PURPOSE: To investigate the changes of pattern electroretinogram (PERG) after intraocular pressure lowering in glaucoma patients and normal controls. DESIGN: Interventional retrospective cross-sectional study. PARTICIPANTS: Twenty-five patients (49 eyes) with ocular hypertension or glaucoma undergoing topical treatment to lower IOP served as a study group; 22 patients (44 eyes) with ocular hypertension or glaucoma observed without treatment served as a control group for treated glaucoma patients; 9 normal subjects (18 eyes) receiving a 250-mg acetazolamide tablet served as a second study group; and 17 normal subjects (34 eyes) from a previous study served as a second control group for treated normal subjects. METHOD: Pattern electroretinograms were recorded simultaneously from both eyes using skin electrodes and automated analysis. Visual field (VF) analyses were performed with white-on-white standard automated perimetry (SAP). Intraocular pressure was measured with Goldmann applanation tonometry; central corneal thickness was measured with pachymetry. MAIN OUTCOME MEASURES: Pattern electroretinogram amplitude (microvolts), phase (pi rads), and test-retest variability (test 2-to-test 1 ratio, in decibels), SAP mean deviation (decibels), and IOP (millimeters of mercury). RESULTS: In 56% of right eyes and 21% of left eyes of the treated glaucoma subgroup, the PERG amplitude and/or phase improved beyond the 95% confidence intervals of the test-retest variability of the untreated glaucoma control group. Pattern electroretinogram improvement with IOP lowering occurred in both high- and low-tension glaucoma eyes. Eyes with severely impaired VFs showed little improvement in PERG; however, eyes of normal subjects treated with acetazolamide did not show significant PERG changes relative to the test-retest variability of normal controls. CONCLUSIONS: Retinal ganglion cell function can be at least partially restored after IOP reduction in glaucomatous eyes with early VF impairment.
Dr. L.M. Ventura, Bascom Palmer Eye Institute, Miami, Florida 33136, USA