Choroidal thickness and choriocapillaris vascular density in myopic anisometropia

Abstract

Background This study aims to examine interocular differences in the choroidal thickness and vascular density of the choriocapillaris in anisometropic myopes and to further explore the relationship between choroidal blood flow and myopia. Methods The sample comprised 44 participants with anisometropic myopia, aged 9 to 18 years, with normal best-corrected visual acuity. All participants underwent a series of examinations, including spherical equivalent refraction (SER) and axial length (AL), measured by a Lenstar optical biometer and optical coherence tomography angiography (OCTA) scanner. OCT measured the choroidal thickness, vascular density, and flow voids of the choriocapillaris, and a customized algorithm was implemented in MATLAB R2017a with the post-correction of AL. The choroidal thickness was measured at the fovea and 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mm nasally, temporally, inferiorly, and superiorly to the fovea. The vascular density and the flow voids of the choriocapillaris were measured at a 0.6-mm-diameter central circle, and the 0.6–2.5 mm diameter circle in the nasal, temporal, inferior, and superior regions. Repeated-measured ANOVAs were used to analyze the interocular differences. Partial correlations with the K value and age adjustments were used to study the relationships between the choroidal thickness, the choriocapillaris vascular density and flow voids, the SER and AL. Results The choroidal thickness of the more myopic eyes was significantly thinner than less myopic eyes (P ≤ 0.001), and the flow voids in the more myopic eyes were more than less myopic eyes (P = 0.002). There was no significant difference in the vascular density of the choriocapillaris between the more and less myopic eyes (P = 0.525). However, when anisometropia was more than 1.50 D, the vascular density of choriocapillaris in the more myopic eyes was significantly less than the less myopic eyes (P = 0.026). The interocular difference of the choroidal thickness was significantly correlated with the interocular difference in SER and AL in the center, superior, and inferior regions but not in the nasal or temporal regions. The interocular differences of the vascular density and the flow voids of the choriocapillaris were not correlated with the interocular difference of SER and AL. Conclusions The choroidal thickness is thinner in the more myopic eyes. The flow void is increased, and the vascular density of the choriocapillaris is reduced in the more myopic eyes of children with anisometropia exceeding 1.50 D.

Choroidal Vascular Density Quantification in High Myopia with or without Choroidal Neovascularization Using Optical Coherence Tomography Angiography

“…Vincent et al [19] examined the choroidal thickness in a sample of myopic anisometropia and found the choroidal thickness was signifcantly thinner in the more myopic eyes. Liu et al [20] found that choroidal thickness was thinner in anisometropic myopic eyes. Te choroid is a highly vascularized tissue consisting of the choriocapillaris and medium-and large-vessel layers.…”

Superficial Retinal Vessel Density and Foveal Avascular Zone in Myopic Anisometropia: An OCTA-Based Study in Young Chinese Children

“…Furthermore, the decrease in SRVLD was significantly correlated with AL in high myopia [ 7 , 17 , 18 ]. We believe that the choroidal thickness is thinner in the more myopic eyes, and the vascular density of the choriocapillaris is reduced in the more myopic eyes of children with anisometropia, which also may lead to a thinner retina [ 19 – 21 ]. The findings reported in all the studies were consistent with our result in patients with an interocular difference of ≤1.5 D in SER but were in contrast with our result in patients with an interocular difference of >1.5 D in SER.…”

“…It is well known that retinal and choroidal thickness is thinner in the more myopic eyes. The vascular density of the choriocapillaris is reduced in the more myopic eyes of children with anisometropia [ 19 , 21 , 29 ]. Additionally, we speculate that this may be due to the lag of accommodation.…”

“…The dominant eye has a greater degree of myopia [ 27 , 28 ] and thus gains a hyperopic defocus due to the greater lag of accommodation [ 30 ]. As a consequence, choroidal thickness decreases [ 19 , 21 , 31 , 32 ], which may lead to a thinner retina and a decreased SRVLD [ 33 ]. Therefore, we have considered that a greater degree of myopia (a longer axial length) in the dominant eye may lead to a thinner retina and a decreased SRVLD [ 33 ] in all the patients with myopic anisometropia, although the difference was not statistically significant in the patients with an interocular difference of >1.5 D. Studies of over 10,000 patients also found that in myopic anisometropia, the dominant eye is typically the eye with the lower refractive error [ 34 , 35 ].…”

Multiple Factors Causing Myopia and the Possible Treatments: A Mini Review

“…They also reported that neither procedure affected the protein of suprachoroidal fluid in their contralateral eyes as controls ( 23 ). The altered levels of protein and marker dye in both myopic and recovering eyes suggest that choroidal circulation dynamics and capillary permeability are markedly altered ( 24 ).…”