Journal francais d'ophtalmologie · 2000
[Exploration of retro-chiasmatic visual pathways in human albinism].
Аннотация на английскомСтатьяНазвание и аннотация: Перевод пока не подготовлен
Обработка статьи · этапы, ошибки и управление
Загрузка состояния…
Ошибки и ограничения
История · было → стало
Состояние обновляется каждые 5 секунд, пока блок открыт. Процент показывается только там, где известен объём работы. Пауза останавливает продолжение этапа; текущий запрос к источнику может завершиться.
Jarry D, Roussat B, Rigolet M H, Hamard H
Аннотация
PURPOSE: Several research studies have explored the abnormal crossing of the retinogeniculate and geniculocortical optic pathways in human albinos. This prospective study has dealt with visual evoked potentials (VEPs) of human subjects to identify the percentage of albinos with asymmetric VEPs.
PATIENTS AND METHODS: A series of 16 albino patients ranging in age from 6 to 37 years were examined. They had measurable visual acuity, with or without nystagmus. Diffusion of flash stimuli not allowing selective study of the two visual pathways (direct and crossed), two stimulation patterns were used for VEP recordings: monocular full open field then hemi-field stimulation to isolate the activity of each visual pathway.
ANALYSIS: In the normally pigmented subject, fibers derived from the nasal half of the retina of each eye decussate at the chiasma, while temporal retinal fibers are uncrossed and project to the ipsilateral hemisphere. In albinos, the majority of temporal retinal fibers subserving the nasal field (from fixation to an eccentricity of about 20 degrees ) anomalously cross with the nasal retinal fibers. Therefore with monocular stimulation, the evoked visual response should be obtained only in the contralateral hemisphere. The asymmetry, morphology and latency for the first major positive peak and the amplitude of the VEP were examined and compared with the normal population.
CONCLUSION: We managed to demonstrate the characteristic VEP asymmetry only in 3 out of the 16 patients. The results presented herein lead to question the absolute validity of VEP abnormality in diagnosis of albinism for clinical purposes.
PATIENTS AND METHODS: A series of 16 albino patients ranging in age from 6 to 37 years were examined. They had measurable visual acuity, with or without nystagmus. Diffusion of flash stimuli not allowing selective study of the two visual pathways (direct and crossed), two stimulation patterns were used for VEP recordings: monocular full open field then hemi-field stimulation to isolate the activity of each visual pathway.
ANALYSIS: In the normally pigmented subject, fibers derived from the nasal half of the retina of each eye decussate at the chiasma, while temporal retinal fibers are uncrossed and project to the ipsilateral hemisphere. In albinos, the majority of temporal retinal fibers subserving the nasal field (from fixation to an eccentricity of about 20 degrees ) anomalously cross with the nasal retinal fibers. Therefore with monocular stimulation, the evoked visual response should be obtained only in the contralateral hemisphere. The asymmetry, morphology and latency for the first major positive peak and the amplitude of the VEP were examined and compared with the normal population.
CONCLUSION: We managed to demonstrate the characteristic VEP asymmetry only in 3 out of the 16 patients. The results presented herein lead to question the absolute validity of VEP abnormality in diagnosis of albinism for clinical purposes.