Study of Oral Minocycline in Treating Bilateral Cystoid Macular Edema Associated With Retinitis Pigmentosa

Background: \- Some people with retinitis pigmentosa (RP) have macular edema (swelling) in the central retina. This can cause decreased central vision. The cause of macular edema is unknown, but may involve inflammation. The drug minocycline might help prevent inflammation and therefore might help treat macular edema and improve central visual function . Objectives: \- To see if minocycline helps people with RP and macular edema. Eligibility: \- People 12 years and older with RP who have macular edema in at least on eye. Design: * Participants will be screened with medical and eye disease history. They will have an eye exam and blood tests. One eye with macular edema will be the study eye. If both eyes are affected, one will be designated the study eye. * Participants will visit the clinic at least 9 times over at least 14 months. The first 3 study visits will be monthly, then every 2 months. * Participants will start taking minocycline after visit 3. They will take 1 pill twice daily for at least 1 year. * Participants will keep a medicine diary and bring it to each visit with their pill bottle and unused pills. At each study visit, participants will have some or all of the following tests: * eye and thyroid exams * blood and pregnancy tests * microperimetry: participants will press a button when they see a light on a computer screen * visual field measurement: participants will look at spots on a white screen to test side vision * electroretinogram: A person will be dark adapted by sitting in the dark for 30 minutes. After the placement of numbing eye drops, special contact lenses will be placed . The participant will watch flashing lights and recordings will be made.