Glaucoma is the leading cause of irreversible blindness worldwide, with its primary risk factor arising from elevated intraocular pressure (IOP) due to an imbalance between aqueous humor production and outflow. This study aims to establish quantitative correlations among IOP, iris mechanical properties, channel microstructures, and aqueous humor dynamics through three-dimensional modeling and finite element analysis, overcoming the limitations of conventional experimental techniques in studying aqueous flow within the trabecular meshwork (TM) outflow pathway. A three-dimensional fluid-structure interaction (FSI) model incorporating the layered TM structure, Schlemm’s canal (SC), iris, and other anterior segment tissues was developed based on human ocular anatomy. FSI simulations were performed to quantify the effects of IOP variations and iris Young’s modulus on tissue morphology and aqueous humor dynamics parameters. The computational results demonstrated that axial iris deformation showed significant correlations with IOP and iris Young’s modulus. Although elevated IOP exhibited minimal effects on hydrodynamic parameters in the anterior and posterior chambers, it markedly suppressed aqueous flow velocity in the TM region. Additionally, wall shear stress in SC and collector channels displayed high sensitivity to IOP variations. These findings reveal that the tissue mechanics-FSI mechanism modulates outflow resistance by regulating aqueous humor dynamics, offering valuable references for developing clinical therapies targeting IOP reduction in glaucoma management.
Objective To investigate the risk factors of the intraocular pressure (IOP) elevation after pars plana vitrectomy (PPV). Methods Eighty-eight patients (88 eyes) of postoperative ocular hypertension in a series of 339 patients who had undergone PPV with normal ocular pressure before operation were retrospectively studied. The ocular pressures in both preoperative and postoperative periods were detected by NCT examination, and the ocular hypertension was decided on the level of ≥25 mm Hg. The relationships of occurence of the time of onset and duration of persistence of postoperative ocular hypertension with the different kinds of primary diseases, the techniques of operation, and the condition whether or not the affected eyes had formerly accepted surgical intervention, were analyzed. Results The IOP elevation occures mostly within 1 to 2 weeks postoperatively (77 eyes, 87.5%). In 65 cases (65 eyes) IOP returned to normal in 1 week, and in another 14 cases (14 eyes) in 1 month after treatments. Six patients’ (6 eyes ) IOP was under 25 to 30 mm Hg with the medicine. With sustained elevation of IOP over 4 to 6 months, 3 cases (3 eyes ) lost or almost lost their vision finally. The probability of postoperative IOP elevation in the patients suffered from the retinal detachment with proliferative vitreoretinopathy (PVR) ≥grade C-2 was the highest in all the patients in our study (38.2%, P＜0.05). The patients who had intraocular surgery before were more likely to have IOP elevation than the ones without intraocular surgery (P＜0.05). Placement of a scleral buckle, use of expansile gases or silicone oil injection and scatter endophotocoagulation intraoperatively were related to the postvitrectomy IOP elevation (γ=0.829, P＜0.001). Conclusions The previous intraocular surgeries, certain primary eye diseases and combined ocular procedures are the risk factors of IOP elevation after PPV. (Chin J Ocul Fundus Dis, 2002, 18: 106-108)
Objective To observe the effect of lowering intraocular pressure(IOP) treatment on ocular hemodynamics in patients with nonarteritic anterior ischemic optic neuropathy (NAION). Methods A total of 68 patients with NAION (68 eyes) were enrolled in this study. The patients were randomly divided into treatment group (38 eyes of 38 patients) and control group (30 eyes of 30 patients). All the patients were received methylprednisolone pulse therapy (200 mg, three days), vasodilator therapy with intravenous infusion of Xueshuantong solution (300 mg), optic nerve nutritional therapy with mouse nerve growth factor (30 mu;g) and acupoint injection in temporal with compound anisodine (2 ml). The total course was 10 days. The patients of treatment group received IOP lowering treatment to reduce the IOP to ge;8 mm Hg (1 mm Hg=0.133 kPa) or in a 30% reduction. The patients of control group received no IOP lowering treatment. The peak systolic velocity (PSV), pulsatility index (PI) and resistance index (RI) of ophthalmic artery (OA), central retinal artery (CRA) and short posterior ciliary arteries (PCA) before and after treatment were comparatively analyzed by color doppler flow imaging. Results The differences of PSV (t=1.023, 1.145, 0.569), PI (t=0.679, 0.956, 1.634) and RI (t=0.816, 1.657, 0.998) of OA, CRA and PCA before treatment in treatment group and control group were not statistically significant (P＞0.05). Compared with before treatment, PSV (t=3.150, 7.650, 3.520) and PI (t=2.420, 5.430, 7.650) of OA, CRA and PCA increased obviously (P＜0.05), RI of OA, CRA and PCA decreased obviously (t=5.320, 9.640, 18.360;P＜0.05) after treatment in treatment group. In control group, the differences of PSV (t=2.090, -2.550, -2.100) and PI (t=-2.310, -2.230, -4.490) of OA, CRA and PCA between before and after treatment were not statistically significant (P＞0.05); but the differences of RI of OA, CRA and PCA between before and after treatment was statistically significant (t=2.970, 2.160, 2.690;P＜0.05). Compared with control group, PSV (t=2.632, 2.135, 5.364) and PI (t=3.251, 2.432, 4.243) of OA, CRA and PCA increased obviously (P＜0.05), RI of OA, CRA and PCA decreased obviously (t=3.664, 2.938, 4.324;P＜0.05) after treatment in treatment group. Conclusion Lowering intraocular pressure treatment can improve the ocular hemodynamics in NAION patients.
