Glaucoma in Pets: The Silent Threat to Vision
Glaucoma is elevated pressure inside the eye that can cause blindness within hours. Recognizing the signs early can save your pet's sight.
Glaucoma occurs when fluid builds up inside the eye, increasing intraocular pressure (IOP). This pressure damages the optic nerve and retina, leading to irreversible blindness. It's a true veterinary emergency requiring immediate intervention.
Key Points
- Normal IOP is 15-25 mmHg; glaucoma occurs when IOP exceeds 30 mmHg
- Primary glaucoma is inherited in breeds like Beagles, Basset Hounds, and Siamese cats
- Secondary glaucoma follows cataracts, uveitis, or lens luxation
- Acute glaucoma causes sudden blindness and eye pain within hours
- Treatment includes drops, oral medication, and surgery to reduce pressure
- The opposite eye is at high risk even if currently normal
How Glaucoma Develops
Aqueous humor is the fluid that nourishes the eye and maintains its shape. It's produced by the ciliary body and drains through the iridocorneal angle. When drainage is blocked — either genetically (primary) or due to disease/inflammation (secondary) — pressure builds. The elevated pressure compresses blood vessels supplying the retina and optic nerve, causing cell death and vision loss.
Recognizing an Emergency
Acute glaucoma presents as a suddenly red, painful, cloudy eye. The cornea may appear bluish. The pupil is often dilated and unresponsive to light. Your pet may squint, tear excessively, or hide due to pain. The eye may bulge slightly. Some pets develop headache-like behavior — restless, head-pressing, or decreased appetite. Chronic glaucoma causes the eye to enlarge (buphthalmos) but is less painful.
Diagnosis & Monitoring
Your veterinarian measures IOP with a tonometer (Tono-Pen or Tonovet). Gonioscopy evaluates the drainage angle. Ultrasound examines the lens position and retina. Blood tests rule out systemic causes. If one eye is affected, the other eye is monitored every 3-6 months. IOP is measured in both eyes even if only one appears affected.
Treatment & Management
Emergency treatment includes topical carbonic anhydrase inhibitors (dorzolamide), beta-blockers (timolol), and prostaglandin analogs (latanoprost). Oral mannitol or hyperosmotic agents may be used for severe spikes. Long-term management requires lifelong drops, often multiple times daily. Surgical options include laser cyclophotocoagulation, gonioimplants, or enucleation if vision is permanently lost.
When to See a Vet Immediately
- The eye suddenly appears red, cloudy, or bluish
- Your pet is squinting or showing signs of eye pain
- The pupil is dilated and doesn't respond to light
- The eye seems larger than the other
- Your pet suddenly bumps into things
How RVC Can Help
This article is for educational purposes only and does not replace professional veterinary advice. If your pet is showing any symptoms, please contact Royal Veterinary Center immediately at +853 6677 6611.