Scleral structure and biomechanics

Suprachoroidal space-inducing hydrogel-forming microneedles (SI-HFMN): An innovative platform for drug delivery to the posterior segment of the eye

The suprachoroidal space (SCS), which exists between the sclera and choroid, offers a promising delivery route to the posterior segment of the eye (PSE) and is integrated with hollow microneedles (HMNs) for minimally invasive delivery. However, HMNs are limited by backflow owing to their narrow channel. Therefore, this study proposes a biocompatible SCS-inducing hydrogel-forming microneedle (SI-HFMN) with a specially designed candlelit shape that swells to separate the sclera from the choroid. The induced SCS provides a route for delivering loaded drugs to the PSE upon application. The optimized formulation of 20 % (w/w) poly(methyl vinyl ether-alt-maleic acid) (PMVE/MA) crosslinked with 7.5 % (w/w) polyethylene glycol (PEG) possesses sufficient mechanical strength (5.1 ± 0.7 N) to penetrate both the sclera and swell by 356 ± 28 %, to mechanically stimulate SCS formation. The formulation also recorded a drug absorption amount of 101 ± 9 μg/mg of hydrogel. Furthermore, in vitro and ex vivo experiments demonstrated the ability of the SI-HFMN to deliver drugs to the PSE via the formed SCS. Thus, this system offers an innovative method for drug delivery to PSE by inducing SCS formation.

Bio-interventional Uveoscleral Outflow Enhancement Surgery for Primary Open-Angle Glaucoma: 2-Year Results of Cyclodialysis with Scleral Allograft Reinforcement

Objective

To evaluate safety and efficacy of the scleral allograft-reinforced cyclodialysis through 24 months of follow-up.

Design

Interventional single-center case series.

Participants

Thirty-one eyes with primary open-angle glaucoma and visually significant cataracts underwent bio-interventional cyclodialysis surgery with scleral allograft reinforcement combined with phacoemulsification.

Intervention

Uveoscleral outflow enhancement surgery comprised of cyclodialysis with sequential bio-reinforcement with a scleral allograft combined with phacoemulsification.

Main Outcome Measures

The primary outcome was the proportion of eyes achieving ≥20% intraocular pressure (IOP) reduction with same or fewer medications compared with baseline. Secondary outcomes included the mean change in medicated IOP and mean number of IOP-lowering medications compared with baseline. Adverse events were also recorded and evaluated throughout the study.

Results

The primary outcome was achieved in 74% of the eyes, and there was a mean IOP reduction of 34% compared with baseline. Baseline mean medicated IOP was 21.9 ± 4.92 mmHg on 1.22 ± 1.29 IOP-lowering medications. At 12 months postoperation, mean IOP was 12.62 ± 2.63 on 0.55 ± 0.52 glaucoma medications. The procedure was well tolerated, and there were no serious ocular adverse events.

Conclusions

Uveoscleral outflow enhancement can be successfully achieved at the time of cataract surgery through bio-interventional cyclodialysis and scleral allograft reinforcement to lower IOP in patients with primary open-angle glaucoma.

Financial Disclosures

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Scleral ultrastructure in young rhesus monkeys: A stereological approach

The sclera provides mechanical support to the globe and plays a key role in maintenance of ocular structural integrity. Evidence shows that scleral remodeling contributes to biomechanical weakening, increasing the risk of pathologies, such as glaucoma and posterior staphyloma in high myopia. A precise characterization of normal regional ultrastructure is needed for a better understanding of scleral remodeling. The purpose of this study was to develop and implement a stereological analysis method to characterize scleral ultrastructure in healthy young rhesus monkey eyes. Monkeys (N = 4 eyes) first underwent normal emmetropization in a primate nursery. At 150 days of age, scleral tissue was collected in 1 mm2 sections from three regions, equatorial nasal, posterior, and equatorial temporal, and processed for transmission electron microscopy (TEM). Images were captured at three depths: outer, middle, and inner, for all regions. Scleral thickness, fibroblast volume fraction, volume fraction of fibrillin microfibrils, and collagen fibril diameters were quantified using stereology and manual segmentation. The sclera was thickest in the posterior region with a mean thickness of 217.1 ± 10.1 μm. A total of 103 micrographs were analyzed to compute the volume fraction of fibroblasts and fibrillin microfibrils. Median fibroblast volume fraction was 7.4 %, and fibrillin microfibril volume fraction was 1.8 %. A total of 3564 collagen fibrils, encompassing 99 fibrils per region and depth per eye, were analyzed. Median collagen fibril diameter was 79.8 nm and ranged from 23 nm to 205 nm. This stereological approach provides a foundation for future studies investigating myopic scleral remodeling, where axial elongation and scleral thinning are known to show regional differences.

Influence of scleral thickness on photodynamic therapy outcomes in central serous chorioretinopathy

PURPOSE

To test the prognostic role of anterior scleral substantia propria (ASSP) thickness in predicting the 3-month response after half-dose photodynamic therapy (PDT) in central serous chorioretinopathy (CSCR) and to assess its clinical relevance of ASSP in different CSCR phenotypes.

METHODS

A prospective, exploratory, multi-centre cohort study conducted at IRCCS San Martino Hospital (Genoa, Italy) and Jules-Gonin Eye Hospital (Lausanne, Switzerland). Demographic and clinical data, and optical coherence tomography (OCT) were collected at baseline and 3 months after PDT. Based on OCT images, we categorized CSCR phenotypes and collected clinically relevant imaging metrics. ASSP thickness was obtained from four different measurements using anterior segment (AS) OCT. Multivariable regression models were performed to evaluate the distribution of ASSP thicknesses among different CSCR phenotypes and to test the prognostic role of ASSP thickness in discriminating between PDT responders (complete subretinal fluid reabsorption) and partial responders.

RESULTS

The study cohort comprised 109 Caucasian patients (82 males, 75.2%) with a total of 142 eyes: 84 eyes simple (59.1%) versus 58 eyes complex (40.9%) CSCR. A linear normal model confirmed a positive association between complex CSCR and higher ASSP thickness (β = 26.1, 95% CL = 12.1/40.1, p < 0.001), with a low prevalence of ciliochoroidal effusion loculations in AS-OCT (1/142 eyes, 0.7%). ASSP thickening was positively linked to the presence of posterior cystoid retinal degeneration (PCRD; p = 0.002), indicating a potential role in the pathogenesis of severe CSCR phenotypes. In the subgroup of treated patients (61 eyes), 63.9% had a complete response after PDT. In these patients a logistic binary model highlighted a significantly higher risk of PDT non-responsiveness (OR = 9.62, 95% CL = 2.44/37.9, p = 0.001) associated with a 60-unit increase in ASSP thickness levels. By contrast, other anatomical parameters (i.e., body surface area, age, gender, axial length) showed no remarkable prognostic roles.

CONCLUSION

This research highlighted the association of ASSP thickening with complex CSCR phenotype in Caucasian patients and its role in predicting PDT efficacy. These findings enhance our comprehension of the anatomical risk factors in patients affected with CSCR and potentially guide a better understanding of non-responsive cases to PDT treatment.

Strain heterogeneity measurement of mouse sclera by stereo digital image correlation under inflation testing

Scleral biomechanics has emerged as an important topic in eye research, particularly for understanding the pathophysiology of diseases such as myopia and glaucoma. For the biomechanical characterization of scleral tissue, the three-dimensional digital image correlation (3D-DIC) method has been widely used as an accurate optical tool for full-field deformation measurements during ex vivo inflation testing in different species like cow, pig, human, rat, and tree shrew, with a large range of eye size roughly between 38 mm and 7 mm. Mouse has been used as the common model in glaucoma and more recently in myopia research, but until now, due to the small eye size (~ 4 mm in diameter), no stereo-DIC has been proposed for whole-eye inflation testing. We present the first setup of inflation testing of intact mouse eyes for measuring the strain field of the sclera by the 3D-DIC method during quasi-static pressure loading, along with an analysis of the variables required to design a stereo-DIC system. In addition, we investigated the biomechanical characterization of mouse sclera, and the evolution of the sclera strain distribution during a loading-unloading cycle. We discovered that the scleral strain distribution during quasi-static linear changes of intraocular pressure (IOP) follows a Lognormal distribution whose standard deviation represents a metric of the biomechanical heterogeneity of the strain response.

Distinct metabolome and flux responses in the retinal pigment epithelium to cytokines associated with age-related macular degeneration: comparison of ARPE-19 cells and eyecups

Age-related macular degeneration (AMD) is associated with chronic inflammation of the retinal pigment epithelium (RPE) and elevated cytokines including TNFα, TGF-β, IL-6, and IL-1β. As a metabolic intermediary supporting aerobic glycolysis in the adjacent photoreceptors, the RPE's metabolic responses to inflammation and the optimal methods to study cytokine-driven metabolic programming remain unclear. We performed a rigorous comparison of ARPE-19 cells and rat eyecup metabolomes, revealing key distinctions. Rat eyecups exhibit higher levels of lactate and palmitate but depleted glutathione and high-energy nucleotides. Conversely, ARPE-19 cells are enriched with high-energy currency metabolites and the membrane phospholipid precursors phosphocholine and inositol. Both models showed contrasting responses to individual cytokines: ARPE-19 cells were more sensitive to TNFα, while eyecups responded more strongly to TGF-β2. Notably, a combined cytokine cocktail elicited stronger metabolic effects on ARPE-19 cells, more potently impacting both metabolite abundance (41 vs. 29) and glucose carbon flux (29 vs. 5), and influencing key RPE metabolites such as alanine, glycine, aspartate, proline, citrate, α-ketoglutarate, and palmitate. Overall, these findings position ARPE-19 cells as a more responsive platform for studying inflammatory cytokine effects on RPE metabolism and reveal critical RPE metabolites which may be linked with AMD pathogenesis.

