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.