Abstract
Purpose: Retinal structure and function deficits in carriers of X-linked retinitis pigmentosa (RP) caused by mutations in RPGR have been shown to be heterogeneous. One particularly interesting feature is the retinal tapetal-like reflex (TLR).[1–3] In this study we assessed the photoreceptor mosaic changes in a group of unrelated obligate carriers of X-linked RP and examined the TLR patterns using multimodal retinal imaging.
Methods: Female carriers of X-linked RP and unaffected females underwent multimodal ophthalmic imaging including spectral domain optical coherence tomography (SDOCT) and fundus autofluorescence imaging. Adaptive optics scanning light ophthalmoscope (AOSLO) images of the photoreceptor mosaic were obtained for the fovea and temporal parafoveal region.
Results: Nine female carriers (age 28–61) and three non-carrier females (ages 23–35) were examined. A TLR was clinically detectable in all but one carrier. One subject had reduced acuity due to RPGR associated degeneration. On SDOCT, inner segment ellipsoid (ISe) and retinal pigment epithelium (RPE) local contrast was reduced in areas of TLR. AOSLO images showed zones of decreased cone density with mosaic irregularity and increased photoreceptor reflectivity. Increased reflectivity on AOSLO was co-localized to areas of TLR. No localized areas of decreased density or increased reflectivity were seen in non-carrier females.
Conclusion: AOSLO reflectance patterns in X-linked carriers of RP appear to identify the cellular origin that underlie the TLR. Similar cellular changes have been observed with AOSLO in affected males [4], which, supports the notion that such reflexes are related to random X-inactivation in females.
The work was supported by grants from the National Institute for Health Research Biomedical Research Centre at Moorfields Eye Hospital National Health Service Foundation Trust and UCL Institute of Ophthalmology, a multiuser equipment grant from The Wellcome Trust [099173/Z/12/Z], National Institutes of Health (US) grants R01EY017607, P30EY001931, C06RR016511, Fight For Sight (UK), Moorfields Eye Hospital Special Trustees, Moorfields Eye Charity, the Foundation Fighting Blindness (USA), Retinitis Pigmentosa Fighting Blindness, Research to Prevent Blindness (RPB), Michel Michaelides is supported by an FFB Career Development Award. This project was supported in part by the National Center for Advancing Translational Sciences, National Institutes of Health, through grant UL1TR000055.