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Anthony N Kuo, Alice Liu, Chee Wai Wong, Ryan P McNabb, Shu Yen Lee, Gemmy Chui Ming Cheung, Seang-Mei Saw, Quan V Hoang; Curvature Differences in Myopic Eyes With and Without Staphyloma using OCT. Invest. Ophthalmol. Vis. Sci. 2019;60(9):4356.
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© ARVO (1962-2015); The Authors (2016-present)
Pathologic myopia is a vision threatening complication of high myopia. Staphylomas – thinning of the posterior eye wall with deformation – are one sign of pathologic myopia (PM). In epidemiological studies, staphylomas can be difficult to identify on the 2D fundus photos typically used for grading PM severity. Research-grade ultra wide-field OCT has been described to identify the edges of staphylomas, but such systems are not widely available. We hypothesized that retinal curvature information from commercially available, standard field of view OCT systems could show differences between myopic eyes with and without staphylomas.
OCT images (Topcon Triton) from high myopia patients with and without staphylomas, as determined on clinical examination by a retinal specialist, were identified from a single specialty high myopia clinic under an IRB approved protocol. A single central B scan for each subject was selected. Each image was corrected for scan geometry and scaling to remove variations due to those distortions; complex conjugate artifacts were cropped. The RPE was segmented and global measures of curvature (radius of curvature [Rc], asphericity [Q]) and local measures of curvature [K] were calculated. Wilcoxon-signed rank test was used to test the significance of differences of the curvature metrics in eyes with and without staphyloma.
28 eyes from 16 high myopia patients were analyzed. The mean ± SD age was 57 ± 12 years old. 17 eyes had staphyloma (4 only peripapillary) and 11 eyes did not. The axial length between the two groups was statistically different: no staphyloma 27.05 ± 1.05 mm, staphyloma 30.82 ± 2.22 mm (p < 0.0001). All local measures of curvature were different between the two groups: Kmean (no staphyloma 0.11 ± 0.01 mm-1, staphyloma 0.09 ± 0.04 mm-1, p = 0.03), Kstdev (no staphyloma 0.04 ± 0.02 mm-1, staphyloma 0.17 ± 0.15 mm-1, p < 0.0001), Krange (no staphyloma 0.22 ± 0.10 mm-1, staphyloma 1.12 ± 1.12 mm-1, p = 0.0004). However, global measures of curvature (Rc, Q) were not statistically different between the two groups; all eyes in both groups were prolate (Q < 0).
With a commercially available OCT system, we identified loacl curvature differences between highly myopic eyes with and without staphyloma. These initial results are promising for using available OCT systems to identify eyes with and without staphyloma both clinically and for epidemiological studies.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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