Effect of sex in branch retinal vein occlusion.

PURPOSE: To evaluate the effect of sex in relation to crossing numbers, arterial overcrossings and occlusion sites in patients with branch retinal vein occlusion (BRVO).

METHODS: Fifty-one eyes with BRVO (study group) and 48 eyes with retinal problems other than BRVO (control group) were investigated. All venous occlusions were examined in detail with regard to their anatomical positions, sites and arteriovenous crossings on the retinal surrounding area two disc diameters nasally, four disc diameters temporally, three disc diameters superiorly and three inferiorly from the optic disc, in the arteriovenous phase of fundus fluorescein angiography and fundus color photography.

RESULTS: The study group comprised 29 women (56.86%) and 22 men (43.14%). All occlusions were unilateral and located at the crossing areas. BRVO had arterial overcrossing in 28 eyes (96.6%) in females and 22 eyes (95.5%) in males (p>0.005). The average numbers of crossings were 7.79 +/- 1.57 in females and 7.82 +/- 1.05 in males in the study group (p>0.05), and respectively 7.30 +/- 1.19 and 6.95 +/- 1.13 (p>0.05) in the control group. The average arterial overcrossing ratios were 75% in females and 71% in males in the study group (p>0.05), and 74% and 65% in the control group (p<0.05).

CONCLUSIONS: Our data suggest that females have a higher risk than males because of their arterial overcrossing ratio and BRVO prefer arterial overcrossing. However the insignificant difference between the female and male patients leads us to assume that the effect of sex on BRVO cannot be explained only by local anatomical factors since their effect is only slight.