloxacin/ciprofloxacin monograph for additional pharmacologic information.
Precautions/Adverse Effects – Ciprofloxacin may cause crusting or crystalline precipitates in the superficial portion of corneal defects. Other potential adverse effects with quinolones include: conjunctival hyperemia, bad taste in mouth, itching foreign body sensation, photophobia, lid edema, tearing keratitis and nausea. Allergic reactions have been reported with quinolone eye preps.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products:
Ciprofloxacin 3 mg/ml drops in 2.5 & 5 ml btls; Ciloxan ® (Alcon); Rx
Norfloxacin 3 mg/ml drops in 5 ml btls; Chibroxin ® (Merck); Rx
Ofloxacin 3 mg/ml drops in 5 ml btls; Ocuflox ® (Allergan); Rx
Tobramycin (Ophthalmic)
Indications/Pharmacology – The aminoglycosides are excellent drugs for gram negative or staphylococcal corneal infections. With frequent application, clinicians can establish corneal drug levels far in excess of MIC for most organisms without exceeding toxic systemic levels. Therefore, MIC reports may not be meaningful. Because of the high levels attainable, gentamicin usually exhibits similar efficacy to tobramycin, except in certain resistant gram-negative infections (e.g., Pseudomonas aeruginosa).
For serious gram negative or staphylococcal corneal ulcer infections, some ophthalmologists use cefazolin eye drops (compounded preparation) in combination with gentamicin or tobramycin. Synergism may result.
Precautions/Adverse Effects – Hypersensitivity, and localized ocular toxicity (lid itching, swelling and conjunctival erythema) have been reported rarely. Mydriasis and conjunctival paresthesias may also occur.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products:
Gentamicin Ophthalmic Ointment 3 mg/g in 3.5 gm tubes; Gentocin ® (Schering); (Rx). Approved for use in dogs and cats.
Gentamicin Ophthalmic Drops 3 mg/ml in 5 ml btls Gentocin® (Schering); (Rx). Approved for use in dogs and cats.
Human-Approved Products:
Gentamicin Ophthalmic Ointment 3 mg/g in 3.5 gm tubes; Garamycin® (Schering); Genoptic® (Allergan); various; (Rx)
Gentamicin Ophthalmic Drops 3 mg/ml in 5 ml btls Garamycin® (Schering); Genoptic® (Allergan); various; (Rx)
Tobramycin Ophthalmic Ointment 3 mg/g in 3.5 gm tubes; Tobrex® (Alcon); (Rx)
Tobramycin Ophthalmic Drops 3 mg/ml in 5 ml btls Tobrex® (Alcon); (Rx)
Indications/Pharmacology – The tetracyclines are most useful in cats for the treatment Chlamydial and Mycoplasma conjunctivitis as well as nonspecific or symptomatic therapy for undiagnosed (causative organism not determined) conjunctivitis in cats. While its use in dogs and horses is questionable, it may be useful in goats for Chlamydial/Mycoplasma keratoconjunctivitis.
Tetracycline is often used to “back into” the diagnosis of herpes virus conjunctivitis in cats. Since the majority of conjunctivitis cases in cats are caused by herpes virus (approx. 90%) and the bulk of the remainder are caused either by Chlamydia or Mycoplasma, if the cat fails to respond to tetracycline, the cause is most likely due to herpes virus.
Suggested Dosages/Precautions/Adverse Effects – For Chlamydial/Mycoplasma keratoconjunctivitis: Apply 4 times daily. Dramatic improvement should be noted in 3-4 days, but treatment should continue for 3-4 weeks for Chlamydia to break the reproductive cycle of this organism.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products:
Tetracycline HCl Ointment 10 mg/g in 3.75 g tubes Achromycin ® (Storz/Lederle); (Rx)
Tetracycline HCl Suspension 10 mg/ml in 4 ml btls Achromycin® (Storz/Lederle); (Rx)
Other available ophthalmic antibiotics: Chlortetracycline: Aureomycin® (Storz Lederle); Bacitracin (alone); Erythromycin Ointment; Polymyxin B powder for solution; Sodium Sulfacetamide.
