Reappearance of the tapetal-like reflex after prolonged dark adaptation in a female carrier of RPGR ORF15 X-linked retinitis pigmentosa

PURPOSE To report changes in the tapetal-like reflex in a female carrier of RPGR ORF15 c.3395delA X-linked retinitis pigmentosa (XLRP) between examinations at 16 and 22 years of age, and to report the observation that the tapetal-like reflex faded due to exposure to daylight and reappeared with prolonged dark adaptation at 22 years of age. METHODS Clinical examination, kinetic Goldmann perimetry, dark adaptometry, fundus autofluorescence photography, spectral domain optical coherence tomography (SD-OCT), full-field electroretinography (ffERG), and multifocal electroretinography (mfERG) were performed. RESULTS A female carrier of RPGR XLRP presented with a tapetal-like reflex at age 16. At age 22, the tapetal-like reflex was absent upon examination in daylight; however, the reflex reappeared after 12 h of dark adaptation. Fundus autofluorescence was unremarkable and did not change after prolonged dark adaptation. Full-field electroretinography and dark adaptometry at age 22 demonstrated reduced rod and cone function compared to at age 16. CONCLUSIONS Dark adaptation before fundus photography may enable the detection of a tapetal-like reflex where it is otherwise invisible. The light-dependent fluctuation of a disease-related substance in the photoreceptors should prompt further study of the potential role of light as a modulator of the progression of RPGR XLRP.