S Toleikis | PubMed Health

PubMed1991

The effects of age on steady-state pattern electroretinograms and visual evoked potentials.

Steady-state pattern-reversal electroretinograms and visual evoked potentials were simultaneously recorded in two groups of young and elderly normal volunteers. The young group consisted of 23 subjects (13 women and 10 men) aged 18 to 28 years, and the elderly group consisted of 24 subjects (11 women and 13 men) aged 58 to 77 years. Stimuli were square-wave gratings ranging in spatial frequency from 0.5 to 6 c/deg and phase reversed at a frequency of 4 Hz. Pattern-reversal electroretinograms and visual evoked potentials consisted of a prominent second and a smaller fourth harmonic response. Spatial frequency-amplitude functions of the pattern-reversal electroretinogram second and fourth harmonics were similar for the young and elderly groups. The mean fourth harmonic phase was significantly shifted in elderly subjects compared with young subjects for all spatial frequencies tested. Spatial frequency tuning was observed for amplitude and phase functions of the visual evoked potential second and fourth harmonic responses for both age groups. Age had a significant effect on phase for spatial frequencies above 1.5 c/deg. Amplitude of the fourth harmonic was significantly lower for the elderly group at 1.5-4 c/deg. Phase was significantly different between groups for spatial frequencies below 3 c/deg. Our results suggest that aging influences both retinal and central visual pathways. Aging differentially affected the visual evoked potential second and fourth harmonic responses, suggesting different neuronal origins for these components.

Adolescent↗

PubMed1990

Optic neuritis: a prospective study.

We studied 20 patients with acute optic neuritis prospectively for 12 months. Visual fields, color vision, and VEPs to 15' checks were initially abnormal in all patients. Visual acuity was abnormal in 90% and contrast sensitivity in 95% of patients. We devised a graded visual impairment scale (GVIS) to include all visual functions tested. Complete recovery of visual function occurred in 65% of cases. Recovery in the majority of patients was rapid and complete within the first 2 months. In some patients, improvement continued over 6 months. The initial classification on the GVIS was significantly correlated with the final outcome. Patients initially classified as having moderate visual impairment recovered completely or improved to near normal vision. Sixty percent of patients initially classified as total or severe blindness had permanent visual impairment. VEP latency remained prolonged in 19 patients, even when their vision had returned to normal, and is a reliable indicator of resolved optic neuritis.

Adult↗