is the most common retinal dystrophy. The most common symptom is night blindness
. Ophthalmoscopy demonstrates attenuation of the retinal vessels, retinal pigmentary changes consisting of bone-corpuscular clumping of pigment in the midperiphery of the fundus, and waxy pallor of
the optic disks. The visual fields show annular scotomas. The scotopic ERG is primarily affected; the photopic ERG is relatively spared. Patients tend to lose more rod than cone function in the early stages, as noted by ERG. This condition can be detected after age 6 based on abnormal ERGs often years to a decade before symptoms develop. Treatment
of adults with 15,000 international units (IU) of vitamin A, in the palmitate form
, on average, slows the progression of the disease. Doses for 6 year olds are 5,000 IU/day and for 10 year olds 10,000 IU/day. The website www.fightblindness.org/RetinitisPigmentosa/ lists mail-order companies that provide vitamin A palmitate in 15,000 IU capsules or tablets, as the correct dose is not available in most food stores. Note that beta carotene is not
a suitable substitute for palmitate vitamin A. In addition, high-dose vitamin E (400 IU/d) appears to have an adverse effect on the course of this condition. Use of vitamin A can add 7 years of vision, and vitamin A plus two 3-oz servings of oily fish per week (sardines, tuna, mackerel, salmon, herring) can add 20 years of vision in RP patients. No toxic side effects have been reported with these vitamin A doses, but liver function and fasting serum vitamin A should be obtained once yearly.