The purpose of this study was to determine whether long-wavelength light (760 nm) promotes myopic shift in newborn guinea pigs during eye development. Newborn guinea pigs were raised in different types of illumination: long-wavelength light, mixed-wavelength light, and normal light. The guinea pigs that received long-wavelength light were raised in the illumination of long-wavelength light for 4 weeks and in the illumination of mixed light for another 2 weeks. The other animals were raised in the illumination of mixed light or normal light for 6 weeks. All the animals had measurements of refractive status and biometric parameters before and 2, 4, and 6 weeks after being raised in the illumination. Guinea pigs raised in long-wavelength light illumination developed a significant myopia, compared with those raised in mixed-light illumination after 4 weeks. Two weeks of recovery eliminated the refractive differences between the long-wavelength group and the mixed-light group. Compared with the guinea pigs raised in normal conditions, the guinea pigs raised in long-wavelength and mixed lights were more myopic and also showed longer vitreous chamber depth at 2, 4, and 6 weeks. These data suggest that illumination with monochromatic long-wavelength light may lead to myopia and to an abnormal visual experience in newborn pigmented guinea pigs.

Purpose. To evaluate the corneal biomechanical parameters in myopic and emmetropic eyes using Corneal Visualization Scheimpflug Technology (CorVis ST).Methods.103 myopic and emmetropic eyes of 103 patients were examined. Corneal biomechanical parameters, axial length, and mean keratometry were measured using CorVis ST, IOL Master, and topography, respectively. Corneal biomechanical properties were compared within four groups. Bivariate correlation analysis was used to assess the relationship between corneal biomechanical parameters and ocular characteristics.Results.Four of ten corneal biomechanical parameters, namely, deformation amplitude (DA), first- and second-applanation time (A1-time, A2-time), and radius at highest concavity (HC radius), were significantly different within the four groups (P<0.05). In correlation analysis, DA was positively correlated with axial length (r=0.20,P=0.04); A2-time was positively correlated with spherical equivalent (SE) (r=0.24,P=0.02); HC radius was positively correlated with SE (r=0.24,P=0.02) and was negatively correlated with mean keratometry (r=-0.20,P=0.046) and axial length (r=-0.21,P=0.03).Conclusions.The corneal refraction-related biomechanical alterations were associated with ocular characteristics. Highly myopic eyes exhibited longer DA and smaller HC radius than do moderately myopic eyes; the eyes with longer axial length tend to have less corneal stiffness and are easier to deform under stress.

Purpose: To analyze the conjunctival sac microbial communities in patients with Sjögren's syndrome-associated dry eyes (SSDE) and non-Sjögren's syndrome-associated dry eyes (NSSDE), compared with normal controls (NC).Methods: Conjunctival sac swab samples from 23 eyes of SSDE, 36 eyes of NSSDE, and 39 eyes of NC were collected. The V3–V4 region of the 16S ribosomal RNA (rRNA) gene high-throughput sequencing was performed on an Illumina MiSeq platform and analyzed using Quantitative Insights Into Microbial Ecology (QIIME). Alpha diversity was employed to analyze microbiome diversity through Chao1 and Shannon indexes. Beta diversity was demonstrated by the principal coordinates analysis (PCoA) and Partial Least Squares Discrimination Analysis (PLS-DA). The relative abundance was bioinformatically analyzed at the phylum and genus levels.Results: The alpha diversity was lower in patients with dry eye disease (Shannon index: NC vs. SSDE: P = 0.020, NC vs. NSSDE: P = 0.029). The beta diversity showed divergent microbiome composition in different groups (NC vs. SSDE: P = 0.001, NC vs. NSSDE: P = 0.001, NSSDE vs. SSDE: P = 0.005). The top 5 abundant phyla were Firmicutes, Proteobacteria, Actinobacteriota, Bacteroidota, and Cyanobacteria in all three groups. The top five abundant genera included Acinetobacter, Staphylococcus, Bacillus, Corynebacterium, and Clostridium_sensu_stricto_1. The relative microbiome abundance was different between groups. The Firmicutes/Bacteroidetes (F/B) ratio was 6.42, 7.31, and 9.71 in the NC, NSSDE, and SSDE groups, respectively (NC vs. SSDE: P = 0.038, NC vs. NSSDE: P = 0.991, SSDE vs. NSSDE: P = 0.048).Conclusion: The diversity of conjunctival sac microbiome in patients with NSSDE and SSDE was diminished compared with NC. The main microbiome at the phylum and genus level were similar between groups, but the relative abundance had variations. The Firmicutes/Bacteroidetes ratio was higher in the SSDE group.

To investigate the expression of complement factors in the posterior scleral fibroblasts of guinea pigs with negative lens-defocused myopia. Eighteen guinea pigs were assigned randomly to two groups: the negative lens-defocused group (NLD group, n=9) and the normal control without treatment group (NC group, n=9). The effect of myopic induction was compared in three subgroups: eyes treated with a -10.00 D negative lens in the NLD group (NL group), eyes treated with a plano (0 D) lens in the NLD group (PL group), and untreated right eyes in the NC group (NC group). The following analyses were conducted at four weeks: examination of the refractive error via retinoscopy, assessment of complement C5b-9 expression in the posterior scleral fibroblasts using immunohistochemistry, and measurements of complement C1q and C3 protein levels in the posterior sclera by Western blot. After an induction period of four weeks, a significant myopic shift was detected in the eyes of the NL group, relative to that of the PL and NC groups (P<0.05). Data analysis showed a significant increase in the percentage of C5b-9 immunopositive fibroblasts in the posterior sclera of the NL group eyes, compared to the PL group (q=11.50, P<0.001). Significantly higher levels of C1q (q=4.94, P=0.01) and C3 (q=4.07, P=0.03) protein were detected in the posterior sclera of NL group eyes, compared to the PL group. There were no significant difference between the PL and NC groups for C5b-9 (q=2.44, P=0.10), C1q (q=1.55, P=0.53) and C3 (q=0.98, P=0.77) in the posterior sclera. The data from present study provide evidence of the up-regulation of C5b-9, C1q and C3 in the posterior scleral fibroblasts in a NLD myopic animal model. The results suggest that the complement system may be involved in the development of myopia.