Glaucomatous optic neuropathy and oscillatory potentials in the ERG to long‐duration stimuli

Abstract

Abstract Purpose To mark out OPs in the long‐duration flash ERG in primary open angle glaucoma (POAG) and to determine their role in diagnosis and monitoring of glaucomatous optic neuropathy (GON). Methods 20 healthy subjects and 45 patients with different stages of glaucoma were investigated. Standard OPs and ERG to long‐duration stimuli (200 ms) were recorded. OPs for ON and OFF ERGs were isolated after mathematic filtration (80‐200 Hz). Optic discs of patients were evaluated by confocal scanning laser ophthalmoscopy HRT II. Index (mean) of early and late standard OPs were calculated separately. Results Marked oscillations were determined in both ON and OFF ERG to long‐duration stimuli (3‐4 and 2‐3 waves respectively). Different decrease of amplitudes were detected depending on the stage of POAG. Subnormal OFF‐response of ERG to long‐duration stimulus and late standard OPs were observed in all stages of POAG. ON‐response of ERG to long‐duration stimulus and early standard OPs in the early stage of POAG were supernormal, whereas in the advanced and late stages they were subnormal. A statistically significant correlation was observed between standard OPs and OPs in the ERG to long‐duration stimuli. Conclusion In POAG the OFF cone channels damage earlier. OPs of ERG to long‐duration stimulus are more sensitive indicator of ischemic processes in the retina. A strict correlation between different components of ERG may suppose that early waves of standard OPs are generated by ON‐components of cone and rod pathways, wile the origin of OFF‐OPs is related to OFF‐components of cone pathway.