Intraocular pressure fluctuations: how much do they matter?

To review the current literature with regard to the importance of IOP fluctuation/variation as independent risk factors for glaucoma progression.

There are conflicting reports in the literature assessing the relative importance of 'intraocular pressure (IOP) fluctuation' and 'mean IOP' as risk factors for glaucoma progression. There has been a trend toward more studies concluding that IOP fluctuation is an important independent risk factor for such progression but there is considerable variability in the quality of such studies. In particular, assumptions regarding causality have created doubt regarding some conclusions. Recent studies have also suggested that we should not abandon mean IOP as the important predictor of glaucoma progression. It should be noted that several analyses pertaining to this subject have emerged from large prospective randomized clinical trials primarily designed to answer other questions.

A review of the literature reveals that there is no conclusive evidence that IOP fluctuation/variation are independent risk factors for glaucoma progression. One should not discount the importance of mean IOP as a predictor of such progression. A major factor limiting all analyses pertaining to this issue is the inability to continuously measure IOP and thus optimally assess mean and variability.