Effect of Cosopt Versus Combigan on Retinal Vascular Autoregulation in Primary Open Angle Glaucoma (POAG)

We have completed a study in which we examined the response of the retinal circulation to
changes in posture from sitting to lying down in patients with primary open angle glaucoma
(POAG). This alteration in position produces changes in the local blood pressure at the
entrance to the retinal vasculature. In a healthy retina, the vasculature adapts by dilating
and constricting in order to maintain a steady blood flow rate. In an eye with POAG, this
often does not occur. As a result, there are large fluctuations in blood flow which may
produce the retinal neuronal damage associated with glaucoma.

The purpose of this study is to demonstrate that topical anti-glaucoma treatments with
agents that have vasoactive as well as IOP-lowering effects can have a beneficial effect on
maintaining a steady retinal blood flow rate even when there are changes in local blood
pressure.