Retina and Vitreous
Core concepts
Understand retinal vascular anatomy and the blood-retinal barrier. Know diabetic retinopathy staging (NPDR vs PDR) and the role of VEGF. Learn the classification of retinal detachment: rhegmatogenous, tractional, exudative, and their management. Recognize macular degeneration (dry vs wet) and the significance of choroidal neovascularization. Understand retinal vascular occlusions (CRVO, BRVO) and their systemic associations. Know the inherited retinal dystrophies and the classic appearance of retinitis pigmentosa (bone spicules, waxy pallor, vessel attenuation).
Traps
Distinguish a retinal tear from a detachment; flashes and floaters alone may need only dilated exam, but a symptomatic tear with subretinal fluid needs treatment. In CRVO, do not mistake the "blood and thunder" fundus for diabetic retinopathy. Remember that anti-VEGF is first-line for center-involving diabetic macular edema and wet AMD. Do not confuse macular hole (needs vitrectomy) with epiretinal membrane.
Rule of thumb
Any sudden painless vision loss with a visible retinal abnormality should prompt a dilated fundus exam; a pale retina with a cherry-red spot suggests CRAO, while a swollen hyperemic disc with hemorrhages suggests CRVO.
Worked example
A patient with long-standing diabetes presents with sudden painless vision loss and a fundus showing extensive flame hemorrhages and cotton-wool spots in all quadrants. This is CRVO; check for hypertension and cardiovascular risk, and consider anti-VEGF if macular edema is present.