Underlying medical conditions in young patients and ethnic differences in retinal vein occlusion.

Eighty-seven patients with retinal vein occlusion were investigated for the prevalence of associated conditions, and divided in two groups, young (less than 50 years, n = 40) and an older group (greater than 50 years, n = 47). Young patients had a highly significant decreased prevalence of hypertension compared to the older group (27 per cent versus 62 per cent: P less than 0.001), with hyperlipidaemia being the predominant underlying condition (35 per cent). Four young female patients presenting with retinal vein occlusion were on the contraceptive pill. In the majority of young patients (60 per cent) an underlying medical condition could be identified. Striking ethnic differences in the occurrence of retinal vein occlusion have also been observed in a total of 214 patients referred without prior selection in two major ophthalmological centres over a four year period. Only 3 per cent of patients with retinal vein occlusion were Asian and 2 per cent of West Indian origin. In particular, no West Indian patient has been seen with the central form of venous occlusion. We conclude that hyperlipidaemia, and not hypertension, is the predominant associated medical condition in young patients and that other aetiological factors including the contraceptive pill may be found. Marked ethnic differences have also been observed which may give further insight into the exact aetiology of retinal vein occlusion.