Objective:To investigate the changes in retinal structure and microcirculation in the patients with high myopia(HM)and the non-HM individuals,and to elucidate the correlations between axial length(AL)and the related parameters.Methods:A total of 80 eyes from 40 patients with simple HM(non-pathological myopia)were enrolled as case group,while 80 eyes from 40 age-and sex-matched non-HM subjects were selected as control group.The best-corrected visual acuity(BCVA),AL,spherical equivalent(SE),and optical coherence tomography angiography(OCT A)examination were performed in all the subjects.OCTA examination was used to measure the vascular density of the superficial retinal capillary plexus(SCP),deep retinal capillary plexus(DCP),and radial peripapillary capillary(RPC),as well as central macular thickness(CMT),and the area and volume of the foveal avascular zone(FAZ)of the subjects in two groups.The differences in these parameters of the subjects between two groups were analyzed.The AL of the subjects in two groups was measured using a biometer,and its correlations with the parameters mentioned above were evaluated.Results:No statistically significant differences were observed in age or sex distribution between two groups(P＞0.05).Compared with control group,both SCP and DCP vessel densities acrossing the whole(excluding the foveal),parafoveal,and perifoveal regions of the macular retina of the patients in case group were significantly decreased(P＜0.05).Compared with control group,the RPC vessel densities in the optic disc region of the patients in case group were significantly decreased in the whole,peripapillary,peripapillary superior,and peripapillary inferior sectors(P＜0.001),while the RPC vessel density was increased inside the disc(P＜0.01).Compared with control group,the whole FAZ volume of the patients in case group was increased(P＜0.01),while the parafoveal and perifoveal CMT were decreased(P＜0.001).In case group,AL was negatively correlated with SCP vessel density(r=-0.642,P＜0.001),DCP vessel density(r=-0.388,P＜0.001),RPC vessel density(r=-0.639,P＜0.001),and CMT(r=-0.495,P＜0.001),but positively correlated with FAZ volume(r=0.580,P＜0.001);no significant correlation was found between AL and FAZ area(r=-0.062,P=0.587).Conclusion:The patients with HM may exhibit early reductions in SCP,DCP,and RPC vessel densities,thinning of the central retina,and increased FAZ volume.Furthermore,as AL increases,SCP,DCP,and RPC vessel densitiesas as well as CMT decreases,while FAZ volume increases,suggesting significant associations between AL and the parameters mentioned above.

Objective:To observe the clinical efficacy of pars plana vitrectomy (PPV) combined with dexamethasone intravitreal implant (DEX) in the treatment of proliferative diabetic retinopathy (PDR).Methods:A prospective randomized controlled study. A total of 57 PDR patients with 79 eyes diagnosed by Department of Ophthalmology of The First Affiliated Hospital of Nanjing Medical University from May 2021 to February 2023 were included in the study. Best corrected visual acuity (BCVA) and optical coherence tomography (OCT) were performed in all affected eyes. Central macular thickness (CMT) was measured by OCT. The patients were randomly divided into control group and experimental group, with 27 cases and 35 eyes and 30 cases and 44 eyes, respectively. All eyes were treated with routine 25G PPV and intraoperative whole- retina laser photocoagulation. At the end of the operation, the experimental group was given 0.7 mg DEX intravitreal injection. At 1, 4, 12, and 24 weeks after operation, the same equipment and methods were used for relevant examinations. The improvement after surgery was assessed according to the diabetic retinopathy severity score (DRSS). Mixed analysis of variance was used to compare logarithm of the minimum angle of resolution BCVA and CMT between the two groups and within the two groups before and after operation.Results:At 1, 4, 12 and 24 weeks after surgery, BCVA was significantly improved at different time points after surgery, and the differences were statistically significant ( P<0.001). At different time after operation, BCVA and CMT in experimental groups were significantly better than that in control group, with statistical significance ( P<0.05). Compared with the CMT before surgery, the CMT at all time point after surgery in experimental group were significantly decreased, and the difference were statistically significant ( P<0.05). There was no significant difference one week after eye operation in control group ( P=0.315). At 4, 12 and 24 weeks after operation, CMT decreased in control group, and the differences were statistically significant ( P<0.05). Compared with before surgery, DRSS increased two steps higher at 1, 4, 12 and 24 weeks after surgery in 20 (45.45%, 20/44), 26 (59.10%, 26/44), 32 (72.73%, 32/44) and 31 (70.45%, 31/44) eyes in the experimental groups, respectively. The control group consisted of 15 (42.86%, 15/35), 15 (42.86%, 15/35), 16 (45.71%, 16/35) and 18 (51.43%, 18/35) eyes, respectively. There was no significant difference in DRSS at 1, 4 and 24 weeks after operation between the control group and the experimental group ( P=0.817, 0.178, 0.105). At 12 weeks after surgery, the difference was statistically significant ( P=0.020). Conclusion:PPV combined with intravitreal injection of DEX in the treatment of PDR can improve postoperative visual acuity, alleviate postoperative macular edema and improve the severity of DR.