“Take your vitamins” is almost always a good recommendation, but if you have retinitis pigmentosa (RP), you need to be a little choosy about which vitamins you take.
A 1993 study showed that taking 15,000 IU of vitamin A each day was very helpful for RP sufferers. Taking any more vitamin A than this recommended dose did not appear to be beneficial.
On the other hand, taking vitamin E (the study focused on intake of 400 IU per day) can actually accelerate the course of the disease and cause vision to deteriorate at a faster rate.