Covariation of scleral remodeling and PI3K/Akt signaling pathway in experimental myopia

The present study aimed to investigate the role of the PI3K/Akt signaling pathway in scleral remodeling in the development of negative lens-induced myopia (LIM). The change of scleral morphology in experimental myopic guinea pigs was observed by transmission electron microscopy, Masson staining, and TUNEL assay, respectively. Meanwhile, the levels of the PI3K/AKT signaling pathway- and scleral remodeling-related molecules in scleral tissues were determined by real-time quantitative PCR (qPCR), enzyme-linked immunosorbent assay (ELISA), immunofluorescence, immunohistochemical staining, and western blot, respectively. We found that 2-week myopic induction can elevate PIK3R3 and AKT2 levels and activate the PI3K/Akt signaling pathway, enhance the expression of E-cadherin and matrix metallopeptidase 2 (MMP2), and decrease the level of transforming growth factor-beta 1 (TGF-β1), tissue inhibitor of matrix metalloproteinase-2 (TIMP2), and collagen (COLI) in the scleral tissue of myopic guinea pigs, thereby leading to scleral remolding. However, 4-week myopic induction could inhibit the PI3K/AKT signaling pathway and induce apoptosis, accompanied by increased MMP2, E-cadherin, and decreased TGF-β1, TIMP2, and COLI. Results reveal that the disturbed PI3K/AKT signaling plays a role in scleral remodeling in the experimental myopia through orchestrating apoptosis.

Analysis of the sclera elasticity properties and comparison with corneal biomechanics properties in vivo and in vitro

PURPOSE

To explore scleral elastic modulus and its correlation with corneal biomechanics in vivo and in vitro, and to introduce a predictive model for non-destructive characterization of scleral and corneal elastic modulus.

METHODS

In vivo biomechanical parameters of 21 rabbit eyes were measured using the Corvis ST. Uniaxial tensile tests on corneal and scleral (anterior, equatorial, and posterior sections) strips provided low-strain and high-strain tangent elastic modulus (LSTM and HSTM). Pearson's and Spearman's correlation analyses were used to examine the relationship. A multivariate linear regression model was used to characterize the elastic modulus in vivo. Transmission electron microscopy was used to elucidate the arrangement of collagen fibers in the anterior, equatorial, and posterior sclera.

RESULTS

Twelve in vivo parameters significantly correlate with the corneal LSTM (P < 0.05), whereas no parameters are correlated with the corneal HSTM. SP-HC (Rho = 0.442) and HC Deflection Amp (HC DA, r = -0.605) correlated with anterior sclera LSTM. DA ratio 1 mm (r = 0.446) was correlated with the equatorial sclera LSTM. Integrated Radius (Rho = 0.483) and Radius (r = -0.473) were correlated with the equatorial sclera HSTM. The representative multivariate linear regression model indicated the follows: Corneal LSTM = 0.046 + 0.01 ∗ SP-A1 + 0.066 ∗ SSI. Anterior sclera LSTM = 0.294-0.120 ∗ HC DA. Equatorial sclera LSTM = 0.22 + 0.114 ∗ DA Ratio 1 mm - 0.049 ∗ HC DA.

CONCLUSIONS

Biomechanical parameters, such as SP-A1 and SSI, correlate with the low-strain elasticity of the cornea, which primarily reflects the properties of the corneal ground matrix. Corvis ST may not be able to detect biomechanics changes in the cornea collagen structure. The scleral elastic modulus prediction model offers new insights into the non-destructive characterization of scleral biomechanics.

Ciliary muscle traction during accommodation is able to induce optic nerve head deformation

OBJECTIVES

To use finite element (FE) modeling and in vivo optical coherence tomography (OCT) imaging to explore the effect of ciliary muscle traction on optic nerve head (ONH) deformation during accommodation.

METHODS

We developed a FE model to mimic the ciliary muscle traction during accommodation, and varied the stiffness of the sclera, choroid, Bruch's membrane (BM), prelaminar neural tissue and lamina cribrosa (LC) to assess their effects on accommodation-induced ONH strains. To validate the FE model, OCT images of the right eyes' ONHs from 20 subjects (25 ± 1.5 years, range: 24-28 years) were taken for an accommodative stimulus of 6-diopters (6D) and a relaxed state of 0D. Based on OCT images, the accommodation-induced ONH effective strains, choroidal thickness and BM opening (BMO) changes were measured.

RESULTS

Our FE model predicted that the ciliary muscle pulling force could be transmitted to the ONH through the choroid and BM. The LC strain caused by the ciliary muscle pulling (0.0177) is comparable to that induced by an IOP elevation of 45 mmHg (0.0173). The accommodation-induced LC strain increased with stiffer choroid and BM. Three-dimensional strain tracking showed that the LC strains under 6D and 0D accommodation were 0.057 ± 0.033 and 0.023 ± 0.014 (p < 0.05). The reduction in choroidal thickness and the enlargement in BMO were observed during accommodation.

CONCLUSIONS

Our study showed that during accommodation, ciliary muscle traction could induce large ONH deformations and that stiffer choroid and BM increased the pulling force transmitted to the ONH, thereby leading to higher LC strains.

Spatial heterogeneity of corneal biomechanical properties in myopia at nanoscale: A preliminary study

PURPOSE

To investigate the spatial heterogeneity of the corneal biomechanical properties in individuals with non-high and high myopia.

METHODS

Atomic force microscopy was used to quantify the region-dependent elastic modulus (E) of 34 corneal lenticules from keratorefractive lenticule extraction surgery. The local E values of the central region, as well as the superior, inferior, nasal, and temporal points at the pericentral region, were measured. Differences between non-high myopia (-6.0 D < spherical equivalent [SE] ≤ -0.5 D) and high myopia (SE ≤ -6.0 D) were compared.

RESULTS

E was significantly higher in the non-high myopia group than in the high myopia group (P < 0.0001). In non-high myopia, the central cornea exhibited a higher E than its pericentral counterpart (P < 0.0001), and the pericentral region E was higher in the horizontal direction than in the vertical direction (P = 0.0393). However, these values converged to be similar in high myopia (P = 0.5973, P = 0.7799). No significant differences in E were found between the superior and inferior pericentral corneas, nor between the nasal and temporal in both non-high (P = 0.0931, P = 0.1800) and high myopia (P = 0.5154, P = 0.1007). The E values of central and pericentral cornea were positively correlated with the mean radius of the posterior corneal surface (r = 0.3747, P = 0.0290; r = 0.3961, P = 0.0204).

CONCLUSION

In non-high myopia, region-dependent corneal biomechanics revealed higher stiffness centrally than pericentrally, with pericentral cornea stiffer horizontally than vertically. High myopia exhibited a reduced E and a gradual loss of spatial heterogeneity. Emphasizing spatial heterogeneity is crucial for a comprehensive understanding of the biomechanical behavior in myopia.

Whorl-Like Collagen Fiber Arrangement Around Emissary Canals in the Posterior Sclera

Purpose

To investigate the collagen fiber arrangement around emissary canals in the posterior sclera.

Methods

One hundred sixty-five eyes of 93 patients who underwent polarization-sensitive optical coherence tomography (PS-OCT) examinations in 2019 in the Institute of Science Tokyo were studied. Multimodal imaging, including streamline images derived from PS-OCT data, B-scan images, and indocyanine green angiography (ICGA) images, was used to investigate the collagen fiber arrangement around emissary canals and scleral pits in vivo. Additionally, the collagen fiber arrangement around the emissary canals in porcine sclera was examined using scanning electron microscopy and light microscopy.

Results

Streamline images showed whorl-like collagen fiber arrangements on all eyes, and 25 eyes were selected for the analysis. All whorls corresponded to emissary canals on B-scan images. The whorls were confirmed to correspond to the posterior ciliary artery entries in three eyes and posterior vortex vein exits in three eyes with available ICGA images. Streamline cutaway images showed that the whorls surrounded the emissary canals throughout the entire course. In 16 eyes with 20 scleral pits, whorls were seen surrounding all the pits. Microscopic study using porcine sclera confirmed the whorl-like structures around the emissary canals ex vivo and demonstrated tangentially arranged collagen fiber bundles forming the circle.

Conclusions

The collagen fibers are arranged as whorl-like structures around the vessel emissary canals in the posterior sclera, which is a knowledge gap for basic scleral histology. Additionally, this study demonstrated a strong correlation between PS-OCT findings and microscopic histology, underscoring PS-OCT's utility in detecting scleral collagen fiber arrangements.

EFEMP1-Mediated Regulation of Choroidal Vascular Dysfunction in Myopia: Insights Into the FOXO3/VEGFA Pathway as a Therapeutic Target

Purpose

This study investigates the role of EFEMP1 in choroidal vascular dysfunction and its implications for myopia progression, specifically focusing on the FOXO3/VEGFA signaling pathway as a potential therapeutic target.

Methods

We utilized adeno-associated virus (AAV) to overexpress and knock down EFEMP1 in the choroid of guinea pigs. Subsequent proteomic analyses were conducted on the choroidal tissue. We used Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) to identify relevant pathways and genes. In vitro experiments were performed on RF/6A cells, where both EFEMP1 and FOXO3 underwent overexpression and knockdown. We conducted a series of cell culture experiments, including assessments of cell proliferation, migration, tube formation, and choroidal sprouting assays, to evaluate the functional effects of EFEMP1. Quantitative reverse transcription PCR and Western blot analyses were utilized to measure gene and protein expression levels.

