Pattern ERG as an early glaucoma indicator in ocular hypertension: a long-term, prospective study.

PURPOSE: The conversion rate from untreated ocular hypertension (OHT) to glaucoma is only approximately 1% per year. Discrimination of nonconverters and potential converters would help reserve preventative treatment for those who need it and thus avoid unnecessary side effects and expenditure for those who do not. This prospective study was designed to assess the pattern electroretinogram (PERG) as an early indicator of dysfunction preceding glaucoma.

METHODS

Ninety-five eyes of 54 patients with intraocular pressure > or =25 mm Hg (or > or =23 mm Hg with additional risk factors), normal visual fields, normal optic disc cupping, and visual acuity > or =0.8 were evaluated. Every 6 months during a median follow-up of 8.2 years, the PERG and visual fields were obtained besides other standard diagnostics. PERGs were recorded in steady state mode in response to checkerboard stimuli at 15 reversals/s, and the amplitudes in response to check sizes of 0.8 degrees and 16 degrees as well as the ratio of the amplitude of responses to 0.8 degrees over that to 16 degrees checks were determined.

RESULTS

Glaucomatous visual field defects developed in eight eyes. For the PERG to 0.8 degrees checks and for the PERG ratio, analysis of the receiver-operating characteristic (ROC) yielded steadily increasing ROC areas before conversion (i.e., an increasing ability of the PERG to predict nonconversion or conversion). One year before conversion, the ROC area of the PERG ratio was 0.78; at a threshold of 1.06 this corresponded to a sensitivity of 80% and a specificity of 71%.

CONCLUSIONS

The PERG can help to predict stability or progression to glaucoma in OHT at least 1 year ahead of conversion.