The choroid vascular index and its association with visual acuity in children and young adults with high myopia

To explore the relationship between the choroid vascular index (CVI) and best corrected visual acuity (BCVA) in a young population with high myopia (HM).

Three hundred twenty-six patients with HM were recruited. All subjects underwent a comprehensive ophthalmic examination and enhanced depth imaging optical coherence tomography (EDI-OCT). The horizontal and vertical subfoveal choroidal areas within a 3-mm diameter centred over the fovea were selected. Choroid thickness (ChT), horizontal and vertical total choroidal area (TCA_H and TCA_V), luminal area (LA_H and LA_V) and stromal area (SA_H and SA_V) within the 3-mm diameter were assessed. CVI values (CVI_H and CVI_V), defined as the ratio of LA to TCA, were also calculated. The correlations among choroid parameters and ocular characteristics were analysed.

The median age, spherical equivalent (SE) and BCVA were 22.4 years, -10.1 dioptres and 0.099 logMAR, respectively. The ChT was thickest on the temporal and superior sides of the macula and thinnest in the nasal region, with a significant difference. The value of CVI_H was significantly greater than that of CVI_V because SCA_H was smaller than SCA_V. Both CVI_H and CVI_V were closely correlated with BCVA in all patients.

The CVI is significantly related to BCVA but is not affected by age, axial length or SE, suggesting that the CVI could be used as an adjunct tool for assessing the visual acuity status in patients with HM.