Quantitative changes in iris vasculature and blood flow in patients with different refractive errors

Purpose To evaluate the association between microvascular changes in the iris and refractive errors. Methods A cross-sectional case study. Seventy eyes from 70 patients with refractive errors were enrolled. Iris microvasculature was analyzed using optical coherence tomography angiography (OCTA). We divided the iris images into three regions and calculated the vessel area density (VAD) and vessel skeleton density (VSD) of the inner one-third, inner two-thirds, and the entirety of the iris. Results The VADs and VSDs of the different regions were significantly different. The VAD and VSD of the inner one-third of the iris were higher than those of the other regions. The iris blood vessels were denser near the pupil margin, and blood vessels from the iris root to the pupil edge were radially distributed. The VAD and VSD of patients with mild hyperopia and emmetropia were higher than those of patients with moderate and high myopia. As the spherical equivalent increased, the VAD and VSD of the iris increased. Neither age nor sex contributed to significant differences in VAD and VSD. Conclusion Quantitative changes in iris microvasculature may indicate the development of myopia.