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67 Cards in this Set
- Front
- Back
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Describe the three layers of the cornea.
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Lipid soluble epithelium
Water soluble stroma Lipid soluble Descemet's membrane |
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What size molecule is better for getting into the cornea-- larger or smaller?
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Smaller
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True or false: Ionic drugs are most effective at their highest concentration.
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False
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This medication form tends to be less irritating, has shorter corneal contact time, and more systemic absorption.
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Drops
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This medication form is the best one for large animals, but tend to cause greater irritation. There is a longer contact time on the cornea, and less systemic absorption.
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Ointment
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DMSO may be used as a carrier molecule to carry other drugs into the cornea; however, this is a major ophthalmic side effect.
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Corneal sloughing
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How can ophthalmic drugs be systemically absorbed?
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Absorbed across corneal vasculature
Runs down nasolacrimal duct and gets licked |
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Most common way of administering ophthalmic drugs
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Periodic administration
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The lavage system of ophthalmic drug administration is particularly useful for this species
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Horse
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How do subconjunctival injections work?
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Repositol effect under conjunctiva
Drug leaks back out gradually into the precorneal tear film Increases local drug concentration over time |
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Problems with subconjunctival injection
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Irritation
Risk of globe puncture Can't undo if the condition of the eye changes and drug becomes CI |
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Only way to treat diseases of the retina or choroid.
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Systemic administration
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How effective is systemic administration of a drug in treating a local ocular disease?
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Less effective than topical administration
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Uses for intraocular durg administration in veterinary medicine
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Intraocular surgical use
Endophthalmitis Treat absolute glaucoma |
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"Shotgun drug" combo also known as triple antibiotic ointment
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Neomycin (Aminoglycoside, G-)
Bacitracin (G+) Polymyxin B (G-) |
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Broad spectrum antibiotic that also gets chlamydial and rickettsial organisms. Penetrates the cornea well.
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Chloramphenicol
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Concern with using chloramphenicol in human medicine.
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Aplastic anemia
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Risk of aplastic anemia with topical chloramphenicol use.
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Negligible
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This drug has a good gram-negative spectrum and will get many Pseudomonas isolates. Gets some Gram +, especially Staphs but not Strep. Available for ophthalmic use in both drop and ointment form.
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Gentamycin
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Drug of choice for Chlamydia or Rickettsial diseases. May be irritating as a topical medication.
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Tetracycline
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Commonly used fluoroquinolone in human medicine. Broad spectrum and expensive.
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Ciprofloxacin
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List some antiviral agents commonly uned to treat ocular herpes in cats.
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Trifluorothymidine
Vidarabine Cidofovir Famcyclovir Lysine Interferon Dilute betadine solution |
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Supposedly one of the best antivirals available.
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Trifluorothymidine
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Ties up arginine during viral replication, used for long term therapy in chronic herpes cats.
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Lysine
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May be used to stimulate local immunity and decrease recrudescence in cases of feline herpes.
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Interferon
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Bacteriostatic/virostatic treatment used in kittens with herpetic keratoconjunctivitis.
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Dilute betadine solution
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Anti-mycotic drugs are most commonly used to treat fungal keratitis in...
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Horses
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List three anti-mycotic agents used to treat fungal keratitis in horses.
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Pimaricin
Miconazole Silver sulfadiazine |
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Only drug approved for human use or animal use as an antifungal agent.
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Pimaricin
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Does miconazole penetrate an intact cornea?
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Yes
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Does pimaricin penetrate an intact cornea?
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No
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Available as a 1% burn cream, effective against many bacteria and fungi.
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Silver sulfadiazine
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Anti-mycotic solution used to swab ulcer beds either at full strength or diluted to a 1% solution.
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10% povidone iodine
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In which two groups are NSAIDs typically used to treat ocular disorders?
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Horses
Diabetic dogs |
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These drugs inhibit the release of arachidonic acid and are immunosuppresive.
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Steroids
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Adverse side effects of ophthalmic steroid use.
