PATTERN ELECTRORETINOGRAM IN TREATED OCULAR HYPERTENSION - A CROSS-SECTIONAL STUDY AFTER TIMOLOL MALEATE THERAPY

To investigate pattern electroretinogram changes in treated ocular hyp ertension, we evaluated pattern electroretinogram recordings of 48 hyp ertensive eyes following an 8-month timolol maleate therapy, During tr eatment, 27 of 48 eyes had normalized intraocular pressures (15-18 mm Hg), while 21 retained elevated values (21-25 mm Hg). Twenty-eight eye s with untreated hypertension (22-25 mm Hg) lasting at least 8 months, as well as 32 untreated, normotensive eyes served as controls. When c ompared to untreated normotensive controls, timolol-treated eyes with either elevated or normalized intraocular pressures showed reductions in the mean electroretinographic amplitudes, However, these amplitude reductions were substantially greater in treated eyes with elevated pr essures as compared to those with normalized ones. Untreated hypertens ive controls showed pattern electroretinogram reductions, with respect to normal values, that were comparable to those of treated hypertensi ve eyes, but larger than those of treated normotensive ones. These res ults indicate that, in treated ocular hypertension, pattern electroret inogram losses tend to be associated with moderately increased intraoc ular pressures in the range of 21-25 mm Hg. Electroretinographic abnor malities may be, at least in part, prevented only by lowering intraocu lar pressure into a normal range.