Foveal Phenotypes in Choroideremia on Adaptive Optics Scanning Light Ophthalmoscopy

Abstract

ABSTRACT Purpose: Choroideremia is an X-linked inherited retinal degeneration involving the choriocapillaris, retinal pigment epithelium and photoreceptors. Adaptive optics scanning light ophthalmoscopy allows visualization of retinal structure at the level of individual cells and is well poised to provide insight into the pathophysiological mechanisms underpinning the retinal degeneration in choroideremia. Methods: Foveal adaptive optics scanning light ophthalmoscopy images of 102 eyes of 54 individuals with choroideremia were analyzed. Measures were compared to those from standard clinical imaging. Visual acuity was also measured and compared to quantitative foveal metrics. Results: The 3 distinct phenotypes observed were: relatively normal (5 eyes, 4 individuals), spiderweb (9 eyes, 7 individuals) and salt and pepper (87 eyes, 47 individuals). Peak cone density (86 eyes of 51 individuals) was significantly lower in choroideremia than in healthy retinas (p<0.0001, range: 29,382-157,717 cones/mm2). Peak cone density was significantly related to extent of retained ellipsoid zone on en face OCT (r2=0.47, p=0.0009) and inversely related to visual acuity (r2=0.20, p=0.001). Conclusions: Distinct phenotypes can be observed on adaptive optics scanning light ophthalmoscopy imaging in choroideremia that cannot always be discerned on standard clinical imaging. Quantitative measures on adaptive optics imaging are related to the structural and functional severity of disease.