Help docs! my sister has retinitis pigmentosa. am i at risk too?

Possibly: You need a genetic analysis. Is it known to be in your family lineage? If not, it is likely recessive, and that means both of your parents (apparently normal - yes?), have one normal and one rp gene. They will produce 25% normal, 25% rp, and 50% carriers (just like them). Find out from sis what she knows about her heredity and of course she wants that infor for her kids sake.