Glaucoma and Optic Nerve Disease
Glaucoma items test the difference between an intraocular pressure reading and the disease itself, plus your ability to grade the optic nerve and field.
Core rules
IOP is a risk factor, not a diagnosis; a single normal pressure does not exclude glaucoma and a single high reading does not confirm it. Gonioscopy is mandatory to separate open-angle from angle-closure disease. Assess the disc for cup-to-disc ratio, rim thinning (inferior and superior vulnerability), disc hemorrhage, and retinal nerve fiber layer loss on OCT. Fields show nasal steps, arcuate scotomas, paracentral defects, and altitudinal loss that respect the horizontal midline; neurologic fields respect the vertical midline. Progression is confirmed by trend analysis, not a single field.
Risk and treatment
Risk rises with age, higher IOP, thin central cornea, Black ancestry, family history, pseudoexfoliation, and steroid response. Ocular hypertension is treated when calculated risk of conversion is meaningful. First-line therapy is usually a prostaglandin analog at bedtime, targeting a 20 to 30 percent IOP reduction; alternatives are beta blockers, alpha agonists, carbonic anhydrase inhibitors, laser trabeculoplasty, and surgery. Acute angle closure presents with halos, severe pain, nausea, a mid-dilated fixed pupil, corneal edema, and a shallow chamber: lower IOP medically and perform laser peripheral iridotomy.
Worked example
A 60-year-old has IOP 28 in both eyes, a 0.7 cup with inferior rim thinning and a disc hemorrhage, an open angle on gonioscopy, and a superior nasal step. Reasoning: primary open-angle glaucoma with structural and functional loss. Start latanoprost nightly, set a target of about 20 percent reduction, recheck in four to six weeks, and consider selective laser trabeculoplasty as initial or adjunct therapy.
Traps
Skipping gonioscopy; treating an IOP number instead of the optic nerve; missing steroid-induced pressure rise; and calling cataract-related field constriction glaucoma.