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Evoked potential analysis of visual pathways in human albinism
E A Bouzas1, R C Caruso, M A Drews-Bankiewicz
1Ophthalmic Genetics and Clinical Services Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892.
Ophthalmology
|February 1, 1994
Summary
Visual-evoked potentials (VEPs) reveal abnormal visual pathway crossing in albinism. Most patients showed asymmetric scalp responses, indicating widespread miswiring in the retinogeniculate pathways.
Area of Science:
- Neuroscience
- Ophthalmology
- Genetics
Background:
- Albinism is a genetic disorder characterized by reduced pigmentation.
- Abnormal crossing of visual pathways is a known feature in albinism.
- Visual-evoked potentials (VEPs) are used to assess the integrity of the visual pathway.
Purpose of the Study:
- To investigate the abnormal crossing of retinogeniculate pathways in human albinos.
- To analyze the topographic distribution of pattern onset/offset VEPs in patients with albinism.
Main Methods:
- Monocular stimulation of each eye in 31 patients with various types of albinism.
- Recording pattern onset/offset VEPs over the posterior scalp.
- Assessing the symmetry of VEP topographic distribution.
Main Results:
- Twenty-one patients exhibited asymmetric VEP responses.
- Major amplitudes were recorded contralaterally (14 patients) or ipsilaterally (7 patients) to the stimulated eye.
- Two patients showed symmetric responses, and eight had VEPs too low to assess symmetry.
Conclusions:
- Findings demonstrate a non-uniform pattern of asymmetry in the visual pathways of human albinos.
- Miswiring of the retinogeniculate pathways is evident in albinism.
- Low VEP amplitudes present challenges for clinical study of this phenomenon.