Foveal Phenotypes in Choroideremia on Adaptive Optics Scanning Light Ophthalmoscopy

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 pathophysiologic 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 with those from standard clinical imaging. Visual acuity was also measured and compared with 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 optical coherence tomography (r2 = 0.47, P = 0.0009) and inversely related to visual acuity (r2 = 0.20, P = 0.001). Conclusion: 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.

Parafoveal cone function in choroideremia assessed with adaptive optics optoretinography

“…Thus, the number of cones used in the ORG measurement is not the cause of the reduced ORG amplitudes for CHM participants. Reduced central cone density has been proposed as a marker of disease severity in CHM 10 . The positive correlation between cone density and ORG amplitude gives credence to the idea that ORG amplitude may also be a marker of disease severity in this patient population.…”

“…Ten genetically confirmed CHM (ages: 20–49 years; all males) and four normal-sighted subjects (ages: 30–57 years; three males, one female) participated in the study. Genetic mutations for all participating CHM patients are reported in Wynne et al 10 All participants provided informed consent after learning the nature and possible consequences of the study. Only one eye per participant was included in the study.…”