The impact of ocular blood flow in glaucoma

Changes in vascular resistance with intraocular pressure and damage severity in experimental glaucoma

There is evidence of changes in retinal hemodynamics in both experimental glaucoma and human disease. A major potential confound is that intraocular pressure (IOP) may also be directly affecting vascular resistance and/or the vasodilatory capacity of vessels in the optic nerve head and retina. This is particularly problematic in experimental glaucoma, where chronic IOP elevation is maintained, without the IOP-reducing medications typically used by patients involved in human studies. However, those animal studies remain invaluable, due to the possibility of extensive baseline testing in the knowledge that no glaucomatous loss has commenced, and due to the degree of control that is possible over parameters such as medication regimens. In this study, we aim to assess the impact of chronic IOP elevation on vascular resistance parameters, and separate it from the impact of glaucomatous damage severity. Longitudinal measurements were made using laser speckle flowgraphy before and after unilateral IOP elevation in 31 non-human primates. The pulsatile waveform was extracted and used to calculate the pulsatility index (maximum minus minimum, as a proportion of the mean) and resistivity index (maximum flow minus minimum flow, as a proportion of the maximum), in both the major vessels and the other tissue within the optic nerve head, for an average of 18 time points per animal. The vascular resistance indices increased with IOP at both locations, both in the full dataset, and in the subset of data points restricted to the visit at which IOP first exceeded 30 mmHg until the resistance index reached its maximum for that eye (all p < 0.001). After adjusting for the influence of IOP using coefficients from linear mixed effects models, the resistance indices exhibited non-monotonic relations with damage severity, first increasing from baseline, but then decreasing back to or beyond the normal range in eyes with more severe damage. Further studies are needed to accurately characterize the location and timing of these changes during the course of glaucomatous damage, which would help identify the pathophysiologic processes that are underway at different stages of the disease.

Eye yoga for glaucoma: recovery of vascular dysregulation and visual field function-a randomized controlled trial

Purpose

Because stress can aggravate vascular dysregulation (VD) in primary open-angle glaucoma (POAG), stress reduction by eye yoga (EY) was studied if this predictive, preventive, and personalized medical (3PM) approach could help normalize intraocular pressure (IOP), retinal vessel dynamics, and visual fields (VF).

Patients and methods

POAG patients were randomized to an EY (n = 15) or control group (n = 12). EY was practiced daily for 1 h for 1 month at home using an iPod-audio guide while control patients read relaxing books daily.

Results

After intervention, EY patients, but not controls, showed a 6.4% IOP reduction (p = 0.027) and had significant VF improvements (p < 0.001). After EY, pattern deviation recovered in VF regions where small microvessels showed reduced vasoconstriction (artery: p = 0.012; vein: p = 0.042) and improved mean artery diameter recovered significantly (p = 0.015). When pooling data of both groups, recovered VF regions, but not non-recovered fields, showed significantly larger arterial diameter gains (2.4 [- 0.3-5.3] MU) with no adverse events.

Conclusions and 3PM recommendations

Because EY reduces vasoconstriction and improves VF function in POAG, we propose the "eye ball retraction theory," whereby ocular muscle tension is induced by mental stress which is a contributing mechanism, or even the key mechanism, of POAG. Reducing stress by relaxation is therefore a remedy for it improves blood flow as the fundamental mechanism of vision recovery and restoration. VD reduction is therefore a valuable therapeutic target for glaucoma care and eye yoga home exercises are a safe and effective complementary 3PM method of POAG care.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-024-00389-x.

Optical Microangiography and Progressive Retinal Nerve Fiber Layer Loss in Primary Angle Closure Glaucoma

PRCIS

Younger patient age (coefficient: 0.10, P =0.04) and greater peak IOP during follow-up (coefficient: -0.14, P =0.03), but not baseline optical microangiography parameters, were significantly associated with a faster rate of RNFL loss in mild-moderate PACG.

PURPOSE

To evaluate the association between optical microangiography (OMAG) measurements and progressive retinal nerve fiber layer (RNFL) loss in primary angle closure glaucoma (PACG).

METHODS

In a prospective study, 45 eyes of 30 PACG patients (86 hemifields) with mild to moderate functional damage were longitudinally studied for at least 2 years and with a minimum of 3 optical coherence tomography (OCT) examinations. OMAG imaging was performed at the baseline visit. Effect of clinical parameters (age, sex, presence of systemic diseases, central corneal thickness, mean, peak, and fluctuation of intraocular pressure during follow-up), baseline hemifield mean deviation (MD) and baseline OMAG [quadrant peripapillary and macular perfusion density(PD)] on the rate of RNFL change was evaluated using linear mixed models.