Antibiotic Combinations (Ophthalmic)
Indications/Pharmacology – These combination products exhibit a broad-spectrum of activity and are considered the first choice for symptomatic treatment of conjunctivitis in dogs and for prophylactic treatment of small animals prior to or after eye surgery. These agents are also used prophylactically for corneal injuries/wounds.
Suggested Dosages/Precautions/Adverse Effects – Usually applied 4 times daily to prevent infection and up to every 30 minutes in established corneal infections. See individual product label information and the information noted previously.
Neomycin has been reported to cause allergic reactions in dogs and cats, particularly after prolonged usage.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products:
Ointments: Bacitracin zinc 400 units/Neomycin 3.5 mg/Polymyxin B Sulfate 10,000 Units per gram in 3.5 gm tubes Mycitracin® (Upjohn) (Note: contains 500 mg bacitracin/gm); Neobacimyx® (Schering); Trioptic-P® (Pfizer); Vetropolycin® (Pitman-Moore); Generic. All are Rx and approved for dogs and cats.
Oxytetracycline HCl 5 mg/Polymyxin B Sulfate 10,000 U/gm in 3.5 gm tubes Terramycin® Ophthalmic Ointment (Pfizer); OTC. Approved for use in dogs, cats, sheep, cattle, and horses.
Drops:
Neomycin 3.5 mg/Polymyxin B Sulfate 10,000 Units per ml: Optiprime®-(Syntex); Rx. Approved for use in dogs.
Human-Approved Products:
There are a wide variety of human-labeled ophthalmic combination products available. Most are a combination of bacitracin/neomycin/polymyxin B. However, there are variations of this theme (e.g., gramicidin in place of bacitracin in topical solutions-Neosporin® Ophthalmic Solution). All these products require a prescription.
Antibiotic & Corticosteroid Combinations (Ophthalmic)
Indications/Pharmacology – There are three basic categories of these products that are routinely used in veterinary medicine; antibiotic combinations with hydrocortisone, antibiotic combinations with dexamethasone, and individual antibiotics (e.g., gentamicin or chloramphenicol) with a steroid.
Antibiotic combinations with hydrocortisone (ointment or solution) are used in dogs and horses for conjunctivitis as nonspecific therapy after ruling out other causes for red painful eyes, including glaucoma and anterior uveitis. They generally are applied 4 times daily and then on a tapering schedule based on the response to therapy. The hydrocortisone is relatively weak as an antiinflammatory agent and is not effective for intraocular inflammatory disease such as anterior uveitis. The relative penetration and potency of hydrocortisone in these preparations makes them relatively ineffective for immune mediated extraocular disease including scleritis, episcleritis and or nodular granulomatous episclerokeratitis. Anterior uveitis is statistically more common in horses than simple conjunctivitis and the steroid in these agents would not be helpful in improving the clinical signs of immune mediated uveitis.
Antibiotic combinations with dexamethasone are valuable for use in cases of more severe canine or equine conjunctivitis, nonulcerative keratitis and for immune-mediated scleral or corneal conditions such as chronic superficial keratitis (German Shepherd pannus), feline eosinophilic keratitis, scleritis, episcleritis and nodular granulomatous episclerokeratitis. For these conditions the antibiotic agent is not necessary but dexamethasone-only products are not always available. These medications are also used in the equine species with equine uveitis because the ointment forms persist on the cornea longer than drops and because they are less expensive than prednisolone acetate ophthalmic suspensions.
Single agent antibiotic (gentamicin) and potent steroid (betamethasone) combination products (e.g., Gentocin Durafilm®) are commonly used in veterinary medicine. However, there are few instances in veterinary ophthalmology in which a very potent corticosteroid agent and an aminoglycoside antibiotic are necessary in combination. Simple conjunctivitis in dogs and horses is adequately treated with antibiotic combinations with hydrocortisone. Avoid use of this agent in cats with conjunctivitis for the reasons noted below.
Suggested Dosages/Precautions/Adverse Effects – See individual product label information and the information noted above.
