Does type II diabetes predispose to retinal vein occlusion?

Retinal vein occlusion (RVO) not infrequently occurs in diabetic patients. Although the aetiology is unclear, it could relate to the other microvascular complications of diabetes. In the non-diabetic, both the central (CRVO) and branch (BRVO) forms are commonly associated with hypertension and hyperlipidaemia. We have therefore studied fifty type II diabetic patients with RVO compared to a carefully matched diabetic control group (n = 50) to elucidate underlying medical conditions and hence the aetiology of RVO in diabetic patients. The two groups were well matched. Diabetics with RVO showed a strikingly high prevalence of hypertension compared to the controls (72% versus 32%: p < 0.001) and a trend to increased hyperlipidaemia (54% versus 36%). Diabetic microvascular complications were more common in the control group (diabetic retinopathy and proteinuria). No significant differences were observed in mean HbA1 or weight, but current smoking habits and blood pressure levels were increased in the diabetics with RVO. 80% of diabetic patients with the BRVO form, were hypertensive. We conclude that the main underlying medical conditions for RVO in diabetics are hypertension and hyperlipidaemia, and these may be important in the aetiology as in the non-diabetic. RVO is more common in type II rather than type I diabetes, and does not associate with the presence of diabetic microvascular complications. Clinical assessment for hypertension and hyperlipidaemia is therefore important in diabetic patients with RVO, especially if recurrence of the condition and further visual loss is to be prevented.