Repeatability of Manual Measurement of Foveal Avascular Zone Area in Optical Coherence Tomography Angiography Images in High Myopia

Abstract

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses /by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 113 Original ArticleHigh myopia is one of the most common causes of visual loss and is especially common in Asia. The prevalence of myopia is as high as 80% in Asia and 25% in other regions [1][2][3]. Severe myopia can increase the risk of glaucoma, retinal detachment, chorioretinal atrophy, and lacquer cracks. Therefore, high myopia patients, even those without other ophthalmic diseases, should not be overlooked [4]. In myopia, the sclera and chorioretina are enlarged to reduce the thickness of the macular choroid, which may result in delayed choroidal circulation to induce an ischemic state of Purpose: To analyze the repeatability of manual measurement of foveal avascular zone (FAZ) area in an optical coherence tomography angiography (OCTA) image in high myopia. Methods: This study comprised patients with high myopia and controls. Two consecutive FAZ areas of the superficial and deep capillary plexus were obtained using OCTA. The intraclass correlation coefficient (ICC) and coefficient of variation (CV) were assessed, and univariate and multivariate generalized linear mixed models were conducted to identify factors related to repeatability. Results: Thirty eyes with high myopia and 34 eyes of healthy subjects were included in the study. The mean age in high myopia and control subjects was 55.5 and 60.8 years, respectively, the mean spherical equivalent was -9.98 and -0.55 diopters, and the mean axial length was 28.0 and 23.9 mm. The ICCs of FAZ area of the superficial capillary plexus (SCP) were 0.891 and 0.919, while the CVs were 8.8% and 8.5%. In measurement of the deep capillary plexus, the ICCs were 0.788 and 0.907, while the CVs were 11.2% and 11.0%, which were acceptable but exhibited lower repeatability than those of SCP. Multivariate analyses showed that older age (p = 0.030) and greater axial length (p = 0.005) were significantly associated with lower repeatability of SCP FAZ area measurements. In addition, greater axial length (p = 0.044) was a significant factor for lower repeatability of deep capillary plexus FAZ area measurements. Conclusions: Manual measurement of FAZ area using OCTA exhibited relatively good repeatability for high myopia. Age and axial length affected repeatability and should be considered when analyzing FAZ areas in high myopia patients.

Normative Vascular Features on OCT Angiography in Healthy Nepalese Eyes

“…This biological association between FAZ parameters and refractive has already been reported in various studies. 17–20 Although we have made corrections for AL-related magnification to take account of FAZ parameters, these variations alone may not have been the effect of biological associations.…”

“…This biological association between FAZ parameters and refractive has already been reported in various studies. [17][18][19][20] Although we have made corrections for AL-related magnification to take account of FAZ parameters, these variations alone may not have been the effect of biological associations. In our study, the mean SFCT was 309.47 ± 68.39 μm (Range: 192 to 417 μm) and 308.31 ± 69.36 (Range: 196 to 420 μm), respectively, in right eye and left eye with a mean SFCT between two eyes of 308.89 ± 68.87 μm.…”

Repeatability of Optical Coherence Tomography Angiography Measurements in Patients with Retinal Vein Occlusion

“…Fang et al [ 17 ] reported that FAZ area measurements using OCTA exhibited excellent repeatability and correlation in healthy eyes and that the ICC associated with FAZ area measurements was 0.961. Lee et al [ 18 ] reported that the repeatability of manual FAZ area measurements was good in high myopia patients. The ICC associated with the SFAZ area measurements was 0.891 and the CV was 8.8%, and those associated with the DFAZ were 0.788 and 11.2%, respectively.…”

Application of Angio Optical Coherence Tomography and Flash Electroretinogram in the Study of Retinal Morphology and Function in High Myopia

“…However, the results of research into the patterns and mechanisms of FAZ area changes in high myopia are inconclusive [6] . During the process of high myopic axial lengthening, the eyeballs do not uniformly expand to maintain the spherical shape [22]; the difference in the length of the high myopia axis leads to different degrees of optical magni cation, and current OCTA equipment does not provide correction methods [23]. This may affect the accuracy of the FAZ area of highly myopic eyes, resulting in discrepancies.…”

“…The inner layer of the retina is mainly composed of the nerve ber layer and the ganglion cell layer. The OP wave [22] mainly re ects the condition of the microcirculation of the retinal inner layer. As the degree of myopia increases, the blood ow density of the super cial microcirculation decreases, the OP wave amplitude is reduced, and the function of the inner retina is weakened.…”