Ocular rigidity characterizes the relationship between pressure and volume changes in the human eye and is expressed as a macroscopic coefficient. Outflow facility is a measure of the resistance of the conventional outflow pathway and represents a parameter that is of interest in glaucoma.

Difficulties in the measurement of ocular rigidity in the living human eye have limited our knowledge on this parameter. However, ocular biomechanics have been implicated in the pathogenesis of this disease. The aim of this study is to characterize the pressure volume relation and quantify ocular rigidity and outflow facility in glaucomatous and normal eyes. For this purpose, the investigators have recently developed a manometric method for the measurement of ocular rigidity and outflow facility.

Inclusion Criteria:

• Patients with primary open or pseudoexfoliation glaucoma that are undergoing cataract surgery
• Patients undergoing cataract surgery without evidence of other ocular disease.

Exclusion Criteria:

• Evidence of any ocular disease, other than specified in the inclusion criteria
• Previous ophthalmic surgery or trauma
• Significant visual field defect (MD<-12dB) or an increased cup to disc ratio (>0.9).