Retinal and choroidal morphological changes in Huntington's disease

Abstract

Purpose: to investigate the choroidal and retinal morphology in Huntington's disease (HD) using optical coherence tomography (OCT) and to analyze how the parameters studied correlate with the clinical data. Material and methods. The study included two groups of subjects, (1) 44 HD patients, averagely aged 37.6 ± 10.2 yrs, and (2) 31 healthy volunteers, averagely aged 37.3 ± 10.8 yrs. The groups had matching age, sex distribution, intraocular pressure and mean refractive error. In the study group, 21 patients had pre-manifest and 23, manifest HD stage. All patients underwent a thorough neurological and ophthalmic examination which included retinal OCT. The foveal choroidal thickness, retinal thickness in 9 areas of the macular zone, retinal ganglion cells complex (GCC) and peripapillary retinal nerve fiber layer thickness (RNFL) were evaluated in 4 quadrants. CAG repeat expansion size (cytosine-adenine-guanine) in the huntingtin gene, the disease duration and Unified HD Rating Scale motor scores (UHDRS) were evaluated for HD patients. Results. The range of the CAG repeat expansion size in the study group was 37–56 repeats (44.3 ± 3.8), the UHDRS motor score was 36.3 ± 29.7, disease duration was 13.7 ± 7.2 years. OCT revealed a significant decrease in the foveal choroidal thickness, GCC complex thickness, average, temporal, inferior and nasal RNFL thickness and total retinal thickness in the external temporal area in HD patients as compared to the controls. In addition, an inverse correlation between the disease duration, UHDRS Motor Score and a number of OCT parameters was found. Conclusion. The results confirm the promising potential of retinal tomographic parameters as a biomarker for early diagnosis and monitoring of the neurodegenerative process progression. The topography of retinal thickness reduction indicates a specific pattern of retinal neurodegeneration in HD.