Objective: Early detection of glaucoma remains a challenging problem and needs long-term, prospective studies. The pattern electroretinogram (PERG) directly reflects retinal ganglion cell function. The PERG was evaluated by extending a prospective study of patients with ocular hypertension and evaluated amplitude, PERG ratio, peak time, and trends thereof.

Methods: One hundred twenty eyes of 64 patients with intraocular pressure greater than 25 mm Hg (or ≥ 23 mm Hg with additional risk factors), normal visual fields, normal optic disc appearance, and visual acuity ≥ 0.8 were included in the study. Mean follow-up time was 10.3 years. The per-visit measures of amplitude at 15 reversals/s to 0.8° check size, PERG ratio (0.8°/16°), peak time, visual field, and their trends were analyzed.

Results: Over the course of the study 13 eyes converted to glaucoma according to a visual field definition. Amplitude to 0.8° check size, PERG ratio, and peak time were significantly lower in converters. Amplitude and PERG ratio predicted conversion 4 years ahead with a sensitivity/specificity of 67%/64% and 75%/76%, respectively. At this time, the ROC area was already significantly above chance for the PERG ratio. Comparison of the trends of converters and nonconverters revealed significant differences in the PERG ratio; however, trends did not predict conversion as successfully as single-visit measures.

Conclusions: The PERG, especially the PERG ratio, detected glaucoma patients 4 years before visual field changes occurred, with a sensitivity/specificity of 75%/76%. Slope analysis required multiple visits, but provided little additional information in detecting converters.