Ophthalmic Drugs

Question 1

Parasympathetic nervous system effects on the eye

Answer 1

Miosis = contraction of the iris sphincter

Contraction of the ciliary body =lens accommodation for near vision

Question 2

Sympathetic nervous system effects on the eye

Answer 2

Relaxation of the ciliary body = lens accomodation for far vision
Variable mydriasis = contraction of the iris dilator muscles
Aqueous humor formation

Question 3

MOA of Mitotics

Answer 3

=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

Question 4

Mitotic drugs

Answer 4

=Parasympthomimetics
Pilocarpine
Physostigmine and Demecarium
Echothiophate

Question 5

Pilocarpine

Answer 5

Direct acting parasympathomimetic
Used for diagnosis of parasympathetic lesions
Commonly used in the treatment of glaucoma, or KCS (keratoconjunctivits sicca ‘dry eye’)

Question 6

Physostigimine and Demecarium

Answer 6

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

Question 7

Echothiophage

Answer 7

Indirect acting parasympathomimetic (irreversible cholinesterase inhibitor)
Very long duration of miosis

Question 8

Mydriatic drugs

Answer 8

=Parasympatholytics
Atropine
Tropicamide
Phenylephrine

Question 9

Atropine

• Classification
• Ophthalmic indications

Answer 9

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

Question 10

Atropine

-Cautions

Answer 10

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)

Question 11

Tropicamide

• Classification
• Ophthalmic indications

Answer 11

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

Question 12

Tropicamide

-Caustions

Answer 12

Less effective pain control than atropine
Less bitter but can still cause cats to hypersalivate
Avoid in glaucoma

Question 13

Phenylephrine

Answer 13

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

Question 14

Drugs that reduce aqueous humor formation and/or improve aqueous outflow

Answer 14

Brimonidine = alpha agonist
Timolol = beta antagonist
Dorzolamide, Brinzolamide = Carbonic anhydrase inhibitors
Latanoprost = Prostaglandin analogs

Question 15

Brimonidine

Answer 15

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

Question 16

Timolol

Answer 16

Ophthalmic nonselective beta antagonist
Used to prevent glaucoma in contralateral eye
Decreases aqueous formation

Question 17

Dorzolamide and Brinzolamide

Answer 17

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

Question 18

Latanoprost

Answer 18

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

Question 19

Drugs for tear production

Answer 19

Artificial tears and lubricants

Topical Immunomodulators - Cyclosporine and Tacrolimus

Question 20

Cyclosporine

Answer 20

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

Question 21

Tarolimus

Answer 21

Topical Immunomodulators, Lacrimogenic agents
Decreases T cell activation
Alternative to cyclosporine, works on some patients who are not responsive to cyclosporine

Question 22

Anti-inflammatory drugs

Answer 22

Topical Glucocorticoids = Dexamethaone, Prednisolone

Topical NSAIDs = Flubiprofen, Diclofenac

Question 23

Dexamethasone, Prednisolone

Answer 23

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

Question 24

Flurbiprofen, Diclofenac

Answer 24

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

Question 25

Ophthalmic Topical Anesthetic

Answer 25

MOA same as other local anesthetics - blocks Na+ channels to prevent axonal depolarization
Used to decrease corneal sensation to allow diagnostic evaluation

Question 26

3 Antiviral Agents

Answer 26

Gancyclovir = topical
Famcyclovir = systemic
L-lysine oral supplementation
Most often used to manage feline viral infections and generally for more severe cases