The impact of intraocular pressure reduction on retinal ganglion cell function measured using pattern electroretinogram in eyes receiving latanoprost 0.005% versus placebo

Abstract

Purpose To evaluate the impact of intraocular (IOP) reduction on retinal ganglion cell (RGC) function measured using pattern electroretinogram optimized for glaucoma (PERGLA) in glaucoma suspect and glaucomatous eyes receiving latanoprost 0.005% versus placebo. Methods This was a prospective, placebo-controlled, double masked, crossover clinical trial. One randomly selected eye of each subject meeting eligibility criteria was enrolled. At each visit, subjects underwent five diurnal measurements between 8:00 am and 4:00 pm consisting of Goldmann IOP, and PERGLA measurements. A baseline examination was performed following a four-week washout period, and repeat examination after randomly receiving latanoprost or placebo for four-weeks. Subjects were then crossed over to receive the alternative therapy for four weeks following a second washout period, and underwent repeat examination. Linear mixed-effect models were used for the analysis. Results Sixty-eight eyes (35 glaucoma, 33 glaucoma suspect) of 68 patients (mean age 67.4 ±10.6 years) were enrolled. The mean IOP (mmHg) after latanoprost 0.005% therapy (14.9±3.8) was significantly lower than baseline (18.8±4.7, p<0.001) or placebo (18.0±4.3), with a mean reduction of −20 ± 13%. Mean PERGLA amplitude (μv) and phase (π-radian) using latanoprost (0.49 ± 0.22 and 1.71 ± 0.22, respectively) were similar (p>0.05) to baseline (0.49±0.24 and 1.69±0.19) and placebo (0.50±0.24 and 1.72±0.23). No significant (p>0.05) diurnal variation in PERGLA amplitude was observed at baseline, or using latanoprost or placebo. Treatment with latanoprost, time of day, and IOP were not significantly (p>0.05) associated with PERGLA amplitude or phase. Conclusion Twenty percent IOP reduction using latanoprost monotherapy is not associated with improvement in RGC function measured with PERGLA.

Effects of acutely lowering intraocular pressure on the results of multifocal visual evoked potential testing

“…A significant amount of eyes revealed improvement on retesting following this IOP reduction, suggesting reversible improvement in retinal ganglion cell function (Ventura & Porciatti 2005). In contrast, a recent study by Sehi and colleagues on patients with glaucoma or glaucoma suspects who received latanoprost 0.005% or placebo for a target of 20% IOP reduction did not find improvement on PERG optimized for glaucoma detection (PERGLA) testing (Sehi et al 2011). However, the same authors found reversal of retinal ganglion cell dysfunction after surgical reduction in IOP which was quantifiable by PER-GLA (Sehi et al 2010).…”

Neurodegeneration in glaucoma: progression and calcium-dependent intracellular mechanisms

“…Interestingly the association between elevated IOP and PERG outcome remains ambiguous. There is evidence of a positive relationship in that lowering IOP improves PERG amplitude (Nagaraju et al, 2007; Porciatti and Nagaraju, 2010), but other studies indicate no relationship between PERG amplitude and IOP elevation (Johnson et al, 1989; Sehi et al, 2010). …”

Evaluation of retinal ganglion cell function after intraocular pressure reduction measured by pattern electroretinogram in patients with primary open-angle glaucoma

“…A clinical trial published in 2011 by Sehi et al [6] tried to evaluate the impact of IOP reduction on RGC function in glaucoma suspect and glaucomatous eyes receiving latanoprost 0.005%, using PERGLA. This prospective trial did not reveal significant changes in PERGLA amplitude after therapy, with either latanoprost or placebo.…”