To investigate the changes of pattern electroretinogram (PERG) after intraocul ar pressure lowering in glaucoma patients and normal controls. Interventional re trospective cross-sectional study. Twenty-five patients (49 eyes) with ocular hypertension or glaucoma undergoing topical treatment to lower IOP served as a s tudy group; 22 patients (44 eyes) with ocular hypertension or glaucoma observed without treatment served as a control group for treated glaucoma patients; 9 nor mal subjects (18 eyes) receiving a 250-mg acetazolamide tablet served as a seco nd study group; and 17 normal subjects (34 eyes) from a previous study served as a second control group for treated normal subjects. Pattern electroretinograms were recorded simultaneously from both eyes using skin electrodes and automated analysis. Visual field (VF) analyses were performed with white-on-white standa rd automated perimetry (SAP). Intraocular pressure was measured with Goldmann ap planation tonometry; central corneal thickness was measured with pachymetry. Pat tern electroretinogram amplitude (microvolts), phase (π.rads), and test-retest variability (test 2-to-test 1 ratio, in decibels), SAP mean deviation (decibe ls), and IOP (millimeters of mercury). In 56%of right eyes and 21%of left eyes of the treated glaucoma subgroup, the PERG amplitude and/or phase improved beyo nd 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 impai red VFs showed little improvement in PERG; however, eyes of normal subjects trea ted with acetazolamide did not show significant PERG changes relative to the tes t-retest variability of normal controls. Retinal ganglion cell function can be at least partially restored after IOP reduction in glaucomatous eyes with early VF impairment. To investigate the changes of pattern electroretinogram (PERG) after intraocular pressure lowering in glaucoma patients and normal controls. Interventional re cross-sectional study. Twenty-five patients (49 eyes) with ocular hypertension or glaucoma undergoing topical treatment to lower IOP served as the tudy group; 22 patients (44 eyes) with ocular hypertension or glaucoma observed without treatment served as a control group for treated glaucoma patients; 9 nor mal subjects (18 eyes) receiving a 250-mg acetazolamide tablet served as a seco nd study group; and 17 normal subjects (34 eyes) from a previous study served as a second control group for treated normal subjects. Pattern electroretinograms were recorded simultaneously from both eyes using skin electrodes and automated analysis. -on-white standa rd automated perimetry (SAP). Intraocular pressure was measured with Goldmann ap planation tonometry; central corneal thi Pat tern electroretinogram amplitude (microvolts), phase (π.rads), and test-retest variability (test 2-to-test 1 ratio, in decibels), SAP mean deviation (decibe ls), and IOP In 56% of right eyes and 21% of left eyes of the treated glaucoma subgroup, the PERG amplitude and / or phase improved beyo nd the 95% confidence intervals of the test-retest variability of the untreated glaucoma control eyes with severely impai red VFs showed little improvement in PERG; however, eyes of normal subjects trea ted with acetazolamide did not show significant changes in glaucoma the tes t-retest variability of normal controls. Retinal ganglion cell function can be at least partially restored after IOP reduction in glaucomatous eyes with early VF impairment.