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Abstract #18988 Published in IGR 3-1
Impaired visual function in glaucoma
Parisi VClinical Neurophysiology 2001; 112: 351-358
OBJECTIVE: This work aims to evaluate whether glaucomatous visual field defects could be related to impaired retinal function, delayed neural conduction in postretinal visual pathways, or both. METHODS: Visual field by Humphrey perimeter (central 24-2 threshold test) and simultaneous recordings of visual evoked potential (VEP) and pattern electroretinogram (PERG) were assessed in 21 subjects with open-angle glaucoma (POAG) and in 15 age-matched controls (C). RESULTS: VEP: in POAG eyes, P199 latency was found to be significantly (p < 0.01) delayed when compared with controls and correlated with mean deviation (index of global visual field damage, MD) of 24-2 Humphrey perimetry (p < 0.001); the P100 amplitudes were significantly (p < 0.01) lower in POAG eyes than in control eyes and correlated with MD (p < 0.001). PERG: POAG eyes showed P50 latency significantly (p < 0.01) delayed when compared with controls and correlated with MD (p = 0.002); the P50 and N95 amplitudes were significantly (p < 0.01) lower in POAG than in control eyes and correlated with MD (P50: p = 0.006; N95: p = 0.002). Retinocortical time (RCT: difference between VEP P100 and PERG P50 latencies) and latency window (LW: difference between VEP N75 and PERG P50 latencies) were significantly (p < 0.01) longer in POAG eyes than in control eyes and correlated with MD (RCT: p < 0.001; LW: p < 0.001). No significant correlations (p > 0.05) were found between electrophysiological parameters and the corrected pattern standard deviation (index of localized visual field damage) of 24-2 Humphrey perimetry CONCLUSIONS: In patients with POAG, reduction of the index of global visual field damage (MD) could be ascribed to two sources of functional impairment: one retinal (impaired PERG) and one postretinal (delayed RCT and LW). In the postretinal impairment, a postsynaptic degeneration at the level of the lateral geniculate nucleus could be suggested.
V. Parisi, Cattedra di Clinica Oculistica, Universita' di Roma 'Tor Vergata', Via Santa Maria Goretti 66, 00199 Rome, Italy
Classification:
6.3.2 Posterior segment (Part of: 6 Clinical examination methods > 6.3 Biomicroscopy (slitlamp))