Results

Silencing EFEMP1 significantly reduced choroidal vascular dysfunction and slowed the progression of myopia. Proteomic analysis demonstrated that EFEMP1 regulates FOXO3 activity, resulting in increased VEGFA expression in RF/6A cells and promoting angiogenesis. Conversely, knockdown of FOXO3 led to decreased VEGFA levels, confirming that EFEMP1 modulates VEGFA expression through FOXO3.

Conclusions

Targeting EFEMP1 may offer a novel therapeutic strategy for the prevention and treatment of myopia by alleviating associated vascular dysregulation. Further exploration of the FOXO3/VEGFA pathway could provide additional insights into therapeutic interventions for myopia.

Anterior Segment Anatomic Parameters Based on the Scleral Spur and Cornea for Risk Profiling of Primary Angle Closure Glaucoma

INTRODUCTION

The aim of the study was to investigate the anterior segment anatomical parameters associated with the scleral spur and cornea for risk profiling of primary angle closure glaucoma (PACG).

METHODS

A retrospective study was conducted, collecting parametric measurements obtained using CASIA 2 and IOLMaster 700. Univariate and multivariate logistic regression models were utilized to compare ocular parameters between the narrow angle (NA) group and PACG group, as well as identify risk factors for PACG. The predictive performance of each parameter was evaluated using the area under the receiver operating characteristic (AUROC) curve.

RESULTS

A total of 84 patients with PACG (48 with PACG and 36 with chronic PACG) and 84 patients with NA were included in this study. In the multivariable model, it was demonstrated that individuals with a smaller trabecular scleral-spur angle (TSA: OR = 0.810, per 1° increase, p < 0.001, AUROC = 0.738) and larger relative lens vault (rLV: OR = 1.112, per 1 percent increase, p < 0.001, AUROC = 0.720) had an increased risk of developing PACG. Furthermore, combining TSA with rLV yielded an improved AUROC value of 0.807 (p < 0.001).

CONCLUSION

AS-OCT is a valuable tool for early assessment of progression risk in NA patients at risk for developing PACG. Our findings suggest that both TSA and rLV are significant risk factors for PACG. Moreover, the novel parameter TSA demonstrates promising potential as a predictive tool for early PACG screening.

Assessment of anterior scleral thickness in Turkish open angle glaucoma patients: an anterior segment optical coherence tomography study

BACKGROUND

To compare anterior scleral thickness (AST) in Turkish patients with open-angle glaucoma (primary open-angle glaucoma (POAG) and pseudoexfoliation glaucoma (PEG)) with healthy controls.

METHODS

This prospective study involved 41 patients with PEG, 69 patients with POAG, and 46 healthy controls. We obtained spectral domain anterior segment optical coherence tomography (AS-OCT) images from the nasal and temporal quadrants and made AST measurements of 1 mm (AST), 2 mm (AST2), 3 mm (AST3), and 4 mm (AST4) posterior to the scleral spur (SS). Schlemm's canal (SC) diameter and area measurements were performed using the ImageJ software. The results were compared statistically.

RESULTS

The average ASTs of the groups did not differ significantly (p > 0.05 for each). The analysis of the nasal SC diameter revealed a significant decrease in the POAG group in comparison with the PEG group, with no difference observed between the POAG and control groups (p = 0.038*). The mean nasal and temporal SC area was significantly smaller in the PEG and POAG groups compared with the control group (p < 0.001** and p < 0.001**, respectively).

CONCLUSIONS

There was no significant difference in nasal and temporal AST between groups; however, the SC area was found to be smaller in glaucoma groups compared with healthy controls. The present findings should be supported by further studies.

Optic Disc Size and Circumpapillary Retinal Nerve Fiber Layer Thinning in Glaucoma

PURPOSE

To investigate the association between optic disc size and circumpapillary retinal nerve fiber layer (cpRNFL) thinning in eyes with preperimetric glaucoma and glaucoma.

DESIGN

Observational cohort.

PARTICIPANTS

A total of 841 eyes (554 primary open angle glaucoma and 287 preperimetric glaucoma) from 553 patients who had at least 4 visits and 2 years of follow-up using OCT.

METHODS

Multivariable linear mixed-effects modeling was used to estimate the effect of optic disc size on cpRNFL thinning while controlling for covariates. To eliminate the floor effect, eyes with baseline visual field mean deviation less than -14 dB were excluded.

MAIN OUTCOME MEASURES

The effect of optic disc size on cpRNFL thinning.

RESULTS

Of the participants, 189 (34.2%) were Black, 338 (61.1%) were White, 20 (3.6%) were Asian, and 6 (1.1%) were another race or ethnicity. Mean follow-up period was 5.3 (95% confidence interval [CI], 5.2-5.5) years, and the mean rate of cpRNFL change was -0.54 (95% CI, -0.61 to 0.47) μm/year. After adjusting for covariates with the Littmann's formula correction, larger optic disc size was associated with faster cpRNFL thinning (-0.03; 95% CI, -0.05 to 0.00) μm/year faster per 0.1 mm2 larger; P = 0.034), while no significant differences were found for race and its interaction with optic disc size.

CONCLUSIONS

Larger optic disc size is associated with faster cpRNFL thinning in glaucoma, independent of race. Although previous studies have indicated that Black individuals may be at higher risk for glaucoma development, the present study suggests that race may not be a significant predictor of faster cpRNFL thinning when controlling for optic disc size and other clinical and demographic factors in glaucoma.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

The role of NF-κB pathway and its regulation of inflammatory cytokines in scleral remodeling of form-deprivation mice model

Myopia has become a worldwide public health problem. In this study, we constructed a form deprivation (FD) myopia mouse model and explored the potential role of NF-κB pathway and inflammatory cytokines in scleral remodeling during myopia development. Wild-type (WT) mice and C6-knockout (KO) mice were categorized into two groups: FD and normal control (NC). The right eye was covered using a translucent balloon for 4 weeks, and the left eye remained untreated which served as self-control. NC group received no treatment. Refractive error and axial length were measured at baseline, 2 weeks, 4 weeks later under normal visual conditions, and 4 weeks after FD. The mRNA and protein levels of scleral TNF-α, IL-6, IL-1β, MMP-2, collagen I, and p-NF-κB p65 were detected using quantitative PCR and western blot. Under normal visual conditions, no significant difference existed in refraction and axial length between WT and C6 KO mice. After 4 weeks of deprivation, the interocular differences of C6 KO mice were lower than those of WT mice (refraction - 2.41 ± 0.86D vs. - 4.33 ± 0.87D, P = 0.003; axial length 0.044 ± 0.028 mm vs. 0.082 ± 0.026 mm, P = 0.034). Moreover, TNF-α, IL-6, IL-1β, MMP-2, and p-NF-κB p65 levels increased, and collagen I levels decreased in deprived eyes of WT mice. Whereas these trends were weakened in C6 KO mice. Scleral C5b-9 could activate the NF-κB pathway, promoting the expression of inflammatory cytokines and MMP-2 levels, which ultimately affected scleral remodeling.

Knowledge, attitudes and practice toward refractive errors management among left-behind children of migrant workers

Background

This study aimed to access knowledge, attitudes and practice (KAP) regarding refractive errors (RE) management among the left-behind children of migrant workers.

Methods

This cross-sectional study was performed by the Ophthalmology Department of Beijing Jishuitan Hospital between July and August, 2023. The KAP scores were assessed using a self-designed questionnaire.

Results

Analysis of 350 questionnaires showed mean KAP scores of 9.21 ± 3.00 (possible range 0-14), 33.23 ± 3.57 (possible range 9-45), and 50.19 ± 5.31 (possible range 14-70), respectively. Pearson's correlation analysis showed positive correlation was found between knowledge and practice (r = 0.286, p < 0.001), negative correlation between knowledge and attitude (r = -0.150, p = 0.005), and positive correlation between attitude and practice (r = 0.141, p = 0.008). Multivariate logistic regression analysis showed that children's age (OR = 0.748, 95%CI: 0.632-0.885, p = 0.001), duration away from parents (OR = 0.345, 95%CI: 0.172-0.691, p = 0.003) and RE in parents (OR = 0.405, 95%CI: 0.218-0.753, p = 0.004) were independently associated with knowledge. Relationship to the child other than grandparent (OR = 0.252, 95%CI: 0.064-0.999, p = 0.050), as well as child's gender (female, OR = 1.671, 95%CI: 1.006-2.777, p = 0.047) and duration of sleep per day (OR = 8.401, 95%CI: 1.473-47.923, p = 0.017) were independently associated with practice. In addition, structural equation modeling also showed positive impact of knowledge on practice (β = 1.251, p < 0.001).

Conclusion

Left-behind children of migrant workers have mostly sufficient knowledge, positive attitude and proactive practice toward RE management, significantly influenced by child's age, relationship with the child, and duration of living without parents.

Evaluation of Scleral Thickness in Patients With Keratoconus

OBJECTIVES

To evaluate scleral thickness of patients with keratoconus by anterior segment optical coherence tomography (AS-OCT).

MATERIALS AND METHODS

Fifty-two eyes of 42 patients with keratoconus (group 1) and 42 right eyes of 42 healthy individuals (group 2) were included. Scleral thickness measurements were taken with AS-OCT 6, 4, and 2 mm behind the scleral spur in four gaze positions: superior, inferior, temporal, and nasal. The data including central corneal thickness (CCT) by Pentacam from patients with keratoconus was also analyzed and its relationship with scleral thickness was evaluated.

