China is the country with high incidence of high myopia in the world. High myopia can cause severe vision impairment. So far, there is no effective treatment for high myopia in clinic. Scleral collagen cross-linking surgery has been proven to be effective in preventing animal eye axial elongation in vitro and in vivo. However, the influence of posterior scleral collagen cross-linking on the deformation of the whole eyeball is still unclear. In this study, finite element simulation were used to analyze the changes of eyeball shape and the position of light casting on the retina after posterior sclera cross-linking, and the mathematical algorithm was written to verify their similarity. The results showed that the shape of the whole eyeball was still very similar before and after cross-linking, and the diopter of the eyeball after cross-linking had little change, which had almost no effect on the position of light projection on the retina. Our results indicate that posterior sclera cross-linking wouldn’t lead to distortion to the optometry, that is, the increase of elastic modulus in local scleral tissue after cross-linking wouldn’t cause new problem of optometry and vision.
ObjectiveTo observe and analyze the superficial retinal blood flow density and its related influencing factors in the macular area of adolescents with different types of non-pathological high myopia (HM). MethodsA retrospective clinical study. From March to August 2022, 117 eyes of 117 adolescents who were admitted to Liaocheng Aier Eye Hospital due to myopia were included in the study. According to equivalent spherical degree (SE) and corneal curvature, subjects were divided into mild myopia or emmetropia group (control group), HM group, occult HM (OHM) group, and super HM (SHM) group, with 30 eyes, 28 eyes, 35 eyes, and 24 eyes, respectively. All subjects underwent medical optometry, intraocular pressure, optical coherence tomography (OCT), OCT angiography (OCTA), axial length (AL) and corneal curvature measurements. The diopter was SE. OCTA instrument was used to scan the macular region in the range of 6 mm×6 mm, and the software automatically divided it into three concentric circles centered on the fovea of the macular, namely, the central area with a diameter of 1 mm, the inner ring area with a diameter of 1-3 mm, and the outer ring area with a diameter of 3-6 mm. The superficial retinal vascular density (SRVD), vascular perfusion density (SBPD), the area, perimeter (PERIM), avascular index (AI) of foveal avascular area (FAZ) and retinal thickness were measured in the macular region as a whole and in different regions. One-way analysis of variance was used to compare the data among groups, and the least significant difference t-test was used to compare the data among groups. The correlation of AL, corneal curvature and intraocular pressure with SRVD and SBPD in macula was analyzed by Pearson correlation analysis. ResultsThere were significant differences in SRVD and SBPD in the central, inner and outer regions of macula in control group, HM group, OHM group and SHM group (P＜0.05). There were statistically significant differences in the thickness of the retina above, below and on the temporal side of the central and outer ring regions (P＜0.05). However, no statistically significant difference was in the thickness of the retina on the nasal side (P＞0.05). There was no significant difference in PERIM (P＞0.05). There were significant differences in FAZ area and AI (P＜0.05). Correlation analysis showed that AL was negatively correlated with SRVD and SBPD in macular whole and central, inner and outer ring regions (P＜0.05). Corneal curvature and SE were positively correlated with the SRVD and SBPD of macular whole, central area and outer ring area (P＜0.05). AL was negatively correlated with retinal thickness in the outer ring region (P＜0.05). SE was positively correlated with the thickness of the retina above, below and temporally in the outer ring region (P＜0.05). AL was negatively correlated with FAZ area and AI (P＜0.05). SE was positively correlated with FAZ area and PERIM (P＜0.05). Retinal thickness was positively correlated with SRVD and SBPD (P＜0.05). ConclusionsThe SRVD and SBPD of different types of HM in adolescents decreases to different degrees. The thickness of the retina in the central region is thicker, and the retina in the outer ring region is thinner. With the decrease of SRVD, the retinal thickness gradually is thinner.