Neural conduction in the visual pathways in ocular hypertension and glaucoma

Background: The aim of our work was to evaluate neural conduction in visual pathways in subjects with ocular hypertension and glaucoma. Methods: We assessed simultaneous recordings of pattern electroretinograms (PERG) and visual evoked potentials (VEP) in 16 subjects with ocular hypertension (OHT), in 16 subjects with primary open-angle glaucoma (POAG) and in 15 age-matched controls. The visual stimuli were checkerboard patterns (the check edges subtend 15 min of visual are; contrast 70%) reversed at the rate of 2 reversals/s. Results: In OHT and POAG patients we found PERG and VEP latencies significantly longer than in controls. The P50-N95 PERG amplitudes were significantly reduced in OHT and POAG eyes. VEP amplitudes were significantly reduced in POAG eyes, while in OHT they were similar to controls. The retinocortical time (RCT; difference between VEP P100 latency and PERG P50 latency) was longer in POAG patients than in controls; no differences between patients with OHT and controls were observed. Moreover, we observed that in POAG the longer RCT was inversely related to the PERG amplitude. Conclusion: Our results suggest that involvement of the innermost retinal layers in POAG is accompanied by slowed neural conduction in the visual pathways.