Abstract
Purpose:
Gene therapeutic approaches for different inherited retinal dystrophies have reached clinical trial status. In Stargardt’s disease, a maculopathy caused by mutations in the ATP binding cassette A4 (ABCA4) gene, current gene replacement strategies aim at restoring function of the ABCA4 protein in order to halt disease progression. Characterizing the therapeutic benefit over time requires objective and highly sensitive tests. The aim of this study was to correlate morphological and functional data of patients with Stargardt’s disease in order to define areas with the highest potential treatment effect.
Methods:
Ten patients with Stargardt’s disease (age 18y - 36y, average: 27) were examined morphologically with a spectral domain OCT (Spectralis, Heidelberg Engineering, Germany), and functionally with fundus controlled perimetry (MP1, Nidek Technologies, Italy). Using our custom made DIOCTA software for OCT raw data analysis, six layers (NFL, GCL+IPL, INL, OPL+ONL+ELM+IS, Junc+OS, RPE) were segmented on volume scans of the macular region in each patient. Spatially resolved thicknesses of all layers were calculated in heat maps. Fundus controlled perimetry was performed at 55 positions in a 10° visual field using 200 ms white Goldman III stimuli. Both results were superimposed.
Results:
Heat maps of the respective thickness values were generated for all six layers segmented with high spatial resolution. Likewise, fundus controlled perimetry allowed detection of light increment sensitivities in defined retinal loci. Superimposing OCT and MP1 data showed good correlation of thinning of outer retinal layers with sensitivity losses at corresponding positions. Inner retinal layer thickness remained normal in areas with reduced sensitivity but progressively also decreased in more severe atrophy of the outer retina.
Conclusions:
Correlation of layer specific morphological data generated with DIOCTA and functional data obtained with fundus controlled perimetry represents a highly sensitive examination tool which may generate important information on the potential outcome of experimental treatment strategies.
Keywords: 550 imaging/image analysis: clinical •
585 macula/fovea •
642 perimetry