RESULTS

The average (±SD) hemifield MD, RNFL thickness, peripapillary PD and macular PD of the analyzed quadrants at baseline were -6.0±3.4 dB, 89±21 µm, 40.1±3.5%, and 29.6±10.3%, respectively. The rate of quadrant RNFL change was -2.5±1.7 µm/year. Multivariate mixed models showed that younger patient age (coefficient: 0.10, P =0.04) and higher peak IOP during follow-up (coefficient: -0.14, P =0.03) were significantly associated with a faster rate of RNFL loss.

CONCLUSIONS

Younger patient age and greater peak IOP during follow-up were significantly associated with a faster rate of RNFL loss in PACG patients with mild to moderate severity of functional damage. None of the OMAG parameters at baseline were associated with RNFL thinning suggesting a limited role of OCTA imaging in predicting structural progression in mild-moderate PACG.

Microglial regulation of the retinal vasculature in health and during the pathology associated with diabetes

The high metabolic demand of retinal neurons requires a precisely regulated vascular system that can deliver rapid changes in blood flow in response to neural need. In the retina, this is achieved via the action of a coordinated group of cells that form the neurovascular unit. While cells such as pericytes, Müller cells, and astrocytes have long been linked to neurovascular coupling, more recently the resident microglial population have also been implicated. In the healthy retina, microglia make extensive contact with blood vessels, as well as neuronal synapses, and are important in vascular patterning during development. Work in the brain and retina has recently indicated that microglia can directly regulate the local vasculature. In the retina, the fractalkine-Cx3cr1 signalling axis has been shown to induce local capillary constriction within the superficial vascular plexus via a mechanism involving components of the renin-angiotensin system. Furthermore, aberrant microglial induced vasoconstriction may be at the centre of early vascular reactivity changes observed in those with diabetes. This review summarizes the recent emerging evidence that microglia play multiple roles in retinal homeostasis especially in regulating the vasculature. We highlight what is known about the role of microglia under normal circumstances, and then build on this to discuss how microglia contribute to early vascular compromise during diabetes. Further understanding of the mechanisms of microglial-vascular regulation may allow alternate treatment strategies to be devised to reduce vascular pathology in diseases such as diabetic retinopathy.

Baseline choroidal microvasculature dropout as a predictor of rapid global structural loss in open-angle glaucoma

This study included 102 open-angle glaucoma (OAG) eyes with or without a localized choroidal microvasculature dropout (CMvD) at the inferior hemiretina, matched for age (≤ 10 years), axial length (≤ 1 mm), and visual field severity (≤ 1dB), and with a minimum 2-year follow-up. Serial thickness [circumpapillary retinal nerve fiber layer (cpRNFLT) and macular ganglion cell-inner plexiform layer thickness (mGCIPLT)], and vessel density (VD) [circumpapillary (cpVD) and macular VD (mVD)] parameters were obtained. The rate of change in each parameter at both the superior (CMvD-unaffected) and inferior (CMvD-affected) hemiretina were compared between matched eyes with (CMvD+) and without CMvD (CMvD-). Clinical factors associated with the rate of change in each parameter both globally and at the CMvD-unaffected hemiretina were also evaluated. CMvD + eyes showed significantly faster rates of VD and thickness loss at both the CMvD-affected and -unaffected hemiretina. In addition, CMvD was significantly associated with rapid loss of both VD and thickness parameters globally and at the CMvD-unaffected superior hemiretina. In conclusion, OAG eyes with CMvD show significantly faster rates of VD and thickness loss at both the CMvD-affected and unaffected hemiretina. A localized CMvD is an independent predictor of globally rapid structural loss in OAG eyes.

Evaluating the association between autoimmune disease and normal tension glaucoma: a retrospective case-control study

BACKGROUND

Limited population-based data as well as proposed mechanisms of retinal ganglion cell (RGC) loss suggest autoimmune disease may be a risk factor for glaucoma, the leading cause of irreversible blindness worldwide. Though intraocular pressure (IOP) is the leading risk factor for glaucoma onset and progression, a subset of glaucoma referred to as normal tension glaucoma (NTG) may be more likely to be associated with IOP-independent mechanisms of RGC injury including those of an inflammatory or immune nature.

METHODS

This retrospective case-control study enrolled 277 patients with NTG and the same number of age- and sex-matched controls to determine whether autoimmune disease diagnosis, treatment thereof, or relevant laboratory markers are associated with NTG.

