Intraocular Pressure: Does it Measure Up?

The relationship between intraocular pressure (IOP) and glaucoma is complex and not fully understood. We question the validity of several claims relating to the IOP-glaucoma relationship: (1) that 12 mm Hg is an important target in IOP control; (2) that IOP variability is an important risk factor for glaucoma progression; and (3) that every millimeter of mercury of IOP lowering reduces the risk of glaucoma progression by some specific percentage amount. Further, IOP is generally accepted to be an important – if not most important – risk factor for glaucoma development and progression. Using measures of treatment effect – absolute risk reduction, relative risk, and relative risk reduction – we compare the strength of IOP as a risk factor to the strength of a cardiac risk factor in cardiovascular disease.