Choroidal vascularity index in adults with different refractive status

We aimed to perform structural analysis of the choroid in adults with different refractive status.

A prospective, comparative study of 100 right eyes of 100 patients ages 18-40 years was conducted. The patients were divided into four groups according to spherical equivalent (SE): Group 1: -0.5 and above, low-to-moderate myopia; Group 2: -6 and above, high myopia; Group 3: +0.5 and above, hyperopia; Group 4: +/- 0.5, emmetropia. With the images obtained using enhanced depth imaging optical coherence tomography (EDI-OCT), the total choroidal area (TCA), luminal area (LA), stromal area (SA), and choroidal vascular index (CVI) were calculated using the binarization method. The anterior chamber depth (ACD), axial length (AL), and central corneal thickness (CCT) values were measured by optical biometry. All parameters were compared between groups. The correlation of biometric parameters with CVI was examined.

Parameters were found to be statistically different between the four groups. TCA, LA, and SA values were the highest in Group 3 and lowest in Group 2. L/S ratio and CVI values in Group 3 were significantly lower than in the other groups. There was a negative correlation between AL with SE and CT, and no correlation between the CVI and other parameters.

CVI decreases when emmetropization is disrupted and changes to hypermetropia or myopia. The reason for the decrease in myopia is the reduction of the luminal area, while in hyperopia it is due to an increase in the stromal area. When there is a shift toward myopia, there is a decrease in the TCA, but the CVI does not change significantly. Unlike CT, the CVI is not affected by factors such as SE and AL; therefore, the CVI can be a useful parameter for examining choroidal changes in refractive errors.