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Jason C Park, Frederick T Collison, Gerald A Fishman, Rando Allikmets, Jana Zernant, J Jason McAnany; Objective analysis of outer retinal layers imaged by optical coherence tomography in patients with Stargardt disease.. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):587. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To develop and apply an objective, semi-automated algorithm for analyzing outer retinal layers imaged by spectral domain optical coherence tomography (SD-OCT) in patients with Stargardt disease.
Horizontal macular B-scans were acquired (Optos SD-OCT/SLO) from 22 normal controls and 20 genetically confirmed patients with stage 1 Stargardt disease. The number of hyper-reflective, outer-retina bands was quantified for each subject using a novel, semi-automated algorithm. The algorithm detected the number of hyper-reflective bands based on longitudinal reflectance profiles (LRPs) as follows: 1) LRPs were generated by averaging 43 adjacent A-scans (305 µm in width); 2) The number of bands was quantified based on the second derivative of the LRP. The present analysis focused on the 3 outermost retinal bands, currently associated with the retinal pigment epithelium complex (RPE), the cone outer segment/RPE interdigitation zone (IZ), and the ellipsoid zone (EZ). To validate the algorithm, band detection was also determined manually by four graders.
The semi-automated algorithm and manual analysis showed excellent agreement. The RPE and EZ bands were detected throughout the entire B-scan in all controls. The RPE band was detected throughout the entire B-scan in all Stargardt patients, whereas the EZ band was detected only outside the central lesion. The extent of IZ band detection differed throughout the B-scan for the controls and patients. That is, IZ detection for controls was greatest in the para- and peri-foveal regions (0.5 to 2.6 mm from the fovea), with a mean detection over these areas of 82%. IZ band detection for the controls decreased towards the fovea and near-periphery (mean detection over these areas of 50% and 55%, respectively). In patients, the IZ band was generally not present in the fovea, para-, or peri-fovea due to the central lesion. Outside of the lesion, the IZ band was detected in 26% of the patients (mean detection across the near-periphery), which is less than half of the detection in controls.
An objective, semi-automated approach can be used successfully to quantify the number of hyper-reflective, outer-retina OCT bands. The IZ band is less frequently detected in Stargardt patients compared to controls, even outside the central lesion, suggesting abnormalities in outer segment structure and/or RPE interdigitation.
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