Ocular Disease and Systemic Conditions
This domain tests recognition, grading, and appropriate urgency across ocular disease and its systemic associations, including medication-induced ocular effects.
Diabetic eye disease
Non-proliferative diabetic retinopathy is graded by lesion burden. Severe NPDR follows the 4-2-1 rule: haemorrhages in all four quadrants, venous beading in at least two, or intraretinal microvascular abnormalities in at least one. Proliferative disease shows neovascularization of the disc or elsewhere. Diabetic macular oedema is a clinical thickening confirmed with optical coherence tomography, not merely hard exudates near the macula.
Glaucoma and the optic nerve
Open-angle glaucoma is a progressive optic neuropathy; pressure is a risk factor, not the definition. Angle closure presents with pain, haloes, mid-dilated pupil, and corneal oedema and requires urgent pressure lowering and referral.
Systemic and drug associations
- Hydroxychloroquine: risk relates to dose per real body weight, duration, and renal status; monitor with visual fields and macular imaging.
- Topiramate can cause acute secondary angle closure; amiodarone causes vortex keratopathy; ethambutol can cause optic neuropathy.
- Tamsulosin is associated with intraoperative floppy iris syndrome; document it before cataract surgery.
Worked example
A patient with 15 years of type 2 diabetes has haemorrhages in four quadrants, venous beading in two quadrants, and no neovascularization. Reasoning: this meets the 4-2-1 rule for severe NPDR. The correct plan is prompt retinal referral for consideration of panretinal photocoagulation, not routine annual review.
Traps that cost marks
Confusing exudates with oedema; missing neovascularization at the disc margin; attributing a red eye to conjunctivitis when the pupil is mid-dilated and the cornea hazy.