Objective To evaluate the efficacy and safety of latanoprost versus travoprost for primary open-angle glaucoma (OAG) and ocular hypertension (OH). Methods All the randomized controlled trials (RCTs) about treating primary open-angle glaucoma and ocular hypertension with latanoprost and travoprost were collected by searching MEDLINE, EMbase, OVID and CNKI. The assessment of methodological quality and data extraction of the included studies were performed independently by two reviewers, and the meta-analysis was conducted with RevMan 5.0 software. Results A total of 13 RCTs involving 1 433 patients were included. The results of meta-analyses showed that, a) At the second week, travoprost showed greater intraocular pressure (IOP) lowering efficacy compared with latanoprost (WMD= –1.47, 95%CI –2.62 to –0.33). At the first month (WMD= –0.50, 95%CI –1.52 to 0.52) and the sixth month (WMD= –0.12, 95%CI –0.85 to 0.61), the difference of IOP reduction between latanoprost and travoprost group was not significant; and b) The latanoprost-treated group showed fewer reported conjunctival congestion than the travoprost-treated group (OR=0.47, 95%CI 0.35 to 0.63). The difference in adverse events of eye pain (OR=0.55, 95%CI 0.27 to 1.12) and iris or skin depigmentation (OR=1.25, 95%CI 0.53 to 2.92) between latanoprost and travoprost group was not significant. Conclusion Latanoprost and travoprost are comparable in lowering IOP for OAG and OH patients. Latanoprost shows greater ocular tolerability with lower incidence of side effects as conjunctival congestion. This conclusion is not powerful enough in proof due to the medium methodology quality of the included studies, so a large number of high-quality RCTs with large sample are needed for objectively, entirely and precisely evaluating the efficacy.
Objective To observe the clinical characteristics of steroid-induced ocular hypertension (SIOH) in patients with uveitis, and explore the relationship between its clinical phenotype and gene polymorphism. Methods A retrospective case-control study. From July 2019 to December 2020, 576 patients with uveitis who were treated with glucocorticoid eye drops in Tianjin Medical University Eye Hospital were included in the study. Among them, there were 175 confirmed glucocorticoid responders (SRs) and 401 glucocorticoid non-responders (NRs). Seventy cases of SRs (age ≥18 years) using 1% prednisone acetate eye drops were selected as the experiment group and 64 cases of NRs were selected as the control group. The polymorphism of rs2523864 and rs3873352 of human leukocyte antigen complex group (HCG) 22 gene were detected by Sanger sequencing. To observe the clinical characteristics of SIOH after the use of glucocorticoid eye drops, and the correlation between rs2523864 and rs3873352 and the occurrence of SIOH. Differences among groups were compared with the Chi-square test or Fisher's exact test. The correlation between the occurrence of SIOH and the range of intraocular pressure increases after glucocorticoid use and the rs2523864 and rs3873352 loci were compared using the odds ratio (OR) and its 95% confidence interval (CI). Results SIOH occurred in 175 (30.4%, 175/576) of 576 patients. Among them, there were 96 males (54.9%, 96/175) and 79 females (45.1%, 79/175); the average age was 33.64±17.40 years. Steroid high responders (HRs) and steroid moderate responders (MRs) were 58 (33.1%, 58/175) and 117 (66.9%, 117/175) cases. The medication time for the increase in intraocular pressure in MRs that was 33 (19, 56) days, and in HRs that was 28 (14, 36) days, the difference of which was significant (Z=－1.999, P=0.046). No differences were found in daily doses of ocular hypertension induced by 1% prednisone acetate eye drops between MRs which was 4.24 (3.46, 4.66) drops/day and HRs that was 4.32 (3.84, 5.36) drops/day (Z=－1.676, P=0.094). The genotype and allele frequency distribution of the rs3873352 locus in the case group and HRs group were significantly different from those in the control group (P＜0.05). The intraocular pressure with rs3873352 GG genotype after the medication was higher than that with GC and CC genotype (Z=2.855, 2.628; P=0.013, 0.026), whereas there was no significant difference between different genotypes of rs2523864 (Z=3.580, P＞0.05). Genetic model analysis revealed the risk of SIOH in rs3873352 G allele carriers (GG+GC) was 2.048 times that of non-G allele carriers (OR=2.048, 95%CI: 1.027-4.081, P=0.041). The genotype and allele frequency of rs2523864 locus showed no significant difference between different group (P＞0.05). Conclusions After the use of glucocorticoid eye drops, HRs have an earlier increase in intraocular pressure than MRs. HCG22-rs3873352 gene polymorphism is related to the occurrence of SIOH, GG genotype increases the risk of SIOH, and G allele is a risk gene for SIOH.
The occurrence of high intraocular pressure (IOP) after vitrectomy for diabetic retinopathy (DR) is related to many factors, including the type and stage of DR, macular detachment, surgical methods, and the type of ocular tamponade. Early high IOP occurred mainly due to laser photocoagulation, inflammatory response, improper ocular tamponade, residual viscoelastic agents and ciliary body dysfunction. In addition to the above reasons, early-middle stage high IOP is also related to tamponade gas expansion peak, encircling scleral buckle and hyphema. The major reason for middle-stage high IOP is hyphema and silicon oil in anterior chamber. The reasons for late-stage high IOP are glaucoma, silicone oil emulsification, long-term use of glucocorticoid, and iris incision closure. Most high IOP can be controlled by proper treatment such as stopping use of glucocorticoid, anti-glaucoma eye drops and surgeries. But there are still a small number of patients with unexplained refractory high IOP, the mechanism need to be further explored.