Retinitis Pigmentosa (RP)
Here's your citation in American Psychological Association (APA) format:
Retinitis Pigmentosa (RP). (n.d.). In Alleydog.com's online glossary. Retrieved from: https://www.alleydog.com/glossary/definition-cit.php?term=Retinitis+Pigmentosa+%28RP%29