RESULTS

In group 1, mean scleral thickness from 6 mm posterior to scleral spur in superior, inferior, temporal, and nasal quadrants were 397±35.3 (320-482), 408±29.5 (341-467), 393±40.8 (297-469), and 403±35.8 (310-482) μm, respectively. In group 2, mean scleral thickness from 6 mm posterior to scleral spur in superior, inferior, temporal, and nasal quadrants were 440±42.2 (346-552), 461±33.9 (390-563), 451±46.6 (340-549) and 448±34.3 (350-521) μm, respectively. The mean scleral thickness in group 1 was significantly lower in all quadrants compared with group 2 ( P <0.001). The mean CCT in group 1 was 478.22±87.55 (306-632) μm. Positive correlation was found between scleral thickness measurements taken at 4 mm (ϱ=0.312, P =0.037) and 2 mm (ϱ=0.308, P =0.039) posterior from the scleral spur in the inferior quadrant and CCT.

CONCLUSION

Scleral thickness was significantly lower in patients with keratoconus. Scleral thickness and CCT were positively correlated in inferior quadrant. Even though it is not yet known whether scleral changes are progressive or not, scleral thickness measurement may also find a place in the diagnosis and follow-up of patients with keratoconus in the future.

The Ocular Surface and the Anterior Segment of the Eye in the Pseudoexfoliation Syndrome: A Comprehensive Review

Pseudoexfoliation syndrome (PXS) is an age-related fibrillopathy where fibrillar exfoliation material accumulates and deposits in ocular and extra-ocular tissue. Within the eye, this substance accumulates on the ocular surface and in the anterior segment of the eye, impacting ocular structures such as the conjunctiva, Tenon's capsule, sclera, cornea, iris, ciliary body, trabecular meshwork, and lens. This review aims to collate the current literature on how each anatomical part of the eye is affected by PXS, with a strong focus on molecular changes. We also summarise the current understanding of the key genetic factors influencing the development of PXS.

Horizontal Gaze Tolerance and Its Effects on Visual Sensitivity in Glaucoma

Purpose

This study evaluates the effect of 6° horizontal gaze tolerance on visual field mean sensitivity (MS) in patients with glaucoma using a binocular head-mounted automated perimeter, following findings of structural changes in the posterior globe from magnetic resonance imaging and optical coherence tomography.

Methods

In this cross-sectional study, a total of 161 eyes (85 primary open-angle glaucoma [POAG] and 76 healthy) from 117 participants were included. Logistic regression and 1:1 matched analysis assessed the propensity score for glaucoma and healthy eyes, considering age, sex, and axial length as confounders. Visual field tests were performed with the imo perimeter (CREWT Medical Systems, Inc., Tokyo, Japan) at central gaze, 6° abduction, and 6° adduction positions as fixation points. A mixed-effects model was used to compare MS under all conditions.

Results

The analysis included a total of 82 eyes, with 41 POAG and 41 healthy after matching. The mean (standard deviation) age was 68.0 (11.0) years, with a mean deviation of -9.9 (6.6) dB for POAG and -1.0 (1.9) dB for healthy eyes using Humphrey field analysis 24-2. MS did not significantly differ among central gaze (27.0 [1.8] dB), abduction (27.1 [1.9] dB), and adduction (26.9 [2.2] dB) in healthy eyes (P = 0.650). However, MS was significantly lower for adduction (17.2 [5.9] dB) compared to central gaze (18.1 [5.9] dB) and abduction (17.9 [5.9] dB) in glaucoma eyes (P = 0.001 and P = 0.022, respectively).

Conclusions

Horizontal gaze, especially in adduction, significantly reduces visual sensitivity in glaucoma, suggesting a specific vulnerability associated with eye movement. This finding highlights the importance of eye positioning in glaucoma, warranting further investigation of its clinical significance.

An Evidence-Based Narrative Review of Scleral Hypoxia Theory in Myopia: From Mechanisms to Treatments

Myopia is one of the dominant causes of visual impairment in the world. Pathological myopia could even lead to other serious eye diseases. Researchers have reached a consensus that myopia could be caused by both environmental and genetic risk factors. Exploring the pathological mechanism of myopia can provide a scientific basis for developing measures to delay the progression of myopia or even treat it. Recent advances highlight that scleral hypoxia could be an important factor in promoting myopia. In this review, we summarized the role of scleral hypoxia in the pathology of myopia and also provided interventions for myopia that target scleral hypoxia directly or indirectly. We hope this review will aid in the development of novel therapeutic strategies and drugs for myopia.

Effect of axial elongation on anterior scleral thickness in myopia

OBJECTIVE

This study aimed to investigate the effect of axial elongation on anterior scleral thickness (AST) in myopia.

METHODS

The convenience sampling method was used to select 122 patients without ocular or systemic diseases affecting ametropia in Ya'an People's Hospital between March 2020 and January 2022. According to the diopter and axial length (AL), the patients were divided into an emmetropia group (32 cases), a low-to-moderate myopia group (40 cases), and a high myopia group (40 cases). Relevant data were collected and analyzed.

RESULTS

The AST of the four diameter lines was highest at the scleral process and measured. The results, in descending order, were as follows: temporal side (716.45 ± 65.55 μm), lower side (692.32 ± 74.76 μm), nasal side (671.54 ± 61.76 μm), and superior side (550.76 ± 51.34 μm). There was a correlation between the AL and the average AST of the four diameter lines. The correlations, from highest to lowest, were as follows: the mean AST of the nasal side (r = -0.455, P < 0.001), the mean AST of the upper side (r = -0.431, P < 0.001), the mean AST of the lower side (r = -0.402, P < 0.001) and the mean AST of the temporal side (r = -0.363, P < 0.001). Age was associated with the average AST of the upper, nasal, and temporal sides. The correlations, from highest to lowest, were as follows: the average AST of the upper side (r = 0.545, P < 0.001), the average AST of the temporal side (r = 0.422, P < 0.001), and the average AST of the nasal side (r = 0.411, P < 0.001). There were significant differences in AST among the three groups at 0, 1, 2, 3, 4, 5, and 6 mm from the scleral bulge (P < 0.05). AST was positively correlated with age and negatively correlated with AL (R2= 0.432, F = 231.73, P < 0.05).

CONCLUSION

The thickness of the sclera changed with the AL and measurement position. AST was negatively correlated with the AL and positively correlated with age. Compared with emmetropia and low-to-moderate myopia, the anterior sclera in cases of high myopia was thinner. Myopia affects not only the thickness of the posterior sclera but also the AST.

The Contribution of the Limbus and Collagen Fibrils to Corneal Biomechanical Properties: Estimation of the Low-Strain In Vivo Elastic Modulus and Tissue Strain

We have compared the biomechanical properties of human and porcine corneas using vibrational optical coherence tomography (VOCT). The elastic modulus of the cornea has been previously reported in the literature to vary from about several kPa to more than several GPa based on the results of different techniques. In addition, the formation of corneal cones near the central cornea in keratoconus has been observed in the clinic. Measurements of the resonant frequency and morphology of human and porcine corneas were used to evaluate the role of the limbus in corneal stabilization, the effect of Bowman's layer, and the effect of collagen content on the low-strain corneal biomechanics. The results of these studies indicate that limbus stability plays an important anatomic role in preventing folding, corneal slippage, and cone formation. Machine learning studies of both human and porcine corneas indicate that Bowman's membrane, like that of the collagen fibrils found in the anterior corneal stroma, contributes to the 110-120 Hz resonant frequency peak. Finite element and SOLIDWORKS models of normal and keratoconus corneas suggest that the deformation of the cornea is the highest at the central zone and is higher in keratoconus corneas compared to normal controls. VOCT results suggest that although collagen fibril slippage occurs first at the limbus, cone formation in keratoconus occurs centrally/paracentrally, where stress concentration and deformation due to intraocular forces are the highest. Cone formation occurs at the points of maximum curvature. Results of these studies indicate the elastic modulus of cornea fibrillar collagen dictates the corneal elastic modulus at low strains. These results suggest that tension in the cornea at the limbus results in deformation into the low modulus region of the J-shaped stress-strain curve, resulting in an in vivo strain of less than about 10%. We propose that tension in the cornea provides a baseline force that regulates corneal epithelial regeneration as well as corneal lamellae composition and matrix turnover.

Form-deprivation myopia promotes sclera M2-type macrophages polarization in mice

PURPOSE

To explore the phenotype of sclera macrophages in form-deprivation (FD) myopia mice and the effects of M2 macrophage in FD myopia development.

METHODS

C57BL/6 mice were under 2 weeks of unilateral FD treatment. and they were separated into two groups, including an intraperitoneally injected(IP) vehicle group and Panobinostat (LBH589) (10 mg/kg per body weight) treatment group. All biometric parameters were measured before and after treatments, and the type and density of sclera macrophages were identified by immunofluorescence and RT-qPCR. In vitro, we analyzed the M2 macrophage and primary human sclera fibroblast (HSF) co-culture system by using the transcriptome sequencing method. Gene ontology (GO) and KEGG enrichment analyses were used to pinpoint the biological functions and pathways associated with the identified Differentially Expressed Genes (DEGs). The hub genes were investigated using the STRING database and Cytoscape software and were confirmed using RT-qPCR.

RESULTS

We found that the M2-type sclera macrophage density and expression increased in FD-treated eyes. The results showed that LBH589 inhibited the M2 macrophage polarization, and reduced FDM development. GO and KEGG analyses revealed that the DEGs were predominantly involved in the synthesis and breakdown of the extracellular matrix (ECM), as well as in pathways related to ECM-receptor interaction and the PI3K-Akt signaling pathway. Five hub genes (FN-1, MMP-2, COL1A1, CD44, and IL6) were identified, and RT-qPCR validated the variation in expression levels among these genes.

CONCLUSION

M2 macrophage polarization occurred in the sclera in FDM mice. Panobinostat-mediated inhibition of M2 macrophage polarization may decrease FDM progression, as M2 macrophages are crucial in controlling ECM remodeling by HSFs.

