Ophthalmology/Eye Institute

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Differential Diagnosis:
This patient has the typical presentation for primary open-angle glaucoma (POAG). The diagnosis is confirmed by increased intraocular pressure (IOP), cup-to-disc changes, and visual field deficits. Differential diagnosis would include ocular hypertension, secondary glaucoma, steroid-related glaucoma, pigmentary glaucoma, intermittent angle-closure glaucoma and optic neuropathy.

Definition:
Glaucoma is an optic neuropathy associated with high IOP and a characteristic visual field loss. The primary problem with open-angle glaucoma is a defect in the trabecular meshwork. The normal draining process of the aqueous humor therefore is disrupted, which causes a rise in intraocular pressure (IOP). Months or years later, the increased pressure leads to a thinned, damaged optic disc. This results in vision loss initially in the periphery. Patients may not notice this change for years, as their central vision remains intact.

Examination:
Patients are usually diagnosed during a routine eye exam. Ophthalmologists and optometrists measure intraocular pressure or notice an increased cup-to-disc ratio (greater than 0.2) on funduscopic exam. Examination of the anterior chamber is normal and the past ocular history is otherwise negative. A visual field examination shows field defects peripherally. Risk factors for open angle glaucoma include high intraocular pressure, central corneal thickness (risk is increased the thinner the cornea), race, age and family history (10x the risk in siblings of patients with POAG).

Treatment:
Most eye care providers use medications as first-line therapy, including prostaglandins, adrenergics agonists, beta blockers, and carbonic anhydrase inhibitors. The target is a 30% reduction of the baseline intraocular pressure (ideally an IOP of less than 21 mmHg). Other options for treatment include argon laser trabeculoplasty, trabeculectomy or a tube shunt procedure. The purpose of these treatments is to increase aqueous outflow from the anterior chamber, lowering the intraocular pressure. Regular follow-up is important to include IOP check, visual field assessment and optic nerve examination.
 

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