Ocular Disease Diagnosis and Management
This domain tests pattern recognition and triage: which findings mandate same-day referral, and which can be monitored.
Frameworks
- Glaucoma: IOP is a risk factor, not a diagnosis. Assess disc (cup-to-disc ratio, rim thinning, RNFL), visual field, and gonioscopy; document progression with imaging.
- Diabetic retinopathy: grade NPDR (mild, moderate, severe) versus PDR (NVD, NVE, vitreous haemorrhage); centre-involving DME needs anti-VEGF, not just observation.
- AMD: dry with drusen or geographic atrophy; wet with choroidal neovascularisation causing metamorphopsia and rapid loss - urgent anti-VEGF.
- Keratoconus: inferior steepening, asymmetric topography, rising K-max; corneal cross-linking for documented progression.
- Dry eye: tear break-up time, osmolarity, MMP-9; stepwise management from lubricants to anti-inflammatory therapy.
Red flags
Sudden painless loss of vision (retinal artery occlusion), painful red eye with a fixed mid-dilated pupil (acute angle closure), flashes and floaters with field loss (retinal detachment), and jaw claudication with visual symptoms in an older patient (giant cell arteritis).
Worked example
A nasal step with inferotemporal rim thinning and a cup-to-disc ratio of 0.7 in one eye. Reasoning: the field defect respects the horizontal midline and corresponds to the damaged disc sector, so it is glaucomatous rather than neurological. Neurological defects typically respect the vertical midline and are homonymous.
Traps
Treating the IOP number rather than the disc and field; omitting gonioscopy so a narrow angle is missed; labelling all cupping as glaucomatous when physiological cupping is asymmetric but stable; and observing centre-involving DME.