Clinical application and outcome of Tenon's patch graft: A comprehensive review

Corneal perforations are potentially sight-threatening conditions if not promptly treated. Management depends on the size, location, cause, and severity of the perforation. Various methods, including tissue adhesives, amniotic membrane grafting (AMG), and keratoplasty, are available. However, the limited availability of donor tissue in emergencies poses a significant challenge. Recently, Tenon's patch grafting (TPG) has emerged as a promising treatment option due to its autologous nature, availability, and lack of immunogenicity. This review provides a comprehensive overview of various aspects of TPG, along with relevant images. A literature search using keywords such as "Tenon's patch graft," "Tenon's capsule," "corneal patch graft," "amniotic membrane," and "corneal perforations" yielded 37 articles, included in this review. TPG is suitable for cases involving corneal tissue degradation leading to perforation, impending perforation, or descemetocele, with lesion sizes ranging from 2 to 6 mm. For larger perforations, the procedure may be modified by combining it with AMG or tissue adhesives. Postoperatively, the graft undergoes characteristic changes, including epithelialization and collagen deposition, resulting in the formation of a thick scar. Complications such as delayed epithelialization, wound leaks, and graft dehiscence can occur. High success rates have been reported, ranging from 74% to 87%. However, TPG may result in suboptimal visual outcomes, particularly when the graft is centrally located, necessitating future keratoplasty for visual rehabilitation. Overall, TPG is a safe and cost-effective technique for restoring structural integrity in corneal thinning disorders and perforations, especially in emergency settings when donor tissue is unavailable.

High correlated color temperature white light-emitting diodes disrupt refractive development in guinea pigs

Ubiquitous white light-emitting diodes (LEDs) possess optical properties that differ from those of natural light. This difference can impact visual perception and biological functions, thus potentially affecting eye health. Myopia, which leads to visual impairments and potentially irreversible vision loss or blindness, is the most prevalent refractive error worldwide. Ambient light has been found to be a significant factor in refractive development. The overlap between the commonly utilized of white LEDs and the rapid increase in the prevalence of myopia raises suspicions that white LEDs may represent hidden visual cues. To clarify the potential effects of white LEDs on refractive development, we exposed guinea pigs to different forms of artificial lighting over a period of eight weeks. We found that exposure to white LEDs with a high correlated color temperature (CCT) of approximately 5000 K can induce significant myopic shifts in guinea pigs, along with a decrease in collagen accumulation in the sclera. Additionally, this exposure was found to significantly reduce choroidal tissue thickness in guinea pigs. Our study findings indicate that high CCT white LEDs disrupt refractive development in guinea pigs. These results suggest that high CCT white LEDs might similarly affect refractive development in humans, highlighting the need for further clinical investigation.

Quercetin Alleviates Scleral Remodeling Through Inhibiting the PERK-EIF2α Axis in Experiment Myopia

Purpose

This study aims to investigate the effect of quercetin (QUE) on scleral remodeling by inhibiting the PERK-EIF2α signaling pathway and to evaluate its potential role in slowing myopia.

Methods

Lens-induced myopia (LIM) guinea pigs were obtained and treated with QUE. After 4 and 6 weeks of treatments, ocular biological measurements were conducted. Hematoxylin and eosin (H&E) staining was used to observe the changes in scleral morphology and thickness, and Masson staining was used to examine scleral collagen fiber arrangement. Quantitative PCR (qPCR) and Western bolt were utilized to detect the mRNA and protein expression of PERK, EIF2α, MMP-2, TIMP-2, and collagen I in the scleral tissues. Calcium ion flow in each group was measured using noninvasive micro-test technology, and reactive oxygen species levels were detected by flow cytometry.

Results

Compared with the LIM group, the ocular measurements showed that the refractive errors and axial length of the eyes were significantly reduced in the LIM + QUE group (P < 0.01). H&E and Masson staining showed that sclera in the LIM + QUE group was thickened, collagen was dense, and the fiber gap was reduced. In the LIM + QUE group, the expression levels of PERK, EIF2α, and MMP-2 were decreased, whereas the expression levels of TIMP-2 and collagen I were increased. Calcium release and reactive oxygen species (ROS) in the LIM + QUE group were decreased.

Conclusions

Quercetin ameliorates scleral remodeling in myopic guinea pigs by inhibiting the PERK-EIF2α signaling pathway, thereby alleviating the progression of myopia. These findings provide new experimental evidence for the potential application of quercetin in myopia prevention and treatment.

Comparing IOP-Induced Scleral Deformations in the Myopic and Myopic Glaucoma Spectrums

Purpose

To compare changes in macular curvature following acute IOP elevation across a range of myopic conditions.

Methods

We studied 328 eyes from 184 subjects, comprising 32 emmetropic controls (between +2.75 and -2.75 diopters), 50 eyes with high myopia (<-5 diopters; HM), 108 highly myopic with glaucoma (HMG) and 105 pathologic myopia (PM) eyes, and 33 PM with staphyloma (PM+S) eyes. For each eye, we imaged the macula using optical coherence tomography (OCT) under the baseline condition and under acute IOP elevation (to ∼40 mm Hg) achieved through ophthalmodynamometry. We manually aligned the scans (baseline and IOP elevation) using three vascular landmarks in the macula tissue. We then automatically segmented the sclera and the choroid tissues using a deep learning algorithm and extracted the sclera-choroid interface. We calculated the macula curvatures, determined by the radius of curvature of the sclera-choroid interface in the nasal-temporal and superior-inferior direction. Differences in macula curvatures between baseline and elevated IOP scans were calculated at corresponding locations, and the mean curvature difference was reported for each eye.

Results

IOP elevation resulted in a significantly higher macula curvature change along the nasal-temporal direction in the PM+S (13.5 ± 8.2 × 10-5 µm-1), PM (9.0 ± 7.9 × 10-5 µm-1), and HMG (5.2 ± 5.1 × 10-5 µm-1) eyes as compared to HM (3.1 ± 2.7 × 10-5 µm-1) eyes (all P < 0.05). Interestingly, HM and HMG eyes had the same curvature change in the nasal-temporal direction as emmetropic control eyes (4.2 ± 4.3 × 10-5 µm-1).

Conclusions

Our findings indicate that the macula in HMG, PM, and PM+S eyes showed greater curvature changes under IOP elevation compared to HM and emmetropic eyes. These preliminary results suggest that HM eyes with conditions such as glaucoma or staphyloma are more sensitive to acute IOP elevation.

In-vivo high-frequency quantitative ultrasound-derived parameters of the anterior sclera correlated with level of myopia and presence of staphyloma

BACKGROUND

A high-frequency point-of-care (POC) ultrasound instrument was used to evaluate the microstructural and biomechanical properties of the anterior sclera in vivo using parameters computed from quantitative ultrasound (QUS) methods.

METHODS

In this cross-sectional study, both eyes of 85 enrolled patients were scanned with the POC instrument and ultrasound data were processed to obtain QUS parameters. Pearson correlation and multi-linear regression were used to identify relationships between QUS parameters and refractive error (RE) or axial length. After categorising eyes based on RE, binary support vector machine (SVM) classifiers were trained using the QUS or ophthalmic parameters (anterior chamber depth, central corneal thickness, corneal power, and intraocular pressure) to classify each eye. Classifier performance was evaluated by computing the area under the receiver-operating characteristic curve (AUC).

RESULTS

Individual QUS parameters correlated with RE and axial length (p < 0.05). Multi-linear regression revealed significant correlation between the set of QUS parameters and both RE (R = 0.49, p < 0.001) and axial length (R = 0.46, p = 0.001). Classifiers trained with QUS parameters achieved higher AUC (𝑝 = 0.06) for identifying myopic eyes (AUC = 0.71) compared to classifiers trained with ophthalmic parameters (AUC = 0.63). QUS-based classifiers attained the highest AUC when identifying highly myopic eyes (AUC = 0.77).

CONCLUSIONS

QUS parameters correlate with progressing myopia and may be indicative of myopia-induced microstructural and biomechanical changes in the anterior sclera. These methods may provide critical clinical information complementary to standard ophthalmic measurements for predicting myopia progression and risk assessment for posterior staphyloma formation.

Anterior scleral thickness in Marfan syndrome: A quantitative analysis

PURPOSE

To investigate the anterior scleral thickness (AST) in patients with Marfan syndrome (MFS).

METHODS

A prospective, cross-sectional study was conducted at the Department of Ophthalmology, Ghent University Hospital, Ghent, including patients with a genetically confirmed clinical diagnosis of MFS and age-, gender- and axial length-matched controls. Subjects with known corneal, conjunctival or scleral pathology and a history of ocular surgery, including pars plana vitrectomy, recent contact lens use or high-grade astigmatism were excluded. Subjects underwent non-cycloplegic autorefraction, Scheimpflug-based corneal tomography, axial length measurement and spectral-domain optical coherence tomography (OCT). AST was manually measured at 1 mm (AST1), 2 mm (AST2) and 3 mm (AST3) from the scleral spur, temporally and nasally.

RESULTS

A total of 56 subjects (28 subjects in the MFS group and 28 matched subjects in the control group) were included in this study. In patients with MFS, AST was significantly reduced compared to matched controls, both overall and at every analysed measuring point in the nasal and temporal areas (p < 0.001). Central corneal thickness (CCT) and mean keratometry (Kmean) values were significantly lower in patients with MFS (p < 0.05). A positive correlation was found between nasal AST and CCT in patients with MFS. No correlation was found between AST and Kmean or between AST and axial length. In patients with MFS with ectopia lentis, compared to those without, temporal AST3 was significantly lower (p < 0.05). AST was significantly lower in patients with MFS harbouring a variant predicted to cause haploinsufficiency compared to those with a variant expected to lead to a dominant negative effect for both nasal and temporal measurements.

