Although it is well recognized that phacoemulsification may result in a modest sustained reduction in IOP, there are several limitations in the studies that have assessed the magnitude of this effect. The implications of such IOP reduction with cataract surgery on the medical and surgical algorithms for care in patients with open-angle glaucoma and coexistent cataract remain unclear. In contrast, the substantial benefits of cataract surgery in patients with acute and chronic angle-closure glaucoma have been well studied and are generally widely accepted. An improved understanding of the pathophysiological mechanisms of IOP lowering after cataract extraction may help us better predict which patients are most likely to benefit from simple cataract extraction, obviating the need for combined cataract and glaucoma surgical procedures in such circumstances.

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.