RT Journal Article
A1 Dai, Yining
A1 Zhang, Qinqin
A1 Zhou, Hao
A1 Chu, Zhongdi
A1 Zhou, Xiao
A1 Wang, Ruikang
T1 Impacts of Axial Length on Retinal and Choriocapillaris Blood Flow Quantification in Myopia with Swept-Source Optical Coherence Tomography Angiography
JF Investigative Ophthalmology & Visual Science
JO Invest. Ophthalmol. Vis. Sci.
YR 2020
VO 61
IS 9
SP PB0017
OP PB0017
SN 1552-5783
AB    To evaluate the impact of image magnification correction on retinal and choriocapillaris (CC) blood flow quantification using swept-source optical coherence tomography angiography (OCTA) in myopic eyes.    Subjects with myopia were recruited for ocular biometry, refraction, and OCTA imaging with a 6 × 6-mm protocol. The retinal vascular area density (RVAD), retinal vascular skeleton density (RVSD), retinal flow impairment area (RFIA), percentage of CC flow deficits (FD%), and the mean size of CC flow deficits (FDs) were quantified within a 5-mm-diameter circle centered on the fovea before and after magnification correction using the Littman and the modified Bennett formulae.    Forty eyes from 20 subjects were enrolled in the study. The median (range) age of the subjects was 45 (25 to 71) years. The mean (range) spherical equivalent refractive error was -11.11 (-0.75 to -23.75) diopters and mean (range) axial length was 29.53 (24.67 to 34.42) mm. Images from 14 eyes were excluded due to poor image quality leaving 26 for analysis. The corrected RFIA was significantly greater than the uncorrected RFIA (3.78 mm2 vs. 1.62 mm2, P<0.0001). The corrected mean size of CC FDs was significantly greater than the uncorrected measurement (3754.4 µm2 vs. 2851.9 µm2, P<0.0001). However, the corrected RVAD and RVSD were significantly lower than those uncorrected measurements (0.48 vs. 0.50, P<0.0001 and 0.12 vs. 0.14, P<0.0001, respectively). No significant difference was observed in the CC FD% before and after magnification correction (15.92%vs. 16.91%, P=0.2336).    Ocular magnification effects should be taken into account when comparing the interocular lateral measurements derived from OCTA in myopic eyes.  This is a 2020 Imaging in the Eye Conference abstract.     Representative illustration of the retinal and CC flow images before (A-G) and after (H-N) magnification correction in a myopic eye. A and H: En face retinal blood flow images. B and I: Corresponding RFIA maps. C and J: Corresponding RVSD maps. D and K: Corresponding RVAD maps. E and L: En face CC flow images. F and M: Corresponding CC FDs (green color) overlaid onto the CC flow images. G and N: CC FD binary maps for quantification. Analyses were performed within a 5-mm-diameter circle (yellow) centered on the fovea. Images are from the left eye of a 39-year-old subject with an axial length of 30.75 mm. All images are 6×6-mm fields.      
RD 6/16/2021