July 2018
Volume 59, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2018
The Repeatability of Superficial Retinal Vessel Density Measurements in Eyes with Long Axial Length Using Optical Coherence Tomography Angiography
Author Affiliations & Notes
  • Mengyang Li
    Department of Ophthalmology, Peking University People's Hospital, Beijing, China
  • Chuan Zhang
    Department of Ophthalmology, Peking University People's Hospital, Beijing, China
  • Mingwei Zhao
    Department of Ophthalmology, Peking University People's Hospital, Beijing, China
  • Jinfeng Qu
    Department of Ophthalmology, Peking University People's Hospital, Beijing, China
  • Footnotes
    Commercial Relationships   Mengyang Li, None; Chuan Zhang, None; Mingwei Zhao, None; Jinfeng Qu, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science July 2018, Vol.59, 2871. doi:
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      Mengyang Li, Chuan Zhang, Mingwei Zhao, Jinfeng Qu; The Repeatability of Superficial Retinal Vessel Density Measurements in Eyes with Long Axial Length Using Optical Coherence Tomography Angiography. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2871.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : To determine whether the optical coherence tomography angiography (OCTA) repeatability is affected by axial length (AL) in healthy young adults with myopia.

Methods : This cross-sectional observational study enrolled 22 healthy volunteers from May 1 to September 30, 2017. All of the subjects underwent OCTA, AL and refractive diopter measurements. Vessel length density (VLD), perfusion density (PD), and fovea avascular zone (FAZ) area of the superficial retinal vessel were evaluated. Repeatability was assessed by intraclass correlation coefficient (ICC) and Bland-Altman analysis. Pearson r correlation was used to analyze the relation of AL and the absolute difference between two serial measurements.

Results : A total of 22 subjects (9 males and 13 females; mean [SD] age, 26 [3] age) were enrolled in this study. Four eyes were unable to obtain qualified images and 40 eyes were analyzed. The 3×3 mm scan pattern showed a good repeatability with all ICCs over 0.7, particularly in the short AL group (0.91[95% CI, 0.80-0.96] for VLD, 0.90[95% CI, 0.80-0.96] for PD and 0.96[95% CI, 0.91-0.98] for FAZ). However, the VLD and PD varied with a quite large range in the 6×6 mm scan pattern, particularly in the 6×6 inner ring for the long AL group (0.43[95% CI, -0.10-0.77] for VLD and 0.45[95% CI, -0.07-0.78] for PD) and outer ring (0.35[95% CI, -0.19-0.73] for VLD and 0.35[95% CI, -0.19-0.73] for PD). For all scan patterns, the ICCs of the short AL group were distinctly higher than those of the long AL group. Bland-altman analysis presented good repeatability of 3×3mm scan, while 6×6 mm scan showed larger limit agreements. The correlation between AL and absolute difference of two measurements showed significant positive correlations between ALs and VLD of the 6×6 mm inner (r2=0.12, p= 0.0016) and outer rings (r2=0.23, p= 0.0282).

Conclusions : The elongation of axial length lowered the OCTA repeatability, and the 6×6 mm scan pattern was affected more. Therefore, we recommend the 3×3 mm scan as the preferred choice to obtain reliable quantitative analysis of the macular area in axial myopic eyes. We also advise caution when adapting images from long AL subjects for quantitative analysis, particularly in the 6×6 mm scan pattern.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Table 1. ICC of VLD, PD and FAZ in two groups.

Table 1. ICC of VLD, PD and FAZ in two groups.

 

Figure 1. Relationship between AL and absolute difference in PD, VLD and FAZ area.

Figure 1. Relationship between AL and absolute difference in PD, VLD and FAZ area.

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