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Muhammad Sohail Halim, Muhammad Hassan, Rubbia Afridi, Nam V Nguyen, Arash Maleki, Sean Christopher Baluyot, Yasir Jamal Sepah; Scleral Vessel Density Using Novel Optical Coherence Tomography Angiography Methodology. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2825.
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© ARVO (1962-2015); The Authors (2016-present)
To develop and assess the reliability of a novel acquisition protocol to image scleral vasculature and measure scleral vessel density in eyes with no known pathology.
Sclera from Twenty (20) eyes of 10 subjects were scanned with the Optovue AngioVue Imaging System (Optovue, Inc., Fremont, CA). Two (2) eyes were excluded from the analysis due to motion artifacts in the optical coherence tomography angiography (OCTA). With the anterior segment lens mounted, the retina map 3.0 scan was selected. Follow-up was turned off while tracking was kept on. Internal illumination light was turned off. The Z value was increased to maximum while focus was lowered to minimum. External fixation light was used to fixate the eye at approximately 45o from the primary gaze. The red external fixation light was shined on the anterior portion of the eye to get a better-quality IR image. OCTA images were captured of the temporal portion of sclera near the edge of limbus (Figure 1). Each eye was imaged by two independent operators after adequate training of the methodology was provided. Paired sample t-test was applied to compare the difference of vessel density between graders. The limits of agreement were plotted against difference between the operators. The Stanford’s institutional review board (IRB) had approved the study.
The mean age of the study population was 35.66 ± 13.42 years. 50% (9) eyes were of female subjects. The mean scleral vessel density was 54.62 ± 3.69%. There was no statistical difference in the vessel densities for gender (p-value:0.29). The mean scleral vessel density for operator 1 and operator 2 was 55.05 ± 3.34% and 54.20 ± 4.06% respectively. There was no statistical difference in the scleral vessel density measurements between the graders (p-value: 0.17). Bland-Altman plot showed that all, but one vessel densities were within the limits of agreement (Figure 2).
Our methodology can be reliably utilized to image scleral vessels and assess scleral vessel densities.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
Figure 1: Scleral Optical Coherence Tomography Angiography (OCTA) Image
Figure 2: Bland-Altman plot showing difference of vessel densities between the operators
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