Ocular perfusion pressure and the incidence of glaucoma: real effect or artifact? The Rotterdam Study.

PURPOSE To determine the association between the ocular perfusion pressure (OPP; essentially the difference between the blood pressure and the intraocular pressure [IOP]) and incident open-angle glaucoma (OAG). METHODS A subset of 3882 participants of the population-based Rotterdam Study for whom data from ophthalmic examinations at baseline and follow-up and blood pressure measurements at baseline were available, and who did not have OAG at baseline, were included. Associations between the mean, systolic and diastolic OPP, and incident OAG were assessed using Cox regression models adjusted for age and sex, with and without adjustment for IOP. RESULTS During a mean follow-up of 9.8 years, 103 participants (2.7%) developed OAG. The association between the mean OPP and incident OAG was not significant (hazard ratio 0.995 per mm Hg increase in mean OPP; 95% confidence interval 0.971-1.019) when adjusted for IOP, but became significant if not adjusted for IOP (0.968; 0.945-0.992). The systolic and diastolic OPP showed a pattern similar to that of the mean OPP, though less significant. CONCLUSIONS The OPP appears to be associated with incident OAG but this association seems to be due to the fact that the IOP, a strong risk factor for OAG, is part of the OPP, rather than that OPP is an independent OAG risk factor itself.