CONCLUSION

Based on anterior segment OCT measurements, AST of patients with MFS is significantly lower compared to matched controls.

Relationship between corneal hysteresis and the site of damage to peripapillary retinal nerve fibre layer thickness in open-angle glaucoma

Corneal hysteresis (CH) is associated with glaucomatous structural changes. We retrospectively investigated the association between CH and the regional circumpapillary retinal nerve fibre layer thickness (cpRNFLT) in 419 eyes of 419 patients with normal-tension glaucoma (NTG) and primary open-angle glaucoma (POAG). CH was used as the explanatory variable, and cpRNFLT (total and quadrant) was used as the dependent variable. Standardized β coefficients were compared both overall and between the NTG and POAG groups. Multiple regression analysis with CH as the explanatory variable and cpRNFLT parameters as the dependent variables suggested that even after adjusting for age, sex, intraocular pressure (IOP), axial length, and central corneal thickness, all areas of the cpRNFLT were significantly associated with CH, except for the nasal quadrant. In the stratified analysis by glaucoma type, a positive relationship between CH and regional cpRNFLT tended to be maintained in the NTG group but not in the POAG group (P = 0.060 for interaction). Additionally, in the NTG group, the CH-inferior cpRNFLT relationship was particularly strong in the less-IOP fluctuation group. These results suggest that CH may be a potential predictor of anatomical vulnerability around the optic nerve, particularly enhancing the inferior regions of NTG.

Assessment of the Corneal Biomechanical Features of Sturge-Weber Syndrome Using Dynamic Ultrahigh-speed Scheimpflug Imaging

PURPOSE

To evaluate the corneal biomechanical characteristics of eyes with Sturge-Weber syndrome (SWS) secondary glaucoma (SSG) by analyzing corneal biomechanical parameters obtained using the Corneal Visualization Scheimpflug Technology instrument (Corvis ST).

METHODS

In patients with SWS, eyes affected by SSG were designated as the SSG group while the contralateral eyes were designated as the SWS contralateral group (SC group). Patients from the myopia clinic served as the control group. Dynamic corneal response parameters (DCRs) including the stress-strain index (SSI)-a critical material stiffness parameter that excludes interference from IOP and central corneal thickness (CCT)-were analyzed.

RESULTS

For CCT, no significant difference was observed between the SSG and SC groups. However, significant differences were found between the SSG and control groups and between the SC and control groups. Parameters such as HC Time, A1 Deformation Amp., A2 Deformation Amp., length of Whole Eye Movement (WEM), DA Ratio Max (2 mm), PachySlope, DA Ratio Max (1 mm), and ARTh showed significant differences between the SSG group and control group. In the SSG group, 4 of night eyes had an SSI of less than 0.85.

CONCLUSIONS

Some DCRs indicated a stiffer cornea in the SSG group, possibly due to a thicker cornea in this group. On analyzing SSI, it was found that corneal material properties change, becoming less stiff in some of the patients with SSG. In conclusion, our study provides a preliminary exploration of the biomechanical properties of SWS secondary glaucoma.

Revolutionizing Eye Care: Exploring the Potential of Microneedle Drug Delivery

Microneedle technology revolutionizes ocular drug delivery by addressing challenges in treating ocular diseases. This review explores its potential impact, recent advancements, and clinical uses. This minimally invasive technique offers precise control of drug delivery to the eye, with various microneedle types showing the potential to penetrate barriers in the cornea and sclera, ensuring effective drug delivery. Recent advancements have improved safety and efficacy, offering sustained and controlled drug delivery for conditions like age-related macular degeneration and glaucoma. While promising, challenges such as regulatory barriers and long-term biocompatibility persist. Overcoming these through interdisciplinary research is crucial. Ultimately, microneedle drug delivery presents a revolutionary method with the potential to significantly enhance ocular disease treatment, marking a new era in eye care.

Molecular mechanism of hypoxia and alpha-ketoglutaric acid on collagen expression in scleral fibroblasts

AIM

To investigate the molecular mechanisms underlying the influence of hypoxia and alpha-ketoglutaric acid (α-KG) on scleral collagen expression.

METHODS

Meta-analysis and clinical statistics were used to prove the changes in choroidal thickness (ChT) during myopia. The establishment of a hypoxic myopia model (HYP) for rabbit scleral fibroblasts through hypoxic culture and the effects of hypoxia and α-KG on collagen expression were demonstrated by Sirius red staining. Transcriptome analysis was used to verify the genes and pathways that hypoxia and α-KG affect collagen expression. Finally, real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) was used for reverse verification.

RESULTS

Meta-analysis results aligned with clinical statistics, revealing a thinning of ChT, leading to scleral hypoxia. Sirius red staining indicated lower collagen expression in the HYP group and higher collagen expression in the HYP+α-KG group, showed that hypoxia reduced collagen expression in scleral fibroblasts, while α-KG can elevated collagen expression under HYP conditions. Transcriptome analysis unveiled the related genes and signaling pathways of hypoxia and α-KG affect scleral collagen expression and the results were verified by RT-qPCR.

CONCLUSION

The potential molecular mechanisms through which hypoxia and α-KG influencing myopia is unraveled and three novel genes TLCD4, TBC1D4, and EPHX3 are identified. These findings provide a new perspective on the prevention and treatment of myopia via regulating collagen expression.

Comparing continuum and direct fiber models of soft tissues: An ocular biomechanics example reveals that continuum models may artificially disrupt the strains at both the tissue and fiber levels

Collagen fibers are the main load-bearing component of soft tissues but difficult to incorporate into models. Whilst simplified homogenization models suffice for some applications, a thorough mechanistic understanding requires accurate prediction of fiber behavior, including both detailed fiber-level strains and long-distance transmission. Our goal was to compare the performance of a continuum model of the optic nerve head (ONH) built using conventional techniques with a fiber model we recently introduced which explicitly incorporates the complex 3D organization and interaction of collagen fiber bundles [1]. To ensure a fair comparison, we constructed the continuum model with identical geometrical, structural, and boundary specifications as for the fiber model. We found that: 1) although both models accurately matched the intraocular pressure (IOP)-induced globally averaged displacement responses observed in experiments, they diverged significantly in their ability to replicate specific 3D tissue-level strain patterns. Notably, the fiber model faithfully replicated the experimentally observed depth-dependent variability of radial strain, the ring-like pattern of meridional strain, and the radial pattern of circumferential strain, whereas the continuum model failed to do so; 2) the continuum model disrupted the strain transmission along each fiber, a feature captured well by the fiber model. These results demonstrate limitations of the conventional continuum models that rely on homogenization and affine deformation assumptions, which render them incapable of capturing some complex tissue-level and fiber-level deformations. Our results show that the strengths of explicit fiber modeling help capture intricate ONH biomechanics. They potentially also help modeling other fibrous tissues. STATEMENT OF SIGNIFICANCE: Understanding the mechanics of fibrous tissues is crucial for advancing knowledge of various diseases. This study uses the ONH as a test case to compare conventional continuum models with fiber models that explicitly account for the complex fiber structure. We found that the fiber model captured better the biomechanical behaviors at both the tissue level and the fiber level. The insights gained from this study demonstrate the significant potential of fiber models to advance our understanding of not only glaucoma pathophysiology but also other conditions involving fibrous soft tissues. This can contribute to the development of therapeutic strategies across a wide range of applications.

Relationship between Choroidal Thickness and Anterior Scleral Thickness in Patients with Keratoconus

PURPOSE

To evaluate the relationship between choroidal thickness (CT) and anterior scleral thickness (AST) in patients with subclinical keratoconus (SKC) and established keratoconus (KC).

METHODS

This single-center prospective case-control study included 97 eyes of 97 patients: 44 KC eyes, 14 SKC eyes, and 39 age- and axial length (AL)-matched healthy eyes. Using swept-source optical coherence tomography, the AST was manually measured in four directions and the CT was obtained automatically from the Early Treatment Diabetic Retinopathy Study (ETDRS) grid. Principal component analysis (PCA) was used to linearly reduce the dimensionality of nine CT inputs to one significant component, CT1. A multivariate model was created to evaluate the association between CT1, AST, and several ocular parameters in SKC and KC patients. Partial correlation was then performed to adjust the confounding factors and to examine the effect of AST on CT1.

RESULTS

The PCA showed that CT1 accounts for 86.54% of the total variance in the nine original CTs of the ETDRS grid. The CT1 model was associated with age, AL, and AST in the superior meridian in SKC eyes, whereas in KC eyes, it was correlated with gender, age, AL, and AST in the inferior meridian (p < 0.001). The partial correlation between CT1 and AST in the superior zone was found to be significant, positive, and strong in SKC eyes (r = 0.79, p = 0.019), whereas a significant, positive, and moderate correlation between CT1 and AST at the inferior zone (r = 0.41, p = 0.017) was observed in KC eyes.

CONCLUSIONS

Choroidal tissue was significantly correlated with the anterior sclera across the vertical meridian. This relationship was observed over the superior sclera in SKC eyes, whereas in established KC, it was over the inferior sclera. These results reveal new insights regarding the interactions between the anterior and posterior structures of the KC eyes and confirm the enigma of the pathophysiology of KC.

Dynamic BMP gene expression regulation in chick RPE during recovery from short term optical defocus and form-deprivation

PURPOSE

This study investigated the differential gene expression of BMPs in chick retinal pigment epithelium (RPE) during recovery from short term exposure to optical defocus and form-deprivation (FD) treatments.

