Multimodal Imaging of Photoreceptor Structure in Choroideremia

• Published in: PloS one Vol. 11; no. 12; p. e0167526
• Main Authors: Sun, Lynn W., Johnson, Ryan D., Williams, Vesper, Summerfelt, Phyllis, Dubra, Alfredo, Weinberg, David V., Stepien, Kimberly E., Fishman, Gerald A., Carroll, Joseph
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 09.12.2016; Public Library of Science (PLoS)
• Subjects: Adaptive optics; Adaptor Proteins, Signal Transducing - genetics; Adult; Aged; Albinism; Analysis; Atrophy; Biology and Life Sciences; Biomedical engineering; Biophysics; Borders; Choroideremia; Choroideremia - genetics; Choroideremia - pathology; Cones; Confocal; Degeneration; Dystrophy; Epithelium; Gene mutation; Genetic aspects; Humans; Image resolution; Lesions; Male; Males; Medical imaging; Medicine and Health Sciences; Middle Aged; Morphology; Multimodal Imaging - methods; Mutation; Neurobiology; Neurosciences; Ophthalmoscopy - methods; Optical Coherence Tomography; Optical tomography; Optics; Photoreception; Photoreceptors; Physicians; Reproducibility of Results; Retina; Retina - diagnostic imaging; Retina - pathology; Retinal Cone Photoreceptor Cells - pathology; Retinal degeneration; Retinal Degeneration - diagnostic imaging; Retinal Photoreceptor Cell Inner Segment - pathology; Retinal pigment epithelium; Science; Segments; Sensitivity and Specificity; Sensors; Social Sciences; Structure; Studies; Thinning; Tomography; Tomography, Optical Coherence - methods; Young Adult
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0167526

Choroideremia is a progressive X-linked recessive dystrophy, characterized by degeneration of the retinal pigment epithelium (RPE), choroid, choriocapillaris, and photoreceptors. We examined photoreceptor structure in a series of subjects with choroideremia with particular attention to areas bordering atrophic lesions. Twelve males with clinically-diagnosed choroideremia and confirmed hemizygous mutations in the CHM gene were examined. High-resolution images of the retina were obtained using spectral domain optical coherence tomography (SD-OCT) and both confocal and non-confocal split-detector adaptive optics scanning light ophthalmoscope (AOSLO) techniques. Eleven CHM gene mutations (3 novel) were identified; three subjects had the same mutation and one subject had two mutations. SD-OCT findings included interdigitation zone (IZ) attenuation or loss in 10/12 subjects, often in areas with intact ellipsoid zones; RPE thinning in all subjects; interlaminar bridges in the imaged areas of 10/12 subjects; and outer retinal tubulations (ORTs) in 10/12 subjects. Only split-detector AOSLO could reliably resolve cones near lesion borders, and such cones were abnormally heterogeneous in morphology, diameter and density. On split-detector imaging, the cone mosaic terminated sharply at lesion borders in 5/5 cases examined. Split-detector imaging detected remnant cone inner segments within ORTs, which were generally contiguous with a central patch of preserved retina. Early IZ dropout and RPE thinning on SD-OCT are consistent with previously published results. Evidence of remnant cone inner segments within ORTs and the continuity of the ORTs with preserved retina suggests that these may represent an intermediate state of retinal degeneration prior to complete atrophy. Taken together, these results supports a model of choroideremia in which the RPE degenerates before photoreceptors.