Reversal of Retinal Ganglion Cell Dysfunction after Surgical Reduction of Intraocular Pressure

Purpose: The pattern electroretinogram optimized for glaucoma screening (PERGLA) is a noninvasive method of objectively measuring retinal ganglion cell (RGC) function. This study was undertaken to quantify the RGC response to intraocular pressure (IOP) reduction after glaucoma surgery. Design: Prospective cohort study. Participants: Forty-seven eyes of 47 patients with uncontrolled IOP or progressive glaucomatous optic neuropathy receiving maximal medical therapy requiring trabeculectomy or aqueous drainage device implantation who met eligibility criteria. Methods: Eyes with visual acuity less than 20/30, corneal or retinal pathologic features, or unreliable standard automated perimetry (SAP) results were excluded. All patients underwent complete ocular examination, arterial blood pressure, SAP, and PERGLA at 2 sessions before surgery and at 3 months after surgery. Mean ocular perfusion pressure (MOPP) was calculated. Each measure of PERGLA amplitude and phase was an average of 600 artifact-free signal registrations. Main Outcome Measures: Intraocular pressure and PERGLA amplitude and phase. Results: Forty-seven eyes of 47 patients (mean age +/- standard deviation [SD], 69.9 +/- 11.3 years) were enrolled. Thirty-four eyes (72%) underwent trabeculectomy with antifibrosis therapy; 13 eyes (28%) underwent glaucoma drainage implant surgery. Mean +/- SD postoperative IOP (10.4 +/- 4.6 mmHg) was significantly (P<0.001) reduced compared with that before surgery (19.7 +/- 8.6 mmHg). Mean +/- SD postoperative PERGLA amplitude (0.46 +/- 0.22 mu V) was significantly (P = 0.001) increased compared with preoperative PERGLA amplitude (0.37 +/- 0.18 mu V). Mean +/- SD postoperative PERGLA phase (1.72 +/- 0.20 pi-radian) was significantly (P = 0.01) reduced compared with preoperative PERGLA phase (1.81 +/- 0.22 pi-radian). Mean +/- SD postoperative MOPP (53.1 +/- 6.4 mmHg) was significantly (P = 0.001) increased compared with mean +/- SD preoperative MOPP (45.8 +/- 10.1 mmHg). No correlation (P>0.05) was identified between change in PERGLA amplitude and change in IOP or MOPP. Conclusions: Reversal of RGC dysfunction occurs after surgical reduction of IOP and may be quantified using PERGLA.