Ophthalmic Drugs Flashcards
Parasympathetic nervous system effects on the eye
Miosis = contraction of the iris sphincter
Contraction of the ciliary body =lens accommodation for near vision
Sympathetic nervous system effects on the eye
Relaxation of the ciliary body = lens accomodation for far vision
Variable mydriasis = contraction of the iris dilator muscles
Aqueous humor formation
MOA of Mitotics
=Parasympathomimetics
Generally cause pupil constriction which opens the drainage angle
Contracts the ciliary body muscle which lifts the iris and improves aqueous outflow
Don’t use if anterior uveitis or anterior lens luxation
Mitotic drugs
=Parasympthomimetics
Pilocarpine
Physostigmine and Demecarium
Echothiophate
Pilocarpine
Direct acting parasympathomimetic
Used for diagnosis of parasympathetic lesions
Commonly used in the treatment of glaucoma, or KCS (keratoconjunctivits sicca ‘dry eye’)
Physostigimine and Demecarium
Indirect acting parasympathomimetics (reversible cholinesterase inhibitor)
Increases uveoscleral drainage
Dememcarium - preventative in contralateral eye
Physostigmine - readily cross BBB (seizures), caution with absorption in small animals
Echothiophage
Indirect acting parasympathomimetic (irreversible cholinesterase inhibitor)
Very long duration of miosis
Mydriatic drugs
=Parasympatholytics
Atropine
Tropicamide
Phenylephrine
Atropine
- Classification
- Ophthalmic indications
Direct acting parasympatholytic (anticholinergic)
Causes mydriasis and cycloplegia (blurred vision)
Ophthalmic indications - to reduce pain associated with corneal or iris disease (uveitis), can break up synechiae in uveitis
Atropine
-Cautions
Do not use in primary glaucoma!
Generally minimal systemic absorption
Cycloplegia can causes horses to panic
Very bitter taste (cats froth at the mouth when drops are used)
Tropicamide
- Classification
- Ophthalmic indications
Direct acting parasympatholytic
Causes mydriasis and cycloplegia
Faster onset, shorter duration than atropine
Ophthalmic indications - used to dilate the pupil for ophthalmic (funduscopic) exam; used to prevent adhesions after cataract surgery
Tropicamide
-Caustions
Less effective pain control than atropine
Less bitter but can still cause cats to hypersalivate
Avoid in glaucoma
Phenylephrine
Causes mydriasis through contraction of the iris dilator muscle (alpha-1 agonist)
Perioperative use in cataract surgery (reduction of posterior synechiae formation)
Most often used to help diagnose and treat Horner’s syndrome, then as a primary mydriatic
Drugs that reduce aqueous humor formation and/or improve aqueous outflow
Brimonidine = alpha agonist
Timolol = beta antagonist
Dorzolamide, Brinzolamide = Carbonic anhydrase inhibitors
Latanoprost = Prostaglandin analogs
Brimonidine
Ophthalmic alpha-2 agonist that reduces IOP Used in dogs for treatment of glaucoma; reduces aqueous production and improves outflow Other agents (Carbonic anhydrase inhibitors) more likely to be used in treatment of glaucoma
Timolol
Ophthalmic nonselective beta antagonist
Used to prevent glaucoma in contralateral eye
Decreases aqueous formation
Dorzolamide and Brinzolamide
Topical Carbonic Anhydrase Inhibitors
Decreases aqueous humor production resulting in lower IOP
Sulfonamide derivatives (caution if hypersensitivity to sulfa)
Dorzolamide may sting more than Brinzolamide
Latanoprost
Topical Prostaglandin Analogs
Prostaglandin analogs increases uveoscleral outflow by stimulating FP (prostaglanding) receptors in the eye
Used topically to treat glaucoma and reduce IOP in dogs (not effective in cats, horses)
Often used for emergency management
Drugs for tear production
Artificial tears and lubricants
Topical Immunomodulators - Cyclosporine and Tacrolimus
Cyclosporine
Topical Immunomodulators, Lacrimogenic agents
Used in the treatment of canine KCS (keratoconjunctivitis sicca)
BID topical application, may be lifelong
Monitor by measuring tear production (Schirmer tear test)
Increases tear production and provides local immunosuppression
Tarolimus
Topical Immunomodulators, Lacrimogenic agents
Decreases T cell activation
Alternative to cyclosporine, works on some patients who are not responsive to cyclosporine
Anti-inflammatory drugs
Topical Glucocorticoids = Dexamethaone, Prednisolone
Topical NSAIDs = Flubiprofen, Diclofenac
Dexamethasone, Prednisolone
Topical Glucocorticoids
Used to manage inflammatory and immune mediated conditions (non-infectious keratitis, uveitis)
Even with local administration, there is some systemic absorption
Contraindicated if corneal ulcer, infection, or diabetes
Flurbiprofen, Diclofenac
Topical NSAIDs
Use when a higher local concentration and lower systemic concentration is desired
Used in management of uveitis and some keratitis
May be used to manage inflammation associated with cataracts
Contraindicated if corneal ulceration, glaucoma, or coagulopathies
Ophthalmic Topical Anesthetic
MOA same as other local anesthetics - blocks Na+ channels to prevent axonal depolarization
Used to decrease corneal sensation to allow diagnostic evaluation
3 Antiviral Agents
Gancyclovir = topical
Famcyclovir = systemic
L-lysine oral supplementation
Most often used to manage feline viral infections and generally for more severe cases
