Longitudinal evaluation of changes in retinal architecture using optical coherence tomography (OCT) in achromatopsia.

Abstract

Purpose : Controversy exists in the literature as to whether retinal changes in achromatopsia (ACHM) are progressive. The aim of this prospective, observational study is to investigate longitudinal changes in retinal structure in patients with ACHM, using optical coherence tomography (OCT),over a longer follow up period than has been reported previously.

Methods : We enrolled 10 patients, 4 adults (mean age 43.2, range 22-63 years) and 6 children (mean age 8, range 4-10 years), with genetically confirmed ACHM with a follow up time of at least 24 months. All patients underwent spectral domain OCT imaging acquired with Copernicus (OPTOPOL Technology) or handheld OCT (LEICA Envisu system). Retinal layers were segmented and analysed using ImageJ. In each patient central macular thickness, outer nuclear layer (ONL) thickness, changes of the photoreceptor layer (IS/OS junction) and size of foveal hyporeflective zone (HRZ) were measured. The mean age at follow up examination was 48.7years (range 30-65 years) for adults and 13.5 years (range 10-16 years) for children. Mean follow up period was 65.9 months (range 24-103 months).

Results : All participants demonstrated changes in retinal structure between baseline examination and last visit. Over a mean follow-up time of 65.9 months, HRZ demonstrated a 2.5 fold increase in width (p<<0.001, from 197µm to 494µm). A subtle but significant 8% reduction in ONL thickness was observed (p=0.017), but there was no significant change in central macular thickness (p=0.15). In 4 patients(3 children,1 adult) IS/OS showed only minimal discontinuities of photoreceptor layers at the first examination which progressed to a HRZ at follow up. In 2 patients (1 child, 1 adult) hyper-reflective changes were detected at baseline visit which progressed to IS/OS disruption and subsequently to a HRZ at the last visit. OCT revealed asymptomatic retinal rupture in 1 adult patient at follow up.

Conclusions : Using the longest follow up period reported to date our study demonstrates clear longitudinal changes in foveal structure in both children and adults with ACHM. The understanding of the time course of the morphology of photoreceptor changes in ACHM is likely to have important implications for guidance for gene therapy.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.