Abstract
Purpose: :
Precise outer retina imaging in combination with functional assessment can provide new insights regarding structure and function relation of the outer retina in patients with confirmed ABCA4 gene mutations, marked by huge phenotypic variability. The purpose of this study was to develop new imaging modalities for the outer retina structure and function mapping in patients with confirmed ABCA4 gene mutations.
Methods: :
Prospective observational cross-sectional study included 36 eyes of 18 patients’ (mean age 33±9years) with confirmed ABCA4 gene mutations. All patients underwent in-depth phenotype examination. The VERIS system was used to record electroretinograms (mfERG) as a measure of outer retinal functional output. Spectral-domain optical coherence tomography (SD-OCT) was used to evaluate outer retina morphological changes. The raw data were exported and semi-automatical approach was applied to assess outer retina structural and functional maps based on a fusion matrix consisting of 210 matched points in a radius of 20 grad. from fixation point. As obtained with mfERGs, negative-to-positive component (N1P1) amplitude and SD-OCT inner/outer segment thickness, functional and structural maps were assessed and classified as mild, moderate and severe in changes for particular individual. The inter-observer and intra-observer reliability of the semi-automatic mapping approach was determined. The probability of the correct functional and structural mapping was compared with an expert decision support system.
Results: :
In patients with confirmed ABCA4 gene mutations the mean area of mild, moderate and severe functional output changes was 12.817±7.325, 23.972±9.840, 30.414±12.213 pixels (p<0.05), whereas structural output changes was 1.425±766, 9.201±4454, 150.015±17647 pixels, respectively (p<0.05). The intra-observer and inter-observer agreement of the semi-automatic mapping approach was 0.95 and 0.98, respectively. The probability of correct functional and structural mapping was 0.97 (95% Confidence interval 0.94, 0.99, p<0.01) and it was comparable with an expert decision support system (0.98 (96% Confidence interval 0.99, p<0.01).
Conclusions: :
Severe outer retinal structural and functional changes were observed in patients with confirmed ABCA4 gene mutations. The developed mapping approach proved to be a reliable tool for assessing outer retina structural and functional output maps, and can be used as a precise inclusion criterion in therapeutic trials for an individual subject.
Keywords: photoreceptors • computational modeling • retinal degenerations: hereditary