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Radhika Ragam, Bernard Szirth, Albert S Khouri, Kelly A Soules; Measuring asymmetry of the foveal avascular zone in subjects with Type 1 Diabetes Mellitus using OCTA. Invest. Ophthalmol. Vis. Sci. 2017;58(8):652.
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© ARVO (1962-2015); The Authors (2016-present)
Foveal avascular zone (FAZ) varies among healthy subjects (0.02 to 0.63mm2), and enlarges in subjects with Type 1 Diabetes Mellitus (T1DM). Optical coherence tomography angiography (OCTA) can measure XY values, asymmetry, and shape of the FAZ in subjects with T1DM. The aim was to study FAZ asymmetry in relation to age, gender, duration of T1DM, and most recent HbA1c level.
We analyzed 111 subjects (37 males and 74 females) with T1DM ranging from 6 to 54 years old, and a mean HbA1c of 7.61. Eyes were imaged and post capture analysis was performed using proprietary software in the AngioVue OCTA system. Only high quality FAZ images were included. Subjects with acceptable bilateral FAZ images underwent asymmetry grading based on clearness of contour and direction of largest diameter of the FAZ. The grading scale was: 0 for no asymmetry, 1 for mild asymmetry, 2 for moderate asymmetry, and 3 for severe asymmetry. One-way ANOVA and Tukey post-hoc tests were used to determine if subjects from each group (0-3) had significant differences in their duration of T1DM, age, and last HbA1c. An independent-sample T-test was used to determine if males or females showed more FAZ asymmetry.
More asymmetric FAZ was associated with longer duration of T1DM. Statistically significant differences were found in the duration of T1DM between score group 0 and 2 (p<0.001), 0 and 3 (p<0.001), 1 and 2 (p<0.001), and 1 and 3 (p<0.001). No significant difference in the duration of T1DM was found between score groups 0 and 1, and 2 and 3. There was a significantly higher average age in score group 2 than 0 (p<0.001), 3 than 0 (p<0.001), 2 than 1 (p=0.002), and 3 than 1 (p=0.001). Overall the average ages for score groups 0-3 were 15.0, 19.2, 24.1, and 33.6, respectively. No significant difference between gender or most recent HbA1c level was found with increasing asymmetry of the FAZ.
Duration of T1DM correlated with increasing asymmetry of the FAZ. In subjects with T1DM, enlargement and increasing asymmetry of the FAZ may reflect microinfarction of the vascular arcades due to longer duration of T1DM. FAZ Asymmetry due to interruptions in the retinal vasculature capillary network may be observed by OCTA, and used as a valuable screening tool for tracking eyes over time of subjects affected by T1DM. Future studies will concentrate on gender and shape of the FAZ.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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