Abstract
Purpose: :
To compare volume and macular thickness measurements obtained from time domain optical coherence tomography (OCT) and a custom-built OCT Retinal Image Analysis software
Methods: :
Ten eyes of 5 healthy subjects underwent repeated standard Macular Thickness Map scan sessions by 1 experienced examiner using a Stratus OCT device. Automatic/semi-automatic thickness quantification of the macula and intraretinal layers was performed in each eye by one grader using a custom-built OCT Retinal Image Analysis software. Thickness measurements in our custom-built OCT analysis software were obtained by calculating the thickness between ILM and RPE (inner boundary), whereas automated Stratus OCT results are currently calculated between ILM and ONL (outer boundary). Macular volume and total and regional macular thicknesses obtained by the Stratus OCT and the custom-built image analysis software were compared using the true anatomic location of the outer retinal boundary. In addition, their agreement with frequency-domain measurements was evaluated.
Results: :
After comparing Stratus OCT macular thickness measurements with the measurements obtained using the true anatomic location of the outer retinal boundary, the mean thickness difference was 27 µm (ranged, 18-32 µm). Similar thickness differences have been found between Stratus OCT and SD-OCT systems, which use the same method of the custom-built software to calculate the macular thickness. Mean difference values per macular region included only 8-17 % of the measured total values obtained by the commercial Stratus OCT system. Total macular volume, a measure derived from thickness in all data point of the macula, was 10% higher by our custom-built software compared to Stratus OCT results, also supporting an average difference of 10% in thickness measurements.
Conclusions: :
Our results demonstrate the reliability of the custom-built software when compared to SD-OCT systems. According to our results, the custom-built software is a good candidate for potential studies examining OCT morphologic characteristics of changes in retinal structure.
Keywords: image processing • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina