High-Resolution In Vivo Imaging in Achromatopsia

Purpose: To characterize the retinal changes in patients with achromatopsia using an ultrahigh-resolution (UHR) spectral-domain optical coherence tomography (OCT) to examine how human achromatopsia corresponds to its animal model. Design: Comparative case series. Participants and Controls: Ultrahigh-resolution OCT (Copernicus; OPTOPOL Technology S.A., Zawiercie, Poland; 3-mu m axial resolution) was used to obtain scans from 13 patients (26 eyes) with achromatopsia and from 20 controls (40 eyes). Methods: A 3-dimensional scan program (743x75; AxB scan) sampling a 7x7-mm retinal area centered at the fovea was used to obtain tomograms of the fovea. Individual B-scans at the fovea were exported and analyzed using ImageJ (Wayne Rasband, National Institute of Health) for reflectance profiles and morphologic abnormalities. Main Outcome Measures: Gross morphologic changes in OCT were characterized. Specifically, inner segment and outer segment (IS/OS) junction and cone outer segment tip (COST) disruption was noted. Using the reflectance profiles, foveal depth, thickness of the outer nuclear layer (ONL), and retinal thickness (RT) were measured. Results: A characteristic so-called punched out hyporeflective zone (HRZ) was noted in 7 of 13 patients; this was age-dependent (P = 0.001). The area of the HRZ was asymmetric with the nasal area being significantly greater than the temporal area (P = 0.002). In all patients, there was disruption of the IS/OS junction at the foveal or parafoveal regions, or both. Five of 13 patients also had a disrupted COST reflectivity. There was significant (P = 1.1x10(-6)) ONL thinning in the achromats compared with controls, which was age-dependent (P = 0.0002). Foveal maldevelopment was seen in 9 of 13 patients. The achromats also had a significantly reduced foveal depth (P = 7.7x10(-6)) and RT (Px1.46x10(-9)) compared with controls. Conclusions: A range of signs in achromatopsia are described that can be detected using UHR OCT. The IS/OS junction and COST reflectivity disruption and presence of HRZ and ONL thinning are signs of cone photoreceptor degeneration. The latter 2 are age-dependent, which suggests that achromatopsia is a progressive disorder. In addition, foveal maldevelopment is described; this represents a fetal developmental defect linked to cone photoreceptor degeneration. Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article. Ophthalmology 2011;118:882-887 (C) 2011 by the American Academy of Ophthalmology.