Subfoveal Choroidal Thinning May Cause Ocular Elongation in Young Adults with Myopia

In patients with myopia between the ages of 18 and 24 years, choriocapillaris (CC) perfusion area is not associated with spherical equivalent refraction (SER) and axial length (AL), while AL and retinal thickness (RT) are negatively correlated with the area of the foveal avascular zone (FAZ), researchers found in a study published in Microvascular Research. Subfoveal choroidal thickness (SFCT) thinning may be secondary to ocular elongation, and CC perfusion area may be an independent factor, the investigators said.

Previous studies have reported changes in blood flow in pediatric and older adult patients with myopia, but there has been limited research on the changes of CC perfusion area and the FAZ area in young adults.

The researchers recruited study participants in 2019 from 2 classes of senior undergraduates of a Chinese medical school. The participants had best-corrected visual acuity (BCVA) of at least 16/20, intraocular pressure lower than 21 mm HG, and no sign of pathological myopia, history of intraocular surgery, or ocular or systemic diseases that could impact the ocular circulation. The researchers instructed them to stop any consumption of alcohol, caffeine, and nicotine at least 12 hours before the study.

The study included 148 healthy eyes from 77 adults with myopia (48 women) with a mean age of 21.8±1.32 years. The investigators procured optical coherence tomography angiography (OCT-A) scans and used automated segmentation lines to divide the capillary bed into the superficial, deep layers and CC perfusion area.

Mean SER was -4.06±2.26 D, mean AL was 25.25±1.28 mm, and FAZ area was 0.31±0.10 mm². Mean SFCT was 232.16±56.65 μm, and mean CC perfusion area was 2.17±0.10 mm².

SER was negatively correlated with RT in the fovea region (r=-0.180, P =.028) and positively correlated with the RT in the nasal (r=0.224, P =.006) and inferior (r=0.217, P =.008) regions. SER was significantly associated with the deep vessel density (DVD) of the retinain the fovea region (r=-0.185, P =.025) and positively correlated with SFCT (r=0.486, P <.001).

AL was strongly associated with the RT in the fovea region (r=0.250, P =.002), negatively correlated with FAZ area (r=-0.232, P =.005), and positively correlated with the retinal DVD (r=0.284, P <.001) in the fovea.

CC perfusion area did not significantly correlate with SER and AL.

Limitations of the study include small sample size and the lack of ocular magnification correction during image analyses.

Reference

Xiuyan Z, Qingmei T, Qiuxin W, et al. Thickness, vessel density of retina and choroid on OCTA in young adults (18–24 years old). Microvascular Research. Published online April 9, 2021. doi:10.1016/j.mvr.2021.104169