Automated Measurement of Iris Surface Smoothness Using Anterior Segment Optical Coherence Tomography
Elyas Khalili Pour1 , Mohammad Zarei1 , Tahereh Mahmudi2 , Hamid Riazi-Esfahani1 , Behnam Mousavi2 , Nazanin Ebrahimiadib1 , Mehdi Yaseri3 , Hossein Arabalibeik2 *
- Retina Service, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran
- Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences and Reasearch Center for Science and Technology in Medicine, Tehran, Iran
- Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
Abstract: To present an automated method in a observational case series to measure the smoothness index (SI) of iris surface in anterior segment optical coherence tomography (AS-OCT) images.
Methods: In a uveitis referral center twenty-two eyes of 11 patients with unilateral Fuchs uveitis (FU) (7 female) and 22 eyes of 11 healthy control subjects underwent AS-OCT imaging. The ratio of the length of the straight line connecting the most peripheral and central points of the anterior iris border (in nasal and temporal sides) to the actual length of this border on AS-OCT images, was defined as SI. Image J and a newly developed MATLAB algorithm were used for manual and automated SI measurements, respectively. Agreement between manual and automated measurements was evaluated with Bland-Altman analysis and interclass correlation coefficient. The inter-eye difference of SI was compared between FU group and control group.
Results: Automated mean overall SI was 0.868 ± 0.037 and 0.840 ± 0.039 in FU and healthy fellow eyes, respectively (estimated mean difference = -0.028, 95% CI [-0.038, -0.018], p<0.001). Bland- Altman plots showed good agreement between two methods in both healthy and FU eyes. Interclass correlation coefficient between the manual and automated measurements in the FU and healthy fellow eyes was 0.958 and 0.964, respectively. Inter-eye difference of overall SI was 0.029 ± 0.015 and 0.012 ± 0.008 in FU group and control group, respectively (p=0.01).
Conclusion: The automated algorithm can rapidly and conveniently measure SI with results comparable to manual method.
