Surgical Approach with Pars Plana Vitrectomy for Subretinal Gene Therapy.

Gene therapy is emerging as a treatment for inherited diseases including retinitis pigmentosa. Through surgery, specifically with pars plana vitrectomy, the subretinal space can be accessed to directly administer this treatment. The goal herein is to provide an overview of this approach.

Vitamin A deficiency and the retinal "double carrot" sign with optical coherence tomography.

BACKGROUND: Spectral-domain optical coherence tomography (SD-OCT) and full-field electroretinography (ERG) allow retinal assessment with vitamin A deficiency (VAD). Using SD-OCT, this study aimed to characterize and follow a novel retinal abnormality in patients with VAD and intramuscular supplementation. METHODS: Patients with VAD were retrospectively reviewed, including SD-OCT and electroretinography. RESULTS: Three patients had VAD following bariatric or colon surgery and varying supplementation. All had nyctalopia, extinguished scotopic rod-specific function with ERG, and decreased serum vitamin A. None demonstrated surface abnormalities. All received intramuscular vitamin A with subjective resolution of symptoms. On SD-OCT, four of six eyes exhibited homogenous foveal hyperreflectivity anterior to retinal pigment epithelium-Bruch complex, reminiscent of a "double carrot", which improved following supplementation. ERG findings demonstrated improved scotopic rod-specific function in all cases; however, photopic function remained diminished in two cases. CONCLUSIONS: Structural improvement of the proposed "double carrot" sign occurs soon after vitamin A supplementation. While scotopic function improves rapidly following supplementation, cone function recovers more slowly. Therefore, foveal changes such as the "double carrot" sign suggest that structural recovery of cones precedes functional recovery.