METHODS

14-day old White-Leghorn chicks wore either monocular +10 or -10 D lenses, or diffusers for 2 or 48 h, after which eyes were allowed unobstructed vision for up to 96 h. Over this recovery period, refractive errors and choroidal thickness (ChT) were tracked using retinoscopy and high-frequency A-scan ultrasonography. Real-time PCR was used to examine the expression of BMP2, 4, and 7 genes in RPE samples collected 0, 15 min, 2, 24, 48, and 96 h after the termination of treatments. Expression levels in treated eyes and their contralateral control eyes were compared.

RESULTS

After the termination of the lens and diffuser treatments, eyes gradually recovered from induced shifts in refractive error. With all three treatments, ChT changes reached statistical significance after 48 h of treatment, be it thinning with the -10 D lens and diffuser treatments (-0.06 ± 0.03mm, p < 0.05; -0.11 ± 0.04 mm, p < 0.05, resp.), or thickening with the +10 D lens (0.31 ± 0.04 mm, p < 0.001). BMP2 gene expression was rapidly upregulated in eyes wearing the +10 D lens, being statistical significance after 2 h, as well as 48 h of treatment. With the 2 h treatment, the latter gene expression pattern persisted for 15 min into the recovery period, before decreasing to the same level as that of contralateral control eyes, with a short-lived rebound, i.e., upregulation, 24 h into the recovery period. With the longer, 48 h treatment, BMP2 gene expression decreased more gradually, from 739 ± 121% at the end of the treatment period, to 72 ± 14% after 48 h of recovery. Two and 48 h of both -10 D and FD treatments resulted in BMP2 gene expression downregulation, with the time taken for gene expression levels to fully recover varying with the duration of initial treatments. In both cases, BMP2 gene expression downregulation persisted for 15 min into the recovery period, but reversed to upregulation by 2 h. Similar gene expression patterns were also observed for BMP4, although the changes were smaller.

CONCLUSIONS

The observed changes in BMP gene expression in chick RPE imply dynamic, albeit complex regulation, with the duration of exposure and recovery being critical variables for all three types of visual manipulations. This study provides further evidence for a role of the RPE as an important signal relay linking the retina to the choroid and sclera in eye growth regulation.

Biomechanical changes occur in myopic choroidal stroma and mirror those in the adjacent sclera

Retina-derived growth signals relayed from the choroid to the sclera cause remodeling of the extracellular scleral matrix, resulting in myopic ocular elongation. However, to the best of our knowledge, no studies have assessed changes in choroidal stromal biomechanical properties during myopia progression. Here we utilized 7 µm-resolution scanning acoustic microscopy (SAM) to assess biomechanical properties (bulk modulus (K) and mass density (rho)) of choroidal stroma from guinea pig eyes with form-deprivation (FD) induced myopia. The choroidal stroma had considerable intrinsic strength arising from its biomechanical properties and these were differentially affected by myopia in central and peripheral regions. Choroidal stromal biomechanical values were also highly correlated with those in adjacent scleral regions, and the choroidal stromal-scleral association was stronger in myopic eyes. Biomechanical changes observed in the choroidal stroma of myopic eyes were mirrored to those observed in the adjacent sclera. These findings suggest that choroidal stromal remodeling may accompany myopia and open the door to the source of the signals that cause scleral remodeling in myopia.

Effects of Genipin Crosslinking of Porcine Perilimbal Sclera on Mechanical Properties and Intraocular Pressure

The mechanical properties of sclera play an important role in ocular functions, protection, and disease. Modulating the sclera's properties by exogenous crosslinking offers a way to expand the tissue's range of properties for study of the possible influences on the eye's behavior and diseases such as glaucoma and myopia. The focus of this work was to evaluate the effects of genipin crosslinking targeting the porcine perilimbal sclera (PLS) since the stiffness of this tissue was previously found in a number of studies to influence the eye's intraocular pressure (IOP). The work includes experiments on tensile test specimens and whole globes. The specimen tests showed decreased strain-rate dependence and increased relaxation stress due to the cross-linker. Whole globe perfusion experiments demonstrated that eyes treated with genipin in the perilimbal region had increased IOPs compared to the control globes. Migration of the cross-linker from the target tissue to other tissues is a confounding factor in whole globe, biomechanical measurements, with crosslinking. A novel quantitative genipin assay of the trabecular meshwork (TM) was developed to exclude globes where the TM was inadvertently crosslinked. The perfusion study, therefore, suggests that elevated stiffness of the PLS can significantly increase IOP apart from effects of the TM in the porcine eye. These results demonstrate the importance of PLS biomechanics in aqueous outflow regulation and support additional investigations into the distal outflow pathways as a key source of outflow resistance.

Capturing sclera anisotropy using direct collagen fiber models. Linking microstructure to macroscopic mechanical properties

Because of the crucial role of collagen fibers on soft tissue mechanics, there is great interest in techniques to incorporate them in computational models. Recently we introduced a direct fiber modeling approach for sclera based on representing the long-interwoven fibers. Our method differs from the conventional continuum approach to modeling sclera that homogenizes the fibers and describes them as statistical distributions for each element. At large scale our method captured gross collagen fiber bundle architecture from histology and experimental intraocular pressure-induced deformations. At small scale, a direct fiber model of a sclera sample reproduced equi-biaxial experimental behavior from the literature. In this study our goal was a much more challenging task for the direct fiber modeling: to capture specimen-specific 3D fiber architecture and anisotropic mechanics of four sclera samples tested under equibiaxial and four non-equibiaxial loadings. Samples of sclera from three eyes were isolated and tested in five biaxial loadings following an approach previously reported. Using microstructural architecture from polarized light microscopy we then created specimen-specific direct fiber models. Model fiber orientations agreed well with the histological information (adjusted R2's>0.89). Through an inverse-fitting process we determined model characteristics, including specimen-specific fiber mechanical properties to match equibiaxial loading. Interestingly, the equibiaxial properties also reproduced all the non-equibiaxial behaviors. These results indicate that the direct fiber modeling method naturally accounted for tissue anisotropy within its fiber structure. Direct fiber modeling is therefore a promising approach to understand how macroscopic behavior arises from microstructure.

Influence of Contact Lens Parameters on Cornea: Biomechanical Analysis

This study presents a finite element analysis to model ocular biomechanics and the interactions between the human eye and contact lenses in the closed-eye condition. The closed-eye state, where the eyelids are fully shut, presents challenges for experimental measurements due to the invasive nature of accessing and analysing the contact lens and corneal interface, making simulation tools valuable for accurate characterisation. The primary objective of this study was to examine how CLs fold and twist and their impact on the cornea when the eye is closed. The secondary aim of this study was to assess how crucial contact lens parameters (Young's modulus, base curve, and diameter) influence corneal stress distribution and the overall fit of the lens on the eye. The findings show that increasing Young's modulus significantly reduces corneal stress and promotes uniform stress distribution, making it the most influential factor for wearer comfort and safety. While base curve and diameter variations primarily affect contact area, their impact on stress distribution is minimal. This research provides insights for improving contact lens design and enhancing safety for contact lens wearers.

Comparing continuum and direct fiber models of soft tissues. An ocular biomechanics example reveals that continuum models may artificially disrupt the strains at both the tissue and fiber levels

Collagen fibers are the main load-bearing component of soft tissues but difficult to incorporate into models. Whilst simplified homogenization models suffice for some applications, a thorough mechanistic understanding requires accurate prediction of fiber behavior, including both detailed fiber-level strains and long-distance transmission. Our goal was to compare the performance of a continuum model of the optic nerve head (ONH) built using conventional techniques with a fiber model we recently introduced which explicitly incorporates the complex 3D organization and interaction of collagen fiber bundles [1]. To ensure a fair comparison, we constructed the continuum model with identical geometrical, structural, and boundary specifications as for the fiber model. We found that: 1) although both models accurately matched the intraocular pressure (IOP)-induced globally averaged displacement responses observed in experiments, they diverged significantly in their ability to replicate specific 3D tissue-level strain patterns. Notably, the fiber model faithfully replicated the experimentally observed depth-dependent variability of radial strain, the ring-like pattern of meridional strain, and the radial pattern of circumferential strain, whereas the continuum model failed to do so; 2) the continuum model disrupted the strain transmission along each fiber, a feature captured well by the fiber model. These results demonstrate limitations of the conventional continuum models that rely on homogenization and affine deformation assumptions, which render them incapable of capturing some complex tissue-level and fiber-level deformations. Our results show that the strengths of explicit fiber modeling help capture intricate ONH biomechanics. They potentially also help modeling other fibrous tissues.

Revealing regional variations in scleral shear modulus in a rabbit eye model using multi-directional ultrasound optical coherence elastography

The mechanical properties of the sclera play a critical role in supporting the ocular structure and maintaining its shape. However, non-invasive measurements to quantify scleral biomechanics remain challenging. Recently introduced multi-directional optical coherence elastography (OCE) combined with an air-coupled ultrasound transducer for excitation of elastic surface waves was used to estimate phase speed and shear modulus in ex vivo rabbit globes (n = 7). The scleral phase speed (12.1 ± 3.2 m/s) was directional-dependent and higher than for corneal tissue (5.9 ± 1.4 m/s). In the tested locations, the sclera proved to be more anisotropic than the cornea by a factor of 11 in the maximum of modified planar anisotropy coefficient. The scleral shear moduli, estimated using a modified Rayleigh-Lamb wave model, showed significantly higher values in the circumferential direction (65.4 ± 31.9 kPa) than in meridional (22.5 ± 7.2 kPa); and in the anterior zone (27.3 ± 9.3 kPa) than in the posterior zone (17.8 ± 7.4 kPa). The multi-directional scanning approach allowed both quantification and radial mapping of estimated parameters within a single measurement. The results indicate that multi-directional OCE provides a valuable non-invasive assessment of scleral tissue properties that may be useful in the development of improved ocular models, the evaluation of potential myopia treatment strategies, and disease characterization and monitoring.

