Blindness is a feature of the group of storage diseases of children known as the ceroid-lipofuscinoses. Sequential studies in the ovine model, which most resembles the juvenile form of human disease, showed clearly that blindness had two components, a central and a peripheral. Whereas the central component, attributable to neuronal death and atrophy of the cerebral cortex, was responsible for early loss of vision, retinal atrophy was also extremely advanced in terminal stages of the disease. The primary retinal change was one of dystrophy of photoreceptor outer segments which preceded degeneration and necrosis of the photoreceptors cells themselves. Electroretinography showed that there was a progressive loss of a- and b-waves during the course of the disease, but this was preceded by a diminished c-wave which was eventually replaced by a negative potential. However, the pigment epithelium remained functionally (azide responsive) and ultrastructurally intact throughout the study. Loss of brain weight with selective cerebral atrophy also correlated with abnormal behaviour and facial manoeuvres that were interpreted as partial seizures that did not become generalized.

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