Avoid use of antibiotic/steroid combination agents in cats with conjunctivitis as the most common cause of conjunctivitis in the cat is primary or recurring infection with exposure to, or reactivation of, latent feline herpes virus. Recent research indicates that topical steroids increase the length of the typical course of feline herpes virus related conjunctivitis and/or keratitis and can induce corneal involvement in cases which might otherwise have remained confined to conjunctiva. Corneal sequestration has been noted to occur in cats with herpes virus conjunctivitis after treatment with topical steroids. Recommended treatment for feline herpes virus conjunctivitis is tetracycline ointment QID during active disease, as this drug is effective against Mycoplasma and chlamydia (other causes of infectious conjunctivitis in the cat).
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products:
Triple Antibiotic Ointments with Hydrocortisone:
Bacitracin zinc 400 units/Neomycin 3.5 mg/Polymyxin B Sulfate 10,000 Units & Hydrocortisone acetate 1% per gram in 3.5 gm tubes Neobacimyx H® (Schering); Trioptic-S® (Pfizer); Vetropolycin HC®– (Pitman-Moore); Generic. All are Rx and approved for dogs and cats.
Other Antibiotic/Steroid Ointments:
Neomycin Sulfate 5 mg & Prednisolone 2 mg (0.2%) per gram in 3.5 gram tubes (Optisone®-Evsco); (Rx). Approved for use in dogs and cats.
Neomycin Sulfate 5 mg & Isoflupredone acetate 1 mg (0.1%) per gram in 3.5 & 5 gram tubes Neo-Predef® Sterile Ointment® (Upjohn); (Rx). Approved for use in horses, cattle, dogs and cats.
Chloramphenicol 1% and Prednisolone acetate 2.5 mg (0.25%) in 3.5 gm tubes; Chlorasone® (Evsco) (Rx). Approved for use dogs and cats.
Drops:Gentamicin Ophthalmic Drops 3 mg/ml & Betamethasone acetate 1 m/ml in 5 ml btls Gentocin Durafilm® (Schering); (Rx). Approved for use in dogs.
Human-Approved Products:
There are a wide variety of human-labeled ophthalmic antibiotic/steroid combination products available. Some of the more commonly used combinations include:
Ointments:
Bacitracin/Neomycin/Polymyxin B and Hydrocortisone Cortisporin® (BW)
Neomycin/Polymyxin B & Dexamethasone Maxitrol® (Alcon); (Rx)
Neomycin and Dexamethasone NeoDecadron® (Merck); (Rx)
Drops:
Neomycin/Polymyxin B and Hydrocortisone Cortisporin® (BW, etc.); (Rx)
Neomycin/Polymyxin B & Dexamethasone Maxitrol ® (Alcon); (Rx)
Neomycin and Dexamethasone NeoDecadron® (Merck); (Rx)
Antifungals (Ophthalmic)
Fungal keratitis is a serious corneal disease, most commonly reported in the horse. The species selectivity of this disease is related to the environment of this animal, which is often contaminated with fungal elements. An increased incidence of fungal keratitis in people was directly related to the development of multiple topical steroid agents for treatment of eye diseases. In the horse, many cases of fungal keratitis are noted in association with prior treatment of conjunctival and/or corneal diseases with topical steroid agents. Aspergillus is the most common cause of fungal keratitis in the horse, although there is a great deal of variation in fungal isolates from the cornea depending upon geographical location. Studies in people and anecdotal reports from veterinarians suggest that fungal keratitises due to Fusarium organisms are more resistant to therapy than are those caused by aspergillus. Most studies in the equine suggest that about 50% of cases of fungal keratitis in the horse result in perforation of the corneal and enucleation of the eye. Medical and surgical therapy (keratectomy, corneal debridement, and conjunctival grafting) are used to treat such cases with the goals of therapy including arresting infection, mechanical removal of organisms from the cornea, and support of the cornea. All antifungal agents available for use in the equine suffer from poor penetration into the corneal stroma. Conjunctival grafting may further hinder drug penetration as a trade off to improving vascular availability to the cornea and mechanical support. Pathologic specimens from horses with fungal keratitis indicate that fungal organisms, unlike bacterial organisms, have a propensity to multiply deep in the stroma, directly adjacent to Descemet’s membrane, making corneal penetration an important issue. Because the prognosis for return of vision and saving the globe in cases of fungal keratitis cases is guarded and because treatment is labor intensive, referral to teaching or other hospitals for 24 hour care and observation is recommended.
