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OHTS: Do not lower IOP merely to prevent vein occlusion
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SAN DIEGO – A presenter here at Optometry’s Meeting said that while glaucoma and vein occlusion are comorbid conditions, lowering IOP only to prevent vein occlusion is unjustified, according to the results of the Ocular Hypertension Treatment Study.
Joseph Sowka, OD, who was part of a panel discussion on glaucoma, told attendees that some property of the blood and central retinal vein act in concert to cause thrombotic occlusion. He said the laminar constriction site is the nidus for occlusion. Intraluminal pressure of the vein decreases, rendering it susceptible to collapse.
Glaucoma and vascular occlusive disease both occur in an older population, he said.
“They often have coexisting vascular disease, such as diabetes, hypertension, hyperlipidemia, atherosclerosis, history of smoking and arteriosclerosis,” Sowka said. “These patients are older and vascularly challenged.”
Sowka asked the audience: “Does glaucoma predispose a patient to vascular occlusion, or does vascular occlusion predispose the patient to glaucoma?”
He took the line of questioning further: “Vascular occlusion can predispose the patient to neovascular glaucoma. But does it predispose the patient to primary open angle glaucoma? Or are they just occurring concurrently in a population with the same risk factors?”
The OHTS study involved 1,636 ocular hypertensive patients with 10-year follow-up, and 26 vein occlusions were seen in 23 participants, Sowka said. Fifteen were in the treatment group and eight were in the observation group.
“That’s not a lot of patients,” he said. “The incidence of vascular occlusion was 2.1% in the untreated group and 1.4% in the medication group.”
OHTS concluded that lowering IOP to prevent vein occlusion is unjustified, Sowka said.
Panel member Richard Madonna, OD, commented, “The threshold for treating an ocular hypertensive goes down depending on the number of risk factors they have.”
“I flip it the other way,” added panel member, Murray Fingeret, OD. “I rarely will treat someone simply based upon eye pressure. If I’m going to treat their high IOP it’s because I’m concerned about them developing glaucoma. But the other side is if someone presents with a vein occlusion in one eye and now they have a pressure of 26 mm Hg or 27 mm Hg in the other eye, I’ll treat.”