Glaucoma
This section covers glaucoma: intraocular pressure, gonioscopy, optic nerve assessment, visual fields, medical therapy, laser, and surgery. The exam tests diagnosis and safe acute management.
Core rules and concepts
- Primary open-angle glaucoma is a progressive optic neuropathy with open angles, characteristic disc damage, and field loss; IOP is a major modifiable risk factor but not the diagnosis.
- Gonioscopy is mandatory in every glaucoma work-up to separate open-angle from angle-closure disease.
- Disc signs include increased cup-to-disc ratio, neuroretinal rim thinning, disc haemorrhage, and retinal nerve fibre layer loss on OCT.
- Topical prostaglandin analogues lower IOP most and are first-line in many open-angle cases; beta-blockers are avoided in asthma and heart block.
- Acute angle closure is an emergency: lower IOP medically, then perform laser peripheral iridotomy.
Worked example
A 62-year-old presents with severe headache, nausea, blurred vision, a mid-dilated fixed pupil, corneal haze, and IOP 48 mmHg. The anterior chamber is shallow and gonioscopy shows a closed angle. Treat immediately with topical beta-blocker, alpha-agonist, systemic acetazolamide, and hyperosmotic agents. Pilocarpine may be ineffective while the iris is ischaemic and is added after IOP falls. Definitive treatment is laser peripheral iridotomy to relieve pupillary block, with prophylaxis to the fellow eye.
Traps that cost marks
Never diagnose open-angle glaucoma without gonioscopy. A steroid response can raise IOP dramatically; ask about drops. Normal-tension glaucoma still needs disc and field documentation. Do not delay referral for acute angle closure while waiting for routine tests.