Relationship Between Eye Pressure and Ganglion Cell Function in Eyes Receiving Latanoprost Versus Placebo

It has been hypothesized that intraocular (IOP) variability is an independent risk factor for the progression of glaucoma. IOP variability includes 24 hour IOP fluctuation during the waking period (diurnal fluctuation) and sleep period (nocturnal fluctuation) as well as longitudinal IOP variability measured in the diurnal period over the course of multiple office visits. Latanoprost has been clinically used to lower eye pressure in glaucoma and ocular hypertension for almost 10 years. Latanoprost 0.005% has been demonstrated to provide superior ocular hypotensive efficacy compared with timolol 0.5% in pivotal phase 3 clinical trials (Alm et al. 1995; Camras 1996). The Pattern Electroretinogram (PERG) is a non-invasive technology that objectively measures the retinal ganglion cell (RGC) function (Porciatti and Ventura 2004). A recent study has demonstrated that the RGC function can be improved following IOP reduction in glaucomatous eyes with early visual field defects (Ventura and Porciatti 2005). The purpose of this investigation is to evaluate the relationship between IOP fluctuation, RGC dysfunction, and optic nerve and retinal nerve fiber layer (RNFL) thickness changes in patients with glaucoma and ocular hypertension receiving latanoprost 0.005% versus placebo.