Pattern ERG changes in suspected glaucoma.

Pattern ERG (P-ERG) changes were studied in patients with suspected glaucoma. P-ERG was recorded in 48 eyes with good visual acuity, normal visual fields and elevated intraocular pressure ranging between 18 and 26 mm Hg. The amplitude of the P1 wave was within normal limits and ranged between 1.0 and 1.9 microV in 46 eyes (95.8%). In contrast, the amplitude of the N2 wave in 32 eyes (66.6%) was subnormal, ranging between 0.2 and 0.8 microV. The implicit time of the P1 and N2 waves was normal, ranging from 60.1 to 69.4 and from 95.1 to 103.8 ms, respectively. In conclusion, the N2 wave changes of the P-ERG may predict those hypertonic eyes which will eventually develop glaucoma and need early antiglaucoma therapy. On the contrary, in ocular hypertensives with normal N2 wave the development of glaucoma is less likely.