Ocular Disease and Pathology: Recognition, Red Flags, and Referral
Core concepts
Candidates must be able to distinguish structural disease of the anterior segment (blepharitis, chalazion, pterygium, corneal ulcer, keratoconus, iritis) from posterior segment disease (cataract, vitreous detachment, retinal tear, diabetic retinopathy, macular degeneration, choroidal nevus versus melanoma). Know the classic sign clusters: a painful red eye with photophobia and consensual light pain suggests anterior uveitis; a painless progressive loss of central vision with drusen suggests macular degeneration; flashes, floaters, and a curtain-like field loss suggest retinal detachment. Understand which findings are urgent (hypopyon, corneal infiltrate, sudden painless vision loss, new field defect, melanotic iris lesion) versus routine.
Traps
Questions often swap "painless" and "painful," or ask which condition is bilateral. Remember that anterior uveitis is typically unilateral and painful, while open-angle glaucoma is painless. Distinguish pinguecula (conjunctival, not crossing the limbus) from pterygium (crosses onto cornea). Do not confuse arcus senilis (benign, corneal periphery) with a limbal ring of Kayser-Fleischer pigment. A white pupil (leukocoria) in a child is retinoblastoma until proven otherwise.
Worked rule of thumb
Use the "three-question triage": Is it painful? Is vision affected? Is it unilateral? A painful, unilateral red eye with reduced vision and photophobia points to uveitis or keratitis and warrants same-day referral; a painless, unilateral field loss points to retinal or neuro-ophthalmic causes and also warrants urgent referral.