Risk Factors of Branch Retinal Vein Occlusion
Abstract
Abstract To the Editor. —In their case-control study, "Risk Factors of Branch Vein Occlusion," Johnston et al, in the December 1985 issue of the Archives,1 state that systemic hypertension is a risk factor, with 60% of cases studied being hypertensive as compared with 47% of controls (P =.011). The answer to the several important methodological questions that follow would be helpful in assessing their claim: (1) Was hypertension determined comparably in the retrospective cases...