If the ocular perfusion pressure is decreased, the risk for ischemic retinopathies such as diabetic retinopathy may increase. What is a surrogate for an increased retinal vein pressure. Persons with higher CSFP may thus have a lower ocular perfusion pressure and potentially due to that mechanism, a higher prevalence of diabetic retinopathy. If the association between higher CSFP and presence and severity of diabetic retinopathy is further clarified in future studies, one may address the question whether lowering of CSFP by drugs such as systemic carbonic anhydrase inhibitors may have a therapeutically positive effect on diabetic retinopathy. Potential limitations of our study should be mentioned. First, the whole study depended on the estimation of CSFP being derived from a multivariate formula incorporating body mass index, diastolic blood pressure, and age. The result of this formula was then termed CSFP and it correlated with the presence and severity of diabetic retinopathy in multivariate analyses. Although the Tubeimoside-I estimated CSFP was primarily just the result of a mathematical equation, the calculated CSFP values correlated well with invasively measured CSFP values in the independent test group of the pilot study. Nonetheless, the unknown general validity of the equation to estimate the CSFP may be the most important limiting factor of our study. Second, some of the components of the formula to estimate the CSFP were by themselves associated with diabetic retinopathy. It has therefore remained unclear whether diabetic retinopathy was correlated with CSFP or with the individual components that were used to calculate CSFP. In the multivariate analysis, the presence of diabetic retinopathy was significantly associated with higher CSFP after adjusting for systolic and diastolic blood pressure, while diabetic retinopathy was not associated with age or body mass index in the model. Since the three parameters of age, blood pressure and body mass index influence CSFP and since body mass index and blood pressure were also associated with diabetic retinopathy in univariate analysis, it was not possible to distinguish between a 14alpha-hydroxy-Sprengerinin-C direct effect of CSFP on the prevalence of diabetic retinopathy and a secondary effect by the underlying basic parameters. Such a question may be addressed in a study comparing patients who have diabetic retinopathy and who have elevated or normal CSFP as measured 
by direct lumbar puncture. Such a design is however not possible to implement in a population-based investigation. Third, as for any population-based study, the rate of nonparticipation or non-availability of examination results can ma er. In our study, the participation rate was 78.8% what may be acceptable. Fourth, blood pressure, although measured under standardized conditions, was determined only once, so that the question arises how representative this single measurement was for the subject��s blood pressure in general. In conclusion, higher prevalence and severity of diabetic retinopathy were associated with higher estimated CSFP after adjusting for systemic parameters. Higher CSFP through a higher central retinal vein pressure may lead to more marked retinal venous congestion and vascular leakage in diabetic retinae.