RESULTS

There was no significant difference between the two groups in frequency of autoimmune disease overall, autoimmune disease catagorized by mechanism or organ involvement, or individual autoimmune disease including psoriasis (6% vs. 5%), rheumatoid arthritis (5% vs. 4%), inflammatory bowel disease (2% vs. 3%), Sjögren's syndrome (1% vs. 1%), sarcoidosis (1% vs. 1%), autoimmune thyroiditis (1% vs. 0%), type 1 diabetes (1% vs. 0%), or systemic lupus erythematosus (1% vs. 0%). There was also no significant difference in laboratory values or treatment of identified autoimmune conditions.

CONCLUSIONS

Our study found no significant association between autoimmune disease and NTG, suggesting that other factors may play a more significant role in the pathogenesis of NTG.

Feasibility of a method for measurement of retinal pulse-propagated wave velocity in humans

Blood flow regulation has been shown to be compromised in common ocular diseases, such as diabetic retinopathy and glaucoma. The capacity of the retinal vessels to regulate blood flow can potentially serve as an oculomics biomarker for evaluating ocular and systemic diseases. Pulse-propagated intravascular pressure waves cause deformations of the vessel walls, thus offering a means to interrogate vascular compliance. The purpose of the current study is to report a method for measuring retinal pulse-propagated wave velocity (rPWV) based on spectral analysis of pulsatile intensity waveforms in human circumpapillary retinal vasculature. Arterial and venous rPWV values, as well as inter-subject variabilities of rPWV in non-diabetic and diabetic subjects, are reported. Preliminary results demonstrated the feasibility of this method for measuring rPWV and its potential for assessment of vascular plasticity in response to blood flow changes due to ocular and systemic diseases.

Applications of Machine Learning-Driven Molecular Models for Advancing Ophthalmic Precision Medicine

Ophthalmic diseases such as glaucoma, age-related macular degeneration (ARMD), and optic neuritis involve complex molecular and cellular disruptions that challenge current diagnostic and therapeutic approaches. Advanced artificial intelligence (AI) and machine learning (ML) models offer a novel lens to analyze these diseases by integrating diverse datasets, identifying patterns, and enabling precision medicine strategies. Over the past decade, applications of AI in ophthalmology have expanded from imaging-based diagnostics to molecular-level modeling, bridging critical gaps in understanding disease mechanisms. This paper systematically reviews the application of AI-driven methods, including reinforcement learning (RL), graph neural networks (GNNs), Bayesian inference, and generative adversarial networks (GANs), in the context of these ophthalmic conditions. RL models simulate transcription factor dynamics in hypoxic or inflammatory environments, offering insights into disrupted molecular pathways. GNNs map intricate molecular networks within affected tissues, identifying key inflammatory or degenerative drivers. Bayesian inference provides probabilistic models for predicting disease progression and response to therapies, while GANs generate synthetic datasets to explore therapeutic interventions. By contextualizing these AI tools within the broader framework of ophthalmic disease management, this review highlights their potential to transform diagnostic precision and therapeutic outcomes. Ultimately, this work underscores the need for continued interdisciplinary collaboration to harness AI's potential in advancing the field of ophthalmology and improving patient care.

[Techniques for imaging optic disc vasculature in glaucomatous optic neuropathy: A review of the literature]

The anatomy and vasculature of the optic nerve head are complex and subject to numerous variations. The main risk factor for glaucomatous optic neuropathy is elevated intraocular pressure, but many other factors have been identified. A vascular component seems to play an important role in the pathogenesis and/or progression of glaucomatous optic neuropathy, either under the influence of ocular hypertension or as an independent risk factor, particularly as in normal tension glaucoma (NTG). Reduced ocular blood flow has been identified as a risk factor for glaucoma. Numerous instruments have therefore been developed to explore the vasculature of the optic nerve head and to try to better understand the changes in blood flow in the optic nerve in glaucomatous optic neuropathy. In this review, we provide an update on the various means of imaging the vasculature of the optic nerve head, from angiography to the most modern techniques with angiographic OCT and laser Doppler holography. Using the results found in glaucomatous optic neuropathies, we will explore the close link between reduced ocular blood flow and the development or progression of glaucoma. A better understanding of this pathophysiology opens the door to improved management of our glaucoma patients.

Comparing structural and vascular parameters between advanced pseudoexfoliation glaucoma and primary open angle glaucoma using optical coherence tomography angiography

BACKGROUND

To compare structural and vascular parameters between advanced pseudoexfoliation glaucoma (PXG) and primary