ObjectiveTo observe the changes in the fundus microcirculation after implantation of the implantable Collamer lens (ICL) in eyes with moderate to high myopia. MethodsA retrospective study. From February 2022 to October 2023, 65 patients (100 eyes) with moderate to high myopia who underwent ICL implantation at the Refractive Surgery Center of the General Hospital of Central Theater Command of the Chinese People's Liberation Army were included in the study. According to the spherical equivalent (SE), they were divided into 3 groups: moderate myopia group (?6.0 D≤SE＜?3.0 D), high myopia group (?9.0 D≤SE＜?6.0 D), and ultra-high myopia group (SE＜?9.0D), comprising 33, 35, and 32 eyes, respectively. All underwent swept-source optical coherence tomography angiography (SS-OCTA) examination. SS-OCTA was used to scan a 3 mm×3 mm area of the macula to measure the preoperative and 6-month postoperative flow density in the superficial capillary plexus (SCP), deep capillary plexus (DCP), choriocapillaris, and choroidal vascular layer, as well as the area, perimeter (PERIM), and acircularity index (AI) of the foveal avascular zone (FAZ), and the retinal and choroid thicknesses. The choroid within 3 mm of the fovea was divided into two concentric circles centered on the fovea: the foveal zone (diameter 1 mm) and the parafoveal zone (1-3 mm), totaling five zones. The parafoveal zone was further divided into four quadrants: superior, inferior, nasal, and temporal. The changes in blood flow density and FAZ parameters in the macular area before and after the surgery were compared. The paired t test was used for the comparison of each index. ResultsSix months after the surgery, compared with before the surgery, there was no statistically significant difference in the blood flow density among the three groups of affected eyes in terms of SCP, DCP and choriocapillaris blood flow density (P＞0.05); in the choroidal layer, the nasal side difference in the high myopia group was statistically significant (P=0.044), and the central foveal area and nasal side differences in the ultra-high myopia group were also statistically significant (P=0.003, 0.037). In terms of retinal thickness, the lower and temporal side differences in the moderate myopia group were statistically significant (P＜0.05); the differences in all regions of the high myopia group were not statistically significant (P＞0.05); the upper, nasal, lower and temporal side differences in the ultra-high myopia group were all statistically significant (P＜0.05). In terms of choroidal thickness, the central foveal area and nasal side differences in the moderate myopia group and the ultra-high myopia group were statistically significant (P＜0.05); the differences in all regions of the high myopia group were not statistically significant (P＞0.05). There was no statistically significant difference in FAZ area, PERIM and AI among the three groups of affected eyes (P＞0.05). ConclusionsSix months after ICL implantation surgery, there are no significant effects on SCP, DCP, choriocapillaris blood flow density, FAZ area, PERIM, and AI of the eyes with moderate to high myopia. The overall retinal thickness showed an increasing trend after the surgery. The changes in choroidal thickness and choroidal layer blood flow density in patients with different refractive errors are not synchronous. Therefore, the changes in blood flow and thickness of the foveal area and nasal choroid should be particularly focused on after the surgery.