Indications/Pharmacology – Natamycin is a semisynthetic polyene antibiotic. Natamycin is poorly water soluble and will not penetrate the intact corneal epithelium. Natamycin is the only antifungal agent approved for use on the eye and the only commercially available eye drug for treatment of fungal keratitis.
Suggested Dosages/Precautions/Adverse Effects – The product comes as a thick white suspension which complicates the use of subpalpebral lavage apparatus for frequent treatment of the cornea of the horse. The drug tends to plug up the tubing systems used for medication. It will cause dramatic swelling and pain in the upper eyelid if it leaks out of the tubing into the subcutaneous tissues of the eyelid. Corneal penetration is poor and the medication is very expensive. Fungal keratitis cases are treated aggressively with hourly or bi-hourly treatment the first 1 to 3 days and gradual reduction in treatment frequency with signs of clinical improvement. Cytology and repeated cultures of the cornea are used to indicate treatment effectiveness. Worsening of the corneal edema and cellular infiltration can be a sign of treatment response. This is thought to be due to antigenic release associated with killing of fungal organisms (like the pulmonary response noted in dogs with institution of antifungal therapy for blastomycosis, etc.). Four to six weeks of treatment is not uncommon for fungal keratitis cases.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products:
Natamycin Ophthalmic Suspension 5% in 15 ml btls Natacyn ® (Alcon); (Rx)
Indications/Pharmacology – Miconazole is a broad spectrum imidazole antifungal agent with some antibacterial activity. Miconazole will penetrate the intact corneal epithelium. Topical miconazole therapy has been a favorite first choice agent for treatment of fungal keratitis in the horse by veterinary ophthalmologists for several years. Miconazole may be delivered by subconjunctival route, but with some local irritation, and topical use is the most commonly employed treatment method.
Suggested Dosages/Precautions/Adverse Effects – Miconazole is formulated at 10 mg/ml for IV use in humans. It can be directly taken from the glass ampule for IV use and applied to the cornea of horses. It is a clear solution readily delivered through subpalpebral lavage apparatus systems. The medication is significantly less expensive compared with natamycin and its corneal penetration is more favorable, although still less than optimal. Treatment is generally delivered hourly or bi-hourly during the first several days of treatment. Once clinical improvement is noted and cytology specimens and repeated cultures indicate eradication of fungal organisms, the treatment frequency is gradually reduced. Most fungal keratitis cases are treated 4 to 6 weeks.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products:
Miconazole Injection 10 mg/ml in 20 ml glass ampules Monistat-i.v.® (Janssen); Rx
Silver Sulfadiazine (Ophthalmic)
Indications/Pharmacology – Silver Sulfadiazine Cream is a broad spectrum agent which covers bacteria (gram positive and negative) and fungal agents. It has been used extensively in people suffering from skin burns. It is nontoxic to the skin, conjunctiva and cornea and has been used in the last several years for cases of fungal keratitis. Particularly good results have been noted in cases of superficial keratitis prior to development of advanced disease. Clinical response is better when used early in the course of the disease. Treatment with silver sulfadiazine is considered non-conventional in people. It is gaining in popularity in the treatment of equine fungal keratitis by veterinary ophthalmologists. For medico-legal reasons, in very expensive horses in which litigation may be an issue, treatment with more conventional therapy (Natamycin) may be indicated first, or consideration can be given to signed consent regarding treatment with Silver Sulfadiazine. The initial response to this drug has been promising, however.
Suggested Dosages/Precautions/Adverse Effects – The commercially available product is a cream, but can be delivered into the conjunctival sac using a tuberculin syringe, without the needle. A typical treatment dose is 0.2 ml drawn into a syringe. It will not pass through standard sized subpalpebral lavage catheters, although it may be administered through large medication administration systems using red rubber feeding tubes passed through the lid, with variable results getting the medication to pass through the tube. It is probably best applied manually. The cream sticks well to the cornea which probably improves effectiveness, similar to natamycin, as compared to miconazole. Treatment regimes are similar to the other antifungal agents with very frequent applications necessary during the early phases of the treatment and reduction in therapy based upon clinical response. Daily debridement of the necrotic corneal stroma and epithelium will improve penetration of the drug and the clinical response.
