I am sorry there is no definitive treatment for RP. There are many experimental treatment likes stem cell transplant , bionic eye etc still under study. In initial stages there are some study suggesting Vit A and Vit E supplementation can slow the progression of disease. RP can be associated with cataract especially PSC(posterior subcapsular cataract), probable theory of toxins causing both. As vision is compromised due to RP, cataract surgery should be performed with caution. Other treatment you mentioned above are visual rehabilitative measures , they are very effective if used on time under continuing therapy to keep patient functional. RP is devastating diseases but realistic approach and good visual rehab, it will not affect life much if you accept and be positive. All the best Regards