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Inhibit ulcer healing
Potentiate corneal proteolytic enzyme activity Lipid degeneration of the cornea Suppression of adrenal-pituitary axis with systemic use |
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Uses of opththalmic steroids
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Reduce inflammation after surgery or in non-pyogenic states
Reduce inflammation from allergies or hypersensitivity Reduce corneal neovascularization and scarring during healing |
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Contraindications of ophthalmic steroid use
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Surface ocular infection
Corneal ulceration (topical CI) |
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List the two most effective anti-inflammatory topical ophthalmic drugs. They are both labeled for human use.
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Prednisolone suspension
Dexamethosone solution or ointment |
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Why must systemic steroids be used with care in treating ophthalmic conditions in the horse?
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Risk of laminitis
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Used as a topical immunosuppressive agent in veterinary medicine to treat KCS and various causes of keratitis.
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Cyclosporine-A
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Immunosuppressive agent used to treat cell-mediated hypersensitivity. Addresses uveitis and surface ocular disorders in dogs.
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Azathiaprine
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Side effects of azathiaprine usage.
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Bone marrow suppression
Hepatotoxicity |
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Parasympatholytic agent that passively dilates the pupil by paralyzing the iridial sphincter.
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Atropine
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How long does atropine's effect last in dogs? In cats?
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Dogs- 2-3 days
Cats- Up to 1 week |
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Most common mydriatic/cycloplegic agent used in ophthamology.
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Atropine
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This drug is used to treat anterior uveitis, pupil dilation for surgery, dilation of pupil to enhance vision around a cataract, or to try to break down posterior synechia.
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Atropine
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Side effects of atropine use in the eye.
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Decreased tear production
Acute attack of angle closure glaucoma Colic in horses from ileus |
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What does pilocarpine do to the eye?
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Direct constriction of pupil
(Mimics Ach) |
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Pilocarpine is used primarily to treat this disease
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Primary angle closure glaucoma
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Downside of pilocarpine use
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Very irritating
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How does demecarium bromide cause miosis?
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Acetylcholinesterase inhibition in the eye
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Why would you want to constrict the pupil in a narrow/closed angle glaucoma patient?
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Opens iridiocorneal angle to enhance aqueous outflow
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This drug class is used to decrease active production of aqueous humor from the ciliary body. Given systemically as a pill.
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Carbonic anhydrase inhibitors
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Ophthalmic use for beta-blockers like timolol.
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Decrease active aqueous humor production
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Drug class used for the emergency treatment of glaucoma
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Osmotic diuretics (glycerin USP and mannitol)
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This drug class affects the iridial sphincter musculature in dogs to cause miosis and lower intraocular pressure.
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Prostaglandin analogs
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This multi-use chemical can act like a cauterizing agent--used to sterilize a wound, enhance scar tissue formation, or enhance corneal neovascularization.
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Straight betadine
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Used to inhibit proteolytic enzymes in corneal ulceration to inhibit "meltdown"
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Anti-collagenase agents
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List some anti-collagenase drugs used in veterinary medicine to inhibit melting ulcers.
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Acetylcysteine
Serum NaEDTA Dilute Betadine Systemic tetracycline |
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Used to cleanse debris from the surface of the eye--> can include agnets like saline, LRS, or special cocktails.
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Eyewash
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These solutions are comprised of a balanced, tear-like component that mimics precorneal tear-film. Good ones have agents to increase viscosity.
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Lubricants
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This drug class is used in the eye ONLY as a diagnostic tool and NEVER therapeutically.
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Topical anesthetics
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These drugs are epitheliotoxic and can contribute to corneal ulcerations.
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Local anesthetics
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Most common local anesthetic available for ophthalmic use in veterinary medicine.
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Proparacaine
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Water-soluble stain to pinpoint corneal ulcers.
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Na fluorescein
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This dye stains necrotic cells red; good for localizing dry spots on the cornea and diagnosis herpes keratitis in cats
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Rose bengal
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