Although it is generally believed that it is not possible to treat choroideremia by conventional therapy, a clinical trial of gene therapy using a viral vector for REP1 has been reported to be relatively successful.1 Choroideremia is associated with a degeneration of the RPE and choriocapillaris throughout the fundus.2–6 However, it is unclear whether the RPE or choriocapillaris is the first structure to be altered. This evidence concerns the gene CHM and choroideremia.