Equine Intraocular Diseases (not done)

What is iris hyoplasia?

Dark are of iris bulging forward usually dorsal due to a thinned iris stroma

What do need to rule out with iris hypoplasia?

Melanoma

Iris hypoplasia

What are corpora nigra cysts?

May enlarge over time and should transilluminate

Rule out neoplasia

How do you treat corpora nigra cysts?

Benign neglect

If vision compromised refer for diode laser

Corpora nigra cyst

What is the most common iris neoplasia?

Melanoma (esp in gray horses)

Ho do you identify iris neoplasia?

Dark mass in anterior chamber

Need to use US to differentiate from cyst

How do you treat iris neoplasia?

Enucleation once secondary glaucoma develops

Iris neoplasia

What is the most common cause of equine blindness?

Equine recurrent uveitis

What are causes of uveitis?

Trauma: blunt of penetrating injury

Infectious: bacteria, viral, parasites

Misc: endotoxemia, septicemia, tooth root abscess, neoplasia, reflex uveitis

What are C/S of uveitis?

Blepharospasm, epiphora, conjunctival hyperemia, aqueous flare, miosis, a ton of other lol

How do you diagnose acute uveitis?

Rule out primary corneal disease with a fluorescein stain

What are other names of equine recurrent uveitis (ERU)?

Moon blindness or periodic ophthalmia

What is the prevalence of ERU (equine recurrent uveitis)?

8-25% of all horses

What do you need to tell owners if their horse gets ERU?

Not every case of uveitis leads to ERU but need to tell owner risk of recurrence or opposite eye risk

DO NOT LET THEM TREAT WITHOUT A VET EXAM

When can you classify ERU?

2 or more observed episodes of uveitis

T/F ERU can be uni or bilateral?

True

What is the pathogenesis of ERU?

Immune mediated, probably exposed to leptospirosis and the antibodies then recognize self-antigens and will attack the eye

Chronic uveitis (ERU) leads to brown pigment

What are end stage ERU lesions?

Blindness, phthisis bulbi, dyscoria/posterior synechia, cataract, lens luxation, retinal detachment

What causes glaucoma in horses?

Very uncommon, usually secondary to uveitis

How do you diagnose glaucoma?

Elevated IOP

PLR deficits or fixed and dilated pupil

Buphthalmos

Corneal changes (Haabs stria)

Optic nerve changes

How do you treat glaucoma?

Topical carbonic anhydrase inhibitors

Topical beta-blockers

Uveitis treatment

Sx: laser treatment of ciliary body, end stage options for blind or painful eyes are enucleation or chemical ablation

What breeds are predisposed to cataracts?

Belgian, thoroughbred, QH

Why do horses usually get cataracts?

Usually secondary to uveitis, can also be secondary to trauma, due to old age, or inherited

When should you do surgery on cataracts?

Young foals are preferred

NOT recommended for cataracts secondary to ERU