Safety Study in Retinal Transplantation for Retinitis Pigmentosa.

The aim of this clinical trial is to test the safety of transplanting human fetal neural retinal tissue and retinal pigment epithelium into the eyes of human patients with retinitis pigmentosa. Vision in the eye to be operated on will be the poorer vision of both eyes and must be 20/200 or worse. "Retinal tissue", the layers in the back of the eye, consists of neural retina and retinal pigment epithelium. "Neural retina" is the nerve cell layer that processes light into vision. The "photoreceptor cells" in the neural retina detect the light and transform it into electrical signals, which are then transferred to the brain by other retinal cells. "Retinal pigment epithelium" (RPE) is the layer behind the neural retina which helps both to nourish the cells of the neural retina and also to get rid of waste products. The fetal tissues used in this study will be derived from dead fetuses in the first 9-16 weeks of pregnancy obtained from elective abortions.

Fetal retinal transplantation is highly experimental. The research will be conducted in accordance with the prohibitions regarding the use of human fetal tissue described in Public Law 103-43, section 498B. There will be no compensation for the donor. The research will be conducted in accordance with any applicable Federal, State and local laws.

First, the technical application of the implantation instrument and its safety in the transplantation will be demonstrated in patients with 20/200 vision in one eye or worse, with functional acuity in the contra lateral eye.

Secondly, the human fetal retinal tissue will be placed in the areas beneath the retina where presently the patient has atrophy of the retinal pigment epithelium and poor retinal function.

Inclusion criteria

• The subject must have decreased central visual acuity of 20/200 or worse in one eye by ETDRS vision testing for a duration of at least one year in the operated eye and have the diagnosis of retinitis pigmentosa; vision in the nonoperated eye must be better than the operated eye. Vision in the operated eye cannot be better than 20/200.
• Subject is older than 21 years of age
• Patient is willing to return for follow-up visits
• Patient has signed informed consent for retinal transplantation
• Patient has undergone microperimetry and Goldmann visual field testing.

Exclusion criteria

• Patient having a central visual acuity of better than 20/200 in one eye by ETDRS or vision worse than 20/200 in one eye by ETDRS for a duration of less than one year
• Unwilling to sign an informed consent
• Patient under 21 years of age
• Patient having medical problems that are contraindicatory for short-term anesthesia
• Patient unwilling to return for follow-up visits
• The patient has been determined to be pregnant by patient history or by pregnancy testing in women of childbearing potential
• A tear of the retinal pigment epithelium
• Any significant ocular disease that has compromised or could compromise vision in the study eye and confound analysis of the primary outcome
• Inability to obtain photographs to document fundus condition, including difficulty with venous access
• Participating in another ophthalmic clinical trial or use of any other investigational new drugs within 12 weeks before the start of study treatment
• Intraocular surgery within the last two months or capsulotomy within the last month in the study eye
• Patient who has a history of uveitis, Coat's disease, diabetic retinopathy, glaucoma, or a cataract that prevents visualization of the posterior pole