Are you looking for a specific condition? Refsum? Retinitis pigmentosa? Friedrich ataxia? Abetalipoproteinemia? How old is the child?
It is not for me but for my friend in Poland, so unfortunately I am not sure which of these would apply. The child is 6 years old. I only know that the condition is also known as Neuropathy 2
Most of these really have no treatment, other than supportive (low vision aids when the disease progresses and occupational aids). There are also specific supportive aids if the disease has other neurologic manifestations (e.g. seizures, ataxia, etc.). Some have advocated vitamin A and Vitamin E for the retinal part.
Perhaps in the futures, gene therapy?...