Diabetic retinopathy
Chronic hyperglycaemia damages retinal capillaries, driving a progression from microvascular leakage to ischaemia to pathological new vessel growth, which is why screening and staging by the underlying vascular damage, not symptoms, determines when to treat.
First principles
The disease is chronic microvascular damage to retinal capillaries
Sustained hyperglycaemia glycates proteins in the walls of retinal capillaries and damages pericytes, the cells that support and regulate these small vessels. Weakened capillary walls develop microaneurysms and become leaky, allowing blood (haemorrhages) and lipid- or protein-rich fluid (hard exudates) to leak into the retina. Because this damage accumulates silently over years and the peripheral retina causes no symptoms even when damaged, early diabetic retinopathy is asymptomatic, which is exactly why screening, not waiting for symptoms, is the basis of management.
Educational content pending clinical review. Not medical advice.