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Selin L Auvazian, Preny Karamian, Jennifer Cano, Sophie Leahy, Amir H. Kashani, Andrew A Moshfeghi, Hossein Ameri, Norman P Blair, Mahnaz Shahidi; Relating retinal vessel oxygenation and tortuosity at progressive stages of diabetic retinopathy. Invest. Ophthalmol. Vis. Sci. 2019;60(9):3025.
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© ARVO (1962-2015); The Authors (2016-present)
Diabetic retinopathy (DR) is one of the most common causes of vision loss in adults. Diabetes has been shown to affect the retinal microvasculature morphology. However, the relationship between changes in retinal vessel morphology and oxygen content is not known. The purpose of the study was to test the hypothesis that there is an association between retinal vessel tortuosity and oxygen saturation in DR.
Thirty-seven subjects participated in the study and were classified in 4 groups: non-diabetic (N=7), no DR (N=9), non-proliferative DR (NPDR; N=16), and treated proliferative DR (PDR: N=5). Dual wavelength oximetry was performed to measure retinal arterial and venous oxygen saturation (SO2A, SO2V) within a circumpapillary region and calculate oxygen extraction fraction (OEF). Optical coherence tomography angiography (OCTA) was performed in a 6mm x 6mm perifoveal region. OCTA images of the superficial capillary layer were analyzed to calculate vessel tortuosity index (VTI) based on the angle between vessel tangent and horizontal axis, number of critical points, and the ratio of vessel to chord length. Data in one eye of each subject was randomly selected for ANOVA and Pearson correlation analyses.
Subjects in the 4 groups (non-diabetic, no DR, NPDR, PDR) were similar in age (mean ± standard deviation=58±15 years; p=0.37; N=37). Among the 4 groups, there were no statistically significant differences in SO2A (91± 2.6%, 95±9.2%, 95±10%, 104±14%; P=0.19) and SO2V (55± 3.1%, 57±9.8%, 56±12%, 62±8.3%; P=0.62). Likewise, OEF (0.40±0.03, 0.41±0.08, 0.41±0.11, 0.40±0.06; P=1.0) and VTI (0.40±0.03, 0.56±0.20, 0.52±0.14, 0.54±0.18; P=0.20) were also not statistically different among groups. There was a positive correlation between VTI and SO2V (R = 0.50, p=0.002; N=37) and a negative correlation between VTI and OEF (R = - 0.37, p=0.02, N=37).
Our results showed that increased retinal vessel tortuosity is associated with increased venous oxygenation and decreased oxygen extraction fraction, suggesting these changes are related to the same component of diabetes pathophysiology.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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