Ophthalmology: Structure, Pathology and Clinical Reasoning
Core concepts
The Ophthalmology paper rewards a layered understanding: anatomy and physiology (cornea, aqueous outflow, lens, retina, optic nerve), then pathology, then clinical decision-making. Be fluent in the aqueous circulation (ciliary body → posterior chamber → pupil → anterior chamber → trabecular meshwork/Schlemm canal), because it underpins glaucoma questions. Know the layers of the cornea and which dystrophies affect which layer, the difference between open-angle and angle-closure mechanisms, and the classic retinal diagnoses (retinal detachment, vein occlusion, diabetic retinopathy, macular degeneration).
Traps
Questions frequently test the distinction rather than the definition. For example, sudden painless visual loss suggests vascular or retinal causes, whereas painful red eye suggests acute angle-closure, uveitis, or keratitis. Watch for laterality, time course, and pupil findings. A common trap is confusing papilloedema (bilateral, raised ICP) with optic neuritis (usually unilateral, painful on movement, relative afferent pupillary defect).
Worked example
A 65-year-old presents with a painful red eye, halos around lights, a fixed mid-dilated pupil, and a hazy cornea. The combination points to acute angle-closure glaucoma: the mechanism is pupillary block, so the first-line definitive treatment is a peripheral laser iridotomy after lowering intraocular pressure medically. The exam trap is choosing a pressure-lowering drop alone as the answer; the question asks for the definitive intervention.
Rule of thumb
When unsure, ask: Is this a structural, vascular, inflammatory, or pressure problem? The answer narrows the differential and the investigation.