Abstract
Purpose:
To estimate disease progression based on analysis of retinal thickness and macular volume measured by SPECTRALIS™ spectral-domain optical coherence tomography (Spectralis OCT) in a prospective longitudinal natural history study in patients affected by Stargardt Macular Dystrophy (STGD).
Methods:
60 eyes of 30 STGD patients were included. The study was approved by the Institutional Review Board. Total macular volume (TMV), retinal thickness and volumes of all nine Early Treatment of Diabetic Retinopathy Study (ETDRS) subfields. 116 macular scans were analyzed. Numbers and types of segmentation errors of the Heidelberg Eye Explorer software (Version 5.4.6) were recorded and manually corrected. In a subgroup of 18 patients, TMV and retinal thickness and volumes of all 9 ETDRS subfields were registrated, differences between visits calculated and difference per time (loss of retinal thickness and volume per year) estimated.
Results:
4424 line scans from 116 macular scans were analyzed. 1373 (31%) of those showed segmentation errors and were manually corrected. Mean observation period was 12 months (range 3 to 34 months). Mean change in TMV (mean baseline=6.713 ± 0.932 mm3 was -0.15 mm3 per year. Mean volume change was -0.007 mm3 per year in the central subfield (mean baseline=0.129 mm3), -0.011 mm3 per year in the inner ETDRS circle (inner four subfields; mean baseline=0.381 mm3), and -0.022 mm3 per year in the outer ETDRS subfields (mean baseline=1.33 mm3). Change of retinal thickness was -7.15 µm per year in the central subfield, -7.21 µm per year in the inner ETDRS circle and -4.68 µm per year in the outer ETDRS circle.
Conclusions:
The Spectralis OCT allows to measure decline in retinal thickness and volume in neurodegenerative disease of the retina such as STGD. However, automated analysis shows segmentation errors in about a third of scans and requires manual correction. The level of variability of OCT-derived measurements of retinal thickness and volume that we observed suggests that an observation period of about 12 months is needed to detected definite progression above the noise level in the majority of patients with STGD. OCT-derived measurements of retinal thickness and volume may serve as outcome measures for clinical trials of clinical intervention that targets the progression of loss of the neuroretina in STGD.
Keywords: 696 retinal degenerations: hereditary •
550 imaging/image analysis: clinical •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)