The Niblack binarization method can be used to analyze the luminal area of choroid in an OCT image with good repeatability and reproducibility. The change in the subfoveal choroidal area after PDT is due mainly to a decrease in the luminal areas.

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In normal adult eyes, there was good reproducibility and repeatability of SFCT measurements obtained by the SD-OCT and SS-OCT instruments. However, the choroid measured with DRI-SS-OCT was thicker than that measured with both SD-OCT instruments, and, thus, the choroidal thickness should not be compared between the SD-OCT and SS-OCT instruments. (www.umin.ac.jp/ctr number, UMIN000011259.).

This study was conducted to investigate the size and shape of the foveal avascular zone (FAZ) determined by optical coherence tomography angiography (OCTA) and the relationship of the size and shape to the clinical findings in normal subjects. This was a cross-sectional study with seventy eyes of 70 volunteers. The size of the superficial FAZs were assessed by its area, length of perimeter, and Feret’s diameter, and the shape by the circularity, axial ratio, roundness, and solidity. The correlations between each parameter and the clinical findings were statistically determined. The coefficients of variation (CV) of the parameters of FAZ size were higher than that of the parameters of FAZ shape. The refractive error and axial length were significantly correlated with area-related factors. The central macular thickness (CMT) was significantly correlated with all parameters. Although the CMT was a critical factor that was significantly correlated with the size and shape characteristics of the FAZ, the shape might be a better factor for characterizing the FAZ than the size because of the low CV of shape-related factors and the characteristics are less affected by the other ocular factors.

No abstract