Diagnosis: The tentative diagnosis is Acute Congestive Glaucoma. The combination of a painful, red, cloudy eye with a fixed, dilated pupil and acute vision loss is highly suggestive of a rapid and severe increase in intraocular pressure. More information on this condition can be found at the
DDx: The main differential diagnoses for a painful red eye are severe anterior uveitis and a deep corneal abscess or melting ulcer. However, uveitis typically presents with a constricted (miotic) pupil, and an ulcer would be visible with a fluorescein stain.
Diagnostic tests: This is a true ophthalmic emergency, and diagnosis must be confirmed immediately.
Intraocular Pressure (IOP) measurement (Tonometry): This is the definitive diagnostic test. The pressure in both eyes was measured with a rebound tonometer (TonoVet/Tono-Pen).
Result OD (affected eye): 68 mmHg [Ref: 15-25 mmHg]
Result OS (normal eye): 22 mmHg
The extremely high IOP in the right eye confirms acute glaucoma.
Fluorescein stain: A stain was applied to the right eye to rule out a concurrent corneal ulcer before starting aggressive topical therapy. The test was negative.
Definitive diagnosis: Primary Acute Congestive Glaucoma. Given the breed (Cocker Spaniel) and the normal appearance of the other eye, a primary (inherited) cause is most likely.
Treatment:
The goal is to rapidly reduce the IOP to save the optic nerve and preserve vision.
Emergency Medical Treatment:
An IV catheter was placed and a slow IV infusion of Mannitol (an osmotic diuretic) was started to rapidly draw fluid out of the eye.
A combination of topical medications was started in the right eye:
Latanoprost: A prostaglandin analog to increase uveoscleral outflow.
One drop was given immediately. (Note: This is contraindicated if glaucoma is secondary to uveitis). Dorzolamide-Timolol combination: A carbonic anhydrase inhibitor and a beta-blocker to decrease aqueous humor production. One drop was given, to be continued every 8 hours.
The IOP was rechecked every 30-60 minutes.
Long-term and Prophylactic Treatment:
Once the IOP in the right eye was reduced to < 25 mmHg, the dog was started on a long-term topical medication plan (e.g., Dorzolamide-Timolol) to maintain normal pressure.
Prophylactic therapy (e.g., a single daily drop of a beta-blocker like Timolol) was started in the left ("good") eye, as primary glaucoma almost always becomes bilateral.
The owner was informed that medical therapy often fails over time and that the gold standard for long-term control is referral to a veterinary ophthalmologist for surgical options (e.g., laser cyclophotocoagulation or a gonioimplant).