Identification of LRRC46 as a novel candidate gene for high myopia

High myopia (HM) is the primary cause of blindness, with the microstructural organization and composition of collagenous fibers in the cornea and sclera playing a crucial role in the biomechanical behavior of these tissues. In a previously reported myopic linkage region, MYP5 (17q21-22), a potential candidate gene, LRRC46 (c.C235T, p.Q79X), was identified in a large Han Chinese pedigree. LRRC46 is expressed in various eye tissues in humans and mice, including the retina, cornea, and sclera. In subsequent cell experiments, the mutation (c.C235T) decreased the expression of LRRC46 protein in human corneal epithelial cells (HCE-T). Further investigation revealed that Lrrc46-/- mice (KO) exhibited a classical myopia phenotype. The thickness of the cornea and sclera in KO mice became thinner and more pronounced with age, the activity of limbal stem cells decreased, and microstructural changes were observed in the fibroblasts of the sclera and cornea. We performed RNA-seq on scleral and corneal tissues of KO and normal control wild-type (WT) mice, which indicated a significant downregulation of the collagen synthesis-related pathway (extracellular matrix, ECM) in KO mice. Subsequent in vitro studies further indicated that LRRC46, a member of the important LRR protein family, primarily affected the formation of collagens. This study suggested that LRRC46 is a novel candidate gene for HM, influencing collagen protein VIII (Col8a1) formation in the eye and gradually altering the biomechanical structure of the cornea and sclera, thereby promoting the occurrence and development of HM.

Contact lens fitting and changes in the tear film dynamics: mathematical and computational models review

PURPOSE

This review explores mathematical models, blinking characterization, and non-invasive techniques to enhance understanding and refine clinical interventions for ocular conditions, particularly for contact lens wear.

METHODS

The review evaluates mathematical models in tear film dynamics and their limitations, discusses contact lens wear models, and highlights computational mechanical models. It also explores computational techniques, customization of models based on individual blinking dynamics, and non-invasive diagnostic tools like high-speed cameras and advanced imaging technologies.

RESULTS

Mathematical models provide insights into tear film dynamics but face challenges due to simplifications. Contact lens wear models reveal complex ocular physiology and design aspects, aiding in lens development. Computational mechanical models explore eye biomechanics, often integrating tear film dynamics into a Multiphysics framework. While different computational techniques have their advantages and disadvantages, non-invasive tools like OCT and thermal imaging play a crucial role in customizing these Multiphysics models, particularly for contact lens wearers.

CONCLUSION

Recent advancements in mathematical modeling and non-invasive tools have revolutionized ocular health research, enabling personalized approaches. The review underscores the importance of interdisciplinary exploration in the Multiphysics approach involving tear film dynamics and biomechanics for contact lens wearers, promoting advancements in eye care and broader ocular health research.

Construction of glaucoma model and comparing eyeball enlargement with myopia in Guinea pig

This study aimed to develop and evaluate a guinea pig model for glaucoma, comparing resultant eyeball enlargement with an existing myopia model. Thirty guinea pigs underwent intracameral injection of magnetic microspheres to induce chronic ocular hypertension (COH). Intraocular pressure (IOP) was systematically monitored, revealing a successful induction of COH in 73.33% of the guinea pigs. The mean IOP increased from a baseline of 18.04 ± 1.33 mmHg, reaching a peak at week 3 (36.31 ± 6.13 mmHg) and remaining elevated for at least 7 weeks. All data are presented as mean ± standard deviation of the mean. Subsequently, detailed assessments were conducted to validate the established glaucoma model. Immunofluorescent staining demonstrated a significant decrease in the density of retinal ganglion cells (RGC) in the glaucoma group. Optic disc excavation and notable thinning of the lamina cribrosa (LC) were observed. The quantity of optic nerve ax·ons in glaucoma group gradually decreased from baseline (44553 ± 3608/mm2) to week 4 (28687 ± 2071/mm2) and week 8 (17977 ± 3697/mm2). Moreover, regarding the global enlargement of eyeballs, both the transverse and longitudinal axis in glaucomatous eyes were found to be significantly larger than that in myopic eyes, particularly in the anterior chamber depth (1.758 ± 0.113 mm vs. 1.151 ± 0.046 mm). These findings indicate distinct patterns of structural changes associated with glaucoma and myopia in the guinea pig model. This guinea pig model holds promise for future research aimed at exploring biomechanical mechanisms, therapeutic interventions, and advancing our understanding of the relationship between glaucoma and myopia.

Differential Functional Changes in Visual Performance during Acute Exposure to Microgravity Analogue and Their Potential Links with Spaceflight-Associated Neuro-Ocular Syndrome

BACKGROUND

Spaceflight-Associated Neuro-Ocular Syndrome (SANS) is a complex pathology threatening the health of astronauts, with incompletely understood causes and no current specific functional diagnostic or screening test. We investigated the use of the differential performance of the visual system (central vs. perimacular visual function) as a candidate marker of SANS-related pathology in a ground-based microgravity analogue.

METHODS

We used a simple reaction time (SRT) task to visual stimuli, presented in the central and perimacular field of view, as a measure of the overall performance of the visual function, during acute settings (first 10 min) of vertical, bed rest (BR), -6°, and -15° head-down tilt (HDT) presentations in healthy participants (n = 8). We built dose-response models linking the gravitational component to SRT distribution parameters in the central vs. perimacular areas.

RESULTS

Acute exposure to microgravity induces detectable changes between SRT distributions in the perimacular vs. central retina (increased mean, standard deviation, and tau component of the ex-Gaussian function) in HDT compared with vertical presentation.

CONCLUSIONS

Functional testing of the perimacular retina might be beneficial for the earlier detection of SANS-related ailments in addition to regular testing of the central vision. Future diagnostic tests should consider the investigation of the extra-macular areas, particularly towards the optic disc.

Collagen is crucial target protein for scleral remodeling and biomechanical change in myopia progression and control

In recent decades, the prevalence of myopia has been on the rise globally, attributed to changes in living environments and lifestyles. This increase in myopia has become a significant public health concern. High myopia can result in thinning of the sclera and localized ectasia of the posterior sclera, which is the primary risk factor for various eye diseases and significantly impacts patients' quality of life. Therefore, it is essential to explore effective prevention strategies and programs for individuals with myopia. Collagen serves as the principal molecule in the extracellular matrix (ECM) of scleral tissue, consisting of irregular collagen fibrils. Collagen plays a crucial role in myopia progression and control. During the development of myopia, the sclera undergoes a thinning process which is primarily influenced by collagen expression decreased and remodeled, thus leading to a decrease in its biomechanical properties. Improving collagen expression and promoting collagen crosslinking can slow down the progression of myopia. In light of the above, improving collagen expression or enhancing the mechanical properties of collagen fibers via medication or surgery represents a promising approach to control myopia.

Age-related alterations in vortex veins on indocyanine green angiography

To determine age-related alterations in vortex veins in healthy subjects. A total of 228 healthy subjects (aged 4 to 86 years) were recruited and divided into four groups (G1, <21 years; G2, 21-40 years; G3, 41-60 years; and G4, 61-86 years). The clinical characteristics of the participants were recorded, and parameters including the number of vortex vein roots (NVVR), the central vortex vein diameter (CVVD), the mean root area of the vortex vein (MRAVV), and the weighted mean of the thickest branch diameter (WMTBD) were obtained by marking the vortex veins on indocyanine green angiography (ICGA). The NVVR in the age group over 60 years old was significantly lower than that in other age groups (P < 0.05). The CVVD, MRAVV, and WMTBD of all age groups increased with increasing age (P < 0.05). The NVVR was unevenly distributed among the quadrants (P < 0.001). The proportions of type four vortex veins (complete systems including ampulla) and anastomotic branches of the vortex veins were significantly increased in elderly participants over 50 years of age (P < 0.05). Subfoveal choroidal thickness was significantly correlated with age, NVVR, CVVD and MRAVV (P < 0.05). This is the first study to reveal age-related alterations in vortex veins on ICGA in a healthy population. Aging may lead to partial vortex occlusion and residual vortex dilation. As age increases, anastomotic branches increasingly appear between the originally independent vortex veins. Translational relevance: Aging may lead to partial vortex occlusion and residual vortex dilation.

Surgical Outcomes, Ocular Safety and Tolerability of Bio-Interventional Cyclodialysis with Allograft Scleral Reinforcement: Clinical Experience of More than 240 Cases

Background: To report the surgical safety of reinforced bio-interventional cyclodialysis with scleral allograft reinforcement. Methods: This was a consecutive case series of 243 eyes with open-angle glaucoma who underwent a bio-scaffolded cyclodialysis (BSC) procedure for uveoscleral outflow enhancement using allogeneic bio-spacers to maintain patency of the internal filtration conduit. Results: 79% of the eyes underwent concomitant phacoemulsification cataract surgery prior to BSC intervention, while the remaining eyes underwent stand-alone BSC surgery. All patients had a postoperative surgical safety period of at least 30 days. There were no sight-threatening or serious ocular adverse events. There was one case of prolonged iritis beyond 30 days, which resolved with topical treatment. Two cases (0.8%) of intraoperative and five (2%) of postoperative non-sight-threatening hyphema were without clinical sequelae, which resolved with conservative management. There were 11 cases of IOP elevation and one case of numeric hypotony without maculopathy, which resolved within the study period. The rate of secondary surgical intervention for IOP control was low, and overall, IOP for the cohort improved in the postoperative period, with 78.6% of eyes achieving IOP ≤ 18 mmHg without an increase in medications. Conclusions: Allogeneic biotissue for cyclodialysis intervention demonstrates a biocompatible ocular profile as an implantable material for internal scleral reinforcement during uveoscleral outflow enhancement surgery.