The overall goal for all glaucoma treatment is to preserve useful vision. Thus, the two most important tasks for the ophthalmologists are to determine the rate of progression in each case and, if necessary, to slow it down sufficiently to reach the overall goal. It may not be possible to arrest progression completely since elderly patients with moderate visual field loss probably have lost most or all of their “reserves” owing to a combination of glaucomatous damage and natural loss of ganglion cells. In such eyes even the continuous natural loss of ganglion cells may manifest itself as a slow progression of the visual field defect, but hardly at a sight threatening rate.

How should this goal be achieved? Although it is generally accepted that open angle glaucoma is a multifactorial disease the intraocular pressure (IOP) is still the only known treatable risk factor. Several studies have shown that the IOP is a graded risk factor where the risk of diagnosing a damaged optic nerve increases with the level of the IOP, even within the normal range of IOP.1 ,2 …