ObjectiveTo observe the differences in the positive rate of conjunctival sac microbial culture after different methods of preventing infection before intravitreal injection (IVI). MethodsA prospective case-control study. A total of 1 200 participants with fundus diseases who received IVI injection at Tianjin Medical University Eye Hospital from July 2021 to December 2023 were included. Patients were randomly divided into 6 groups according to eye spot with antibiotic solution 3, 1 and 0 days before IVI and local eye disinfection with povidone-iodine (PVI) 3 min and 30 s before IVI: the first 3 days of antibiotics+3 min PVI group, the first 1 day of antibiotics+3 min PVI group, the first 0 days of antibiotics+3 min PVI group, the first 3 days of antibiotics+30 s PVI group, the first 1 day of antibiotics+30 s PVI group, the first 0 days of antibiotics+30 s PVI group, there were 200 cases in each group. Microbial sampling and cultivation of conjunctival sac were conducted before IVI to compare the differences in positive rates among different groups. Multiple group comparisons were conducted using one-way analysis of variance; The comparison of count data is conducted using χ2 test. ResultsAmong the 1 200 patients, there were 566 males and 634 females. Age (62.59±13.44) years old. There were 397 cases of diabetes and 482 cases of hypertension. IVI frequency (2.35±2.34). 64 cases were positive for conjunctival sac culture before IVI. The age (F=1.468), sex composition ratio (χ2=2.876), diabetes (χ2=10.002), hypertension (χ2=6.019), times of IVI (χ2=4.507), and positive rate of conjunctival sac bacterial culture (χ2=6.272) of patients in each group had no statistical significance (P＞0.05). Using the duration of antibiotic application before IVI as a stratified factor, there was no statistically significant difference in the positive rate of conjunctival sac culture between groups with different durations of antibiotic application before IVI [χ2=0.414, P=0.52, combined odds ratio (OR)=0.819, 95% confidence interval (CI) 0.493-1.360]. Using the duration of PVI application as a stratified factor, there was no statistically significant difference in the positive rate of conjunctival sac culture between different PVI disinfection times [χ2=0.000, P=1.00, combined OR=1.00, 95% CI 0.503-1.988]. ConclusionsPre IVI treatment with 0.5% PVI for 30 s can inhibit the growth of microbial colonies in the conjunctival sac. The application of local antibiotic eye fluid in the anterior eye of IVI cannot reduce the positive rate of conjunctival sac bacteria.
ObjectiveTo observe the effects of exosomes derived from rat mesenchymal stem cells (MSC-exosomes) on the rat experimental autoimmune uveitis (EAU) model.MethodsTwelve Lewis rats were randomly divided into experimental group and control group by random number table, with 6 rats in each group. Rats in the experimental group were established with EAU model, 100 μl of MSC-exosomes (50 μg) were periocular injected on the 9th day after modeling while the control rats were injected with the same volume of phosphate buffer. At different time points after modeling, the retinal structure was observed by hematoxylin and eosin (HE) staining, and the clinical and pathological manifestations were evaluated. T cells from the two groups were analyzed by flow cytometry. Immunohistochemical staining was used to observe the expression of macrophage surface marker CD68. The effect of MSC-exosomes on T cells was measured by lymphocyte proliferation assays. And flow cytometry was used to detect Th1, Th17 and regulatory T cells Variety. Electroretinogram (ERG) was used to evaluate the retinal function. Data were compared between the two groups using the t test.ResultsHE staining showed that the retina structure of the experimental group was more complete than that of the control group on the 15th day after modeling. Immunohistochemical staining showed that the positive expression of CD68 in the experimental group was significantly less than that in the control group. On the 15th day after modeling, the retinal pathological score of the experimental group was lower than that of the control group. On the 9th to 13th day after modeling, compared to the control group, the average clinical scores of the retina in the experimental group were lower, and the difference was statistically significant (t=3.665, 3.21, 3.181, 4.121, 3.227; P＜0.01). The results of T cell proliferation assay showed that exosomes (1.0, 10.0 μg/ml) inhibited the proliferation of T cells under different concentrations of R16 (1, 10, 30 μg/ml), and the difference was statistically significant (F=11.630, 4.188, 6.011; P＜0.05). The results of flow cytometry showed that the number of Th1, Th17 and Treg cell subsets in the experimental group was decreased compared with the control group, and the difference was statistically significant (t=7.374, 4.525, 6.910; P＜0.01). There was no difference in the proportion of cells in the T cells and lymph nodes (t=1.126, 0.493, 0.178; P=0.286, 0.632, 0.862). The results of ERG showed that, compared with the control group, the amplitudes of 0.01, 3.0 cd/m2 a wave and b wave of the experiment group were all increased on the 15th day after modeling, and the differences were statistically significant (t=3.604, 4.178, 4.551, 2.566, P＜0.05).ConclusionsMSC-exosomes can reduce the clinical and pathological manifestations of EAU, protect retinal function, reduce ocular macrophage infiltration, down-regulate the proportion of inflammatory cells in the eye, and inhibit T cell proliferation.