The medication is inexpensive and is available from any pharmacy, but it is not labeled for use in eyes. The label (package insert) specifically states “not to be used in eyes” so liability for use in eyes rests solely with the prescribing veterinarian and some pharmacists may be unwilling to dispense this medication for ophthalmic use.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products:
Silver Sulfadiazine Topical (not an ophthalmic product) 10 mg per gram in a water miscible cream base. Available in 20, 50, 400, and 1000 g containers; Silvadene®-(Marion); Flint SSD® (Flint); Rx
Antivirals (Ophthalmic)
Antiviral drugs are used most commonly in clinical practice for the treatment of feline ocular herpes virus infections. Simple acute conjunctivitis is best managed with symptomatic antibiotic therapy alone (i.e., tetracycline treatment). The development of concurrent corneal disease, however, indicates that consideration should be given to the use of antiviral drugs. Persistent cases of conjunctivitis in the cat due to feline herpes virus infection may also benefit from treatment with topical antiviral drugs.
Trifluridine (Trifluorothymidine)
Indications/Pharmacology – Trifluridine (trifluorothymidine; Viroptic®) is a pyrimidine nucleoside analog. It is structurally related to 2-deoxythymidine, the natural precursor of DNA synthesis. Trifluridine is poorly absorbed by the cornea and is virostatic. Viroptic® interrupts viral replication by substituting in “nonsense” pyrimidine analogues. For this reason, a competent surface immunity is necessary to resolve ocular disease, with or without antiviral therapy. A recent in vitro study in which several strains of feline herpes virus were collected from the United States and were used to infect kidney epithelial cells showed that trifluridine was more effective at lower concentrations compared with several other agents. For this reason, trifluridine is often the first choice drug employed in the treatment of feline herpes virus ocular disease. Antiviral agents have also been used in the treatment of superficial punctate keratitis in the horse, thought to be associated with equine herpes virus-2 (EHV-2) infection of the cornea.
Suggested Dosages/Precautions/Adverse Effects – Trifluridine must be applied very frequently. The author (DKO) recommends treatment every 2 hours (waking hours) during the first 2 days of therapy to establish effective corneal drug levels. After this time, treatment 4-6 times daily is indicated. Because trifluridine is virostatic and not viricidal, treatment 1 week beyond the resolution of clinical signs is recommended, to prevent a rebound effect associated with poor surface immunity in combination with residual active viral agents.
Anecdotally, improvement with antiviral agents is noted in about 50% of cats in which the treatment is employed. In some cats the ocular disease persists despite treatment with antiviral agents. It is not certain if these are truly cases of feline herpes virus infection or other disease as the confirmation of feline herpes virus infection is exceedingly difficult in practice, (except in the acute disease with respiratory and ocular involvement, because of the logistics of viral isolation tests for doctors in clinical practice (usually only available at major institutions or referral centers) and because of the high degree of false negatives with herpes virus FA tests and with available polymerase chain reaction (DNA amplification) technology). Chronic conjunctivitis in the cat seems to be the most resistant to treatment with antiviral agents.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products:
Trifluridine Ophthalmic Solution 1% in 7.5 ml btls Viroptic® (B-W); (Rx)
Agents for Keratoconjunctivitis Sicca
Keratoconjunctivitis sicca (KCS) is a common ocular disorder in dogs. Recent research efforts indicate that KCS in dogs is an immune mediated disease. It is similar to Sjogren’s Syndrome in humans except we do not recognize a connective tissue disorder in the dog compared to this disease in people (man-dry eye, dry mouth, and connective tissue disorder like rheumatoid arthritis; dogs just dry eye). Immune mediated lacrimal adenitis can result in complete destruction of tear producing glands in dogs. Glandular fibrosis produces absolute sicca and these cases may be better managed with a parotid duct transposition surgery because there may be little remaining gland tissue to treat.
