Treating glaucoma in the emergency room

Robert Swinger, DACVO, DVM, founder of Animal Eye Guys clinics in South Florida, noted that 2 types of glaucoma cases typically present for emergency care. "The one that went acutely blind this morning, and it’s painful, and the eye is red, and it was normal 12 hours ago… or the eye that comes in and is twice as big as the other eye and has been blind for weeks,” he said, during his recent lecture on ophthalmic emergencies at the 2024 American Veterinary Medical Association Convention in Austin, Texas. “We’re going to treat those very differently.

“The patient that is painful, has flare, is red, has edema, that maybe has a normal optic nerve – the acute case, we’re going to treat aggressively. We want that pressure to go down within the next 2 hours to try and get vision back. The buphthalmic eye with Haab’s striae, terminal vessels, small optic nerve cupping, that ship has sailed, so our goals for that patient are comfort. We want to get the pressure down so that their headache goes away, so that they feel good,” Swinger continued.

The vast differences in the ways in which glaucoma shows itself, and theway it should be approached by medical professionals, is exemplified by the scenario which Swinger has outlined. To further that same point, Swinger went on to explain that clinical signs can be on a sliding scale and can vary depending on glaucoma stage. That said, associated signs can include episcleral vessel congestion, buphthalmia, corneal edema, epiphora, mid/deep stromal corneal vessels, Haab’s striae, aqueous flare, mydriasis, lens subluxation/luxation, and retinal or optic nerve degeneration.

During his lecture, Swinger shared the importance of determining a cause and identifying which classification of glaucoma any given patient may have, as any following therapy will be dependent on it. Glaucoma should be classified as either primary, congenital, or secondary.

A significant portion of the diagnosis with glaucoma comes down to intraocular pressure (IOP) exceeding 25mmHg, though variables including patient’s age, clinical signs, patient positioning, and the type of tonometry instrument utilized should be considered. IOP tends to ride higher in younger patients. Added pressure to patient’s neck and eyelids should be avoided, tight collars and restraints should be removed, and patient should ideally be in sternal recumbency.

As Swinger explained, there are 2 methods for medical therapy. Firstly, there’s the route of decreasing fluid production through the implementation of carbonic anhydrase inhibitors (topical dorzolamide or oral methazolamide) or beta blockers (timolol). The other option aims to increase fluid outflow through use of prostaglandin analogues or parasympathomimetic drugs.

Introducing treatment options, Swinger explained that the goal moving forward is not to cure patients. “There’s no cure for glaucoma. Once you have it, you generally have it.”

However, treatment goals should be focused on preserving vision, reducing IOP, and providing comfort to the patient. If pressure cannot be managed, next steps can include ciliary body ablation, enucleation, or intrascleral prosthesis, though Swinger noted that intrascleral prosthesis is outdated. “We were really doing those, I think, more for us than the dog,” he said.

As for followups, Swinger recommended rechecking the IOP 1-3 days following the initial exam. From there, if it’s controlled, he recommended rechecking IOP every 1-2 weeks, in 1 month, and then every 2-3 months going forward. If it’s not controlled, however, consider additional glaucoma medications. If the patient retains their vision with primary glaucoma, but it isn’t controlled, consider potential surgery with an ophthalmologist. If the patient cannot see, and their glaucoma isn’t controlled, Swinger recommended a comfort procedure.

Although he noted that it is not directly emergency-related, Swinger included a reminder that primary glaucoma is a bilateral disease. So, when faced with primary glaucoma, it’s essential to start the unaffected eye on prophylactic therapy. Otherwise, the second eye will develop glaucoma as well, “within about 3 months.”

Swinger stressed the importance of starting therapy early for the best results. “With prophylactic therapy we can buy ourselves maybe 2 years before we start to see the problems of glaucoma,” he said.

SwingerR. It’s all fun and games until someone loses an eye: an overview of ophthalmic emergencies. Presented at: American Veterinary Medical Association Convention; Austin, TX: June 20-25, 2024.