Acute Glaucoma in Small Animals

Mechanism: Elevated pressure leads to pain and degenerative damage to the optic nerve.

Primary Glaucoma: Caused by a primary defect in the iridocorneal drainage angle.

• Angle Closure: Sudden collapse of the angle leading to rapid IOP rise.

• Open-Angle: Slow rise over time (e.g., ADAMTS10 mutation in Beagles).

Secondary Glaucoma: Results from underlying conditions such as anterior uveitis, lens luxation, or intraocular neoplasia.

Primary Objective: Rapidly lower IOP to preserve as much vision as possible.

Short-Term (Dogs):

• Topical Prostaglandin Analogs: (e.g., Latanoprost). Critical: Assess lens position first; miosis can trap an anteriorly luxated lens and worsen IOP.

• Osmotics: Systemic Mannitol (IV) or Glycerin (PO, emergency home use; avoid in diabetics).

• Carbonic Anhydrase Inhibitors: Topical or systemic.

Cats: Options are limited; prostaglandin analogs are often ineffective or irritating.

If Vision is Present: Consider cyclophotocoagulation (endolaser) or anterior chamber shunts.

If Vision is Absent: Consider enucleation, evisceration, or chemical ablation (intravitreal cidofovir).

• Contraindication (Cats): Avoid intravitreal gentamicin due to the risk of malignant ocular tumors.

Prophylaxis: Treat the unaffected eye in dogs with primary glaucoma using demecarium bromide or timolol plus a topical steroid to prevent an attack.