Magnification Effect of Foveal Avascular Zone Measurement Using Optical Coherence Tomography Angiography

Mika Suda; Yuji Yoshikawa; Gaku Terauchi; Soiti Matsumoto; Takuhei Shoji; Kei Shinoda; Atsushi Mizota; Yoshiharu Kobayashi

doi:10.1159/000507501

Magnification Effect of Foveal Avascular Zone Measurement Using Optical Coherence Tomography Angiography

Biomed Hub. 2020 Jun 12;5(2):79-86. doi: 10.1159/000507501. eCollection 2020 May-Aug.

Authors

Mika Suda¹, Yuji Yoshikawa², Gaku Terauchi³, Soiti Matsumoto³, Takuhei Shoji², Kei Shinoda², Atsushi Mizota³, Yoshiharu Kobayashi¹

Affiliations

¹ Department of Orthoptics, Teikyo University Faculty of Medical Technology, Tokyo, Japan.
² Department of Ophthalmology, Saitama Medical University, Saitama, Japan.
³ Department of Ophthalmology, Teikyo University School of Medicine, Tokyo, Japan.

Abstract

Purpose: The aim of this study was to evaluate the foveal avascular zone (FAZ) of healthy subjects and examine the magnification effect.

Methods: A total of 33 healthy volunteers were enrolled and all subjects were eligible for analysis. Optical coherence tomography angiography (OCTA) examination scanned 3 × 3 mm of the macular area. The FAZ area was measured on the superficial OCTA en face image with and without correction by axial length. The relationship between changes in the FAZ area after correction with the axial length was examined.

Results: The mean age was 21.9 ± 0.6 years. The mean axial length was 24.87 ± 1.17 mm and mean spherical equivalent (SE) value was -3.64 ± 2.83 diopters (D). The FAZ area was 0.26 ± 0.10 mm² before the axial length correction and 0.27 ± 0.10 mm² after the correction. In the eyes that had an axial length longer than or equal to 26 mm or SE less than or equal to -6 D, the FAZ area after correction was significantly larger than that before correction (p < 0.01). The change of FAZ area after correction with axial length was significantly correlated with the axial length (R ² = 0.88, p < 0.01) or SE value (R ² = 0.55, p < 0.01).

Conclusion: FAZ areas were comparable to previous reports. In high myopic cases, the magnification effect needs to be considered when evaluating the FAZ area.

Keywords: Axial length; Foveal avascular zone; Magnification effect; Myopia; Optical coherence tomography angiography.