The visual evoked potentials and the spatial vision in old people.
The latency of the visual evoked potentials elicited by pattern-reversal and onset-offset stimulation was measured in 75 healthy subjects aged 21 to 80 years. In 24 of these subjects the contrast sensitivity threshold was recorded by electrofunctional method. There is a close correlation between increasing latency of visual evoked potentials and age increase. This finding is of greater importance after 60 years. The delayed latencies are obtained with both pattern-reversal and onset-offset stimulation, and are more striking using stimuli of small size. In the old people the contrast sensitivity shows a raised threshold, especially for small stimuli. These age-related changes of the visual evoked potentials and contrast sensitivity are due to optical factors--the most important is the reduction of the retinal illuminance caused by senile miosis--and to neural factors as degeneration and demyelination of the optic nerve axons and abnormalities of the neurotransmitters.
Ponte
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F
Università di Palermo, Istituto di Clinica Oculistica, Italy.
Giuffre
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G
D000328:Adult; D000368:Aged; D015350:Contrast Sensitivity; D004596:Electroretinography; D005074:Evoked Potentials, Visual; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010364:Pattern Recognition, Visual; D013037:Spatial Behavior; D014792:Visual Acuity