Indications/Pharmacology – Cyclosporine is a polypeptide agent first isolated from a fungus. The agent interferes with interleukin synthesis by T lymphocytes and in so doing has been employed extensively in people following major organ transplantation to prevent immune rejection. Cyclosporine is extremely hydrophobic and was originally compounded by pharmacists in virgin olive oil or purified corn oil for the topical application to dogs with keratoconjunctivitis sicca. Topical cyclosporine is now commercially available as a 0.2% ointment (Optimmune®-Schering). The mechanism of action of cyclosporine in the treatment of keratoconjunctivitis sicca is still not fully understood, although it has been employed in the treatment of KCS in dogs for several years. It stimulates increased tear production in normal dogs and for this reason it is thought to have a direct stimulatory effect on the tear gland. It may do this acting as a prolactin analog, fitting onto lacrimal prolactin receptors. Its interleukin blocking effects likely are the major mechanism of action. Halting local inflammatory mediator production appears to arrest self perpetuating lacrimal adenitis resulting in resumption of normal or improved tear production after several weeks of therapy. Cyclosporine in the cornea, appears to have the ability to lessen granulation and pigment development. This property appears to be unrelated to its tear producing ability.
The reported success rate of alleviating the signs of KCS in dogs with treatment with cyclosporine is 75-85%. Some studies indicate that the higher the Schirmer value prior to starting therapy, the more likely that the dog will be well managed with cyclosporine drops alone. Absolute sicca may be associated with extensive fibrosis of the tear glands, leaving little tissue for stimulation or repair.
Cyclosporine is effective in the management of German Shepherd Pannus or chronic superficial keratitis in the dog. This condition is an immune disease of the cornea and likely is interleukin mediated. Cyclosporine may be preferred for the treatment of pannus because of the lack of systemic side effects noted in dogs with chronic topical administration of cyclosporine. Chronic topical corticosteroid treatment is associated with biochemical changes in the blood of large and small dogs.
Cyclosporine has been tried in the management of the rare case of keratoconjunctivitis sicca in the cat. Dry eye in cats is usually associated with herpes virus destruction of lacrimal epithelial cells and or stenosis of the ductules or openings of the ductules due to chronic viral conjunctivitis. Preliminary results have not been promising. Topical cyclosporine often aggravates ophthalmic herpes virus infections in people. Cyclosporine has not shown promising effects in the management of feline eosinophilic keratitis, a condition now thought to be related to chronic stromal herpes virus infection in cats.
Suggested Dosages/Precautions/Adverse Effects – Cyclosporine is initiated generally as the first course of therapy for confirmed dry eye cases in the dog. The topical half life of cyclosporine is about 8 hours and most canine cases of KCS are managed with twice daily therapy with 0.2% ointment (Optimmune®). Three times a day therapy has been employed during the initial phases of treatment in more difficult or slow responding cases. For some uncertain reason (reversal of lacrimal adenitis‡ reorganization of lacrimal epithelial cell function‡ formation of secretory granules‡ tear production) 3-8 weeks of therapy are necessary before a dramatic increase in the Schirmer tear test becomes evident. Patients are generally maintained for life on cyclosporine ophthalmic once or twice daily depending on the response. Discontinuation of therapy is usually associated with the return of clinical signs of KCS within a few days. Reinstitution of therapy at this time, is usually associated with an almost immediate return of tear production (versus the initial lag phase noted). This likely is related to the degree of inflammatory disease noted with short discontinuation of therapy versus that present initially, prior to the diagnosis of KCS.
If tear production is very low, cyclosporine is often used in combination with artificial tears during the initial phases of therapy. Once tear production is improved, artificial tears can generally be removed completely or their frequency reduced in the treatment plan. After treatment is initiated, reevaluation of tear production in one month is recommended. If ulcerative keratitis complicates keratoconjunctivitis sicca in the dog, more frequent evaluation is necessary. Cyclosporine, although an immunomodulating agent, is considered safe in the face of ulcerative keratitis, with concurrent antibiotic therapy. Caution is advised, however.
When cyclosporin is delivered topically, no systemic toxicity has been noted in dogs given this drug chronically. This is probably associated with the poor absorption of this drug across the GI tract and because it is delivered to the eye at very low concentrations which even if 100% absorbed, when divided over the body weight of the dog is well below even the therapeutic dose. Advanced detection methods have made it possible to measure trace levels of cyclosporine in the blood of dogs being topically treated for dry eye. The clinical implications of this finding is uncertain at this time.
Dosage Forms/Preparations/FDA Approval Status – Optimmune® ointment is the approved formulation of topical cyclosporine for the management of dry eye in dogs. Compounding of topical cyclosporine drops was popular before the introduction, approval, and marketing of Optimmune® ointment. Clinicians persistently using compounded formulations of cyclosporine eye drops may be outside of expected ethical and legal standards of practice except under very specific situations. The use of commercially available ophthalmic products instead of compounded medications is highly recommended. Optimmune® is first applied 2 or 3 times daily and frequency of daily application is adjusted based on clinical response.
Veterinary-Approved Products:
Cyclosporine Ophthalmic Ointment 0.2%; Optimmune® (Schering-Plough); (Rx)
Human-Approved Products:
Orphan products are available for human uses.
ARTIFICIAL TEAR PRODUCTS; OCULAR LUBRICANTS
Indications/Pharmacology – Artificial tear solutions are aqueous isotonic, pH buffered viscous solutions that serve as a lubricant for dry eyes and associated eye irritation due to dry eye syndromes. They are often useful adjuncts in keratoconjunctivitis sicca in dogs early in cyclosporine therapy.
Ocular lubricants are white petrolatum-based products that serve to lubricate and protect eyes. They are particularly useful during anesthetic procedures where animals’ eyes may remain open and during which time tear production is dramatically reduced.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products:
There are a plethora of products available with a variety of formulations and trade names. All are OTC. Some commonly known products include:Artificial Tear Products (Methylcellulose-based): Adsorbotear® (Alcon); Comfort Tears® (Pilkington Barnes Hind); Isopto-Tears® (Alcon); Tears Naturale® (Alcon); Lacril® (Allergan)
Artificial Tear Products (Polyvinyl Alcohol-based): Hypotears® (Iolab); Liquifilm Tears (Allergan); Tears Plus® (Allergan)
Artificial Tear Products (Glycerin-based): Dry Eye Therapy® (Bausch & Lomb); Eye Lube A (Optopics)
Ocular Lubricants (Petrolatum-based): Lacri-Lube® S.O.P. (Allergan); Akwa Tears® (Akorn)
Indications/Pharmacology – Sterile isotonic solutions are used for flushing the nasolacrimal system and for removing debris from the eye. They are also used to remove excess stain after diagnostic staining of the cornea. Sterile lactated Ringer’s solution (LRS) is well tolerated by the surface of the eye as is a balanced salt solution (BSS). Extraocular irrigating solutions may contain preservatives. Intraocular irrigating solutions (used during surgical procedures) do not contain preservatives and also contain electrolytes that are required for normal cell function.
Suggested Dosages/Precautions/Adverse Effects – Extraocular: Use to flush eye as necessary; control rate of flow by exerting pressure on bottle. Intraocular: Refer to both established practices for each surgical procedure as well as the specific manufacturers’ recommendations.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products:
Eye Rinse® (Butler); (OTC): Contains: water, boric acid, zinc sulfate, glycerin, camphor. Note: This product is not labeled to be used as an irrigant per se, but as an aid in cleaning the eye and removing eye stains.
Human-Approved Products:
Common trade name products for extraocular irrigation: AK-Rinse® (Akorn), Blinx® (Pilkington Barnes Hind), Collyrium for Fresh Eyes Eye Wash® (Wyeth-Ayerst), Dacriose® (Iolab), Eye Irrigating Solution® (Rugby), Eye-Stream® (Alcon), Eye Wash® (several manufacturers), Eye Irrigating Wash® (Roberts Hauck), Irrigate Eye Wash® (Optopics),Optigene® (Pfeiffer), Star-Optic Eye Wash® (Stellar), Visual-Eyes ® (Optopics). All are OTC.
Common trade name products for intraocular irrigation: Note: Most of these products contain Balanced Salt Solution (BSS) = NaCl 0.64%, KCl 0.075%, CaCl2•2H20 0.048%, MgCl2•6H20 0.03%, Na acetate trihydrate 0.39%, sodium citrate dihydrate 0.17%, sodium hydroxide and/or hydrochloric acid to adjust pH, and water: Balanced Salt Solution (various manufacturers), BSS® (Alcon), Iocare Balanced Salt Solution® (Iolab); All are Rx.
BSS + solutions that also contain dextrose, glutathione, bicarbonate, phosphate are also available as: BSS Plus® (Alcon) and AMO Endosol Extra® (Allergan); All are Rx.
Diagnostics
Fluorescein Sodium (Ophthalmic)
Indications/Pharmacology – Fluorescein sodium is a yellow water soluble dye. It is used most commonly to delineate full thickness loss of corneal epithelium. In this instance it will stain the corneal stroma. The epithelium is not stained because its outer lipid cell membrane repels the stain. Descemet’s membrane will not stain with fluorescein stain and this is used to indicate descemetocele formation, an ocular emergency.
Fluorescein stain is applied to the precorneal tear film in dogs and cats and the break-up of this stain with time, as observed through a slit lamp biomicroscope using a cobalt blue light source, is used to determine the tear film break-up time (normal 19s), an indicator of tear film quality.
Fluorescein stain is applied to the tear film of dogs to determine patency of the nasolacrimal outflow system. The normal wait time is 2-5 minutes in dogs and up to 10 minutes in cats. A positive test indicates patency of the system. A negative test is not indicative of disease as the test is negative in a large percentage of normal animals. Fluorescein stain, then, can be added to irrigating solution to flush the nasolacrimal system, making detecting the irrigation solution at the nose more obvious during flushing of the system.
Suggested Dosages/Precautions/Adverse Effects – Fluorescein stain is applied by dropping a drop of irrigating solution onto the sterile strip and then allowing the drop to fall on the eye. The strip should not contact the cornea or it will cause false positive stain retention at the site of contact with the epithelial cells. After a few seconds, the excess fluorescein is irrigated from the eye, staining areas of full thickness epithelial loss.
Conjunctival or corneal epithelial cells for fluorescent antibody testing should be collected prior to application of fluorescein stain, which can cause a false positive test for several days after application of the stain.
Fluorescein may rarely cause hypersensitivity reactions. Temporary staining of fur and skin may result. Do not use during intraocular surgery.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products: Sterile strips of paper impregnated with fluorescein sodium are the most commonly used form in veterinary medicine. Solutions (2%) of fluorescein are available, however they are not popular following one study indicating that Pseudomonas is readily grown in such solutions. Injectable products are also available (for ophthalmic angiography), but are not routinely used in veterinary medicine.
Fluorescein Sodium Strips 0.6 mg Ful-Glo® (Barnes Hind); 1 mg Fluorets® (Akorn), Fluor-I-Strip®-A.T. (W-A); 9 mg Fluor-I-Strip® (W-A); All Rx.
Indications/Pharmacology – Rose Bengal is a vital stain and stains dead epithelial cells and mucus. Full thickness loss of the corneal epithelium is not necessary (only dead cells need be present) to obtain Rose Bengal stain uptake. It does not stain epithelial defects and does not pass into intercellular spaces.
Rose Bengal stain is most commonly employed in the detection of the presence of viral keratitis in the cat. Because feline herpes virus tends to infect one cell, moving then to an adjacent cell (causing the so called dendritic tracts in the cornea) without full thickness loss of corneal epithelium initially, Rose Bengal is an ideal diagnostic agent for this infection. Rose Bengal can also be used to detect damaged corneal epithelium on the dorsal cornea in early cases of keratitis sicca. Rose Bengal stain is virucidal although no information is available relative to its use as a therapeutic agent.
Suggested Dosages/Precautions/Adverse Effects – Rose Bengal is applied as a solution (1-2 drops in conjunctival sac before examination) or from an impregnated strip (saturate tip of strip with sterile irrigating solution; touch bulbar conjunctiva or lower fornix with moistened strip; cause patient to blink several times to distribute the stain).
Rose Bengal is apparently toxic to the cornea and conjunctiva and should be thoroughly flushed from the eye after use to prevent irritation. Hypersensitivity reactions are possible. May stain clothing.
Dosage Forms/Preparations/FDA Approval Status –
Veterinary-Approved Products: None
Human-Approved Products:
Rose Bengal Solution 1% in 5 ml dropper bottles (Akorn); Rx
Rose Bengal Strips 1.3 mg per strip; Rosets® (Akorn), Generic (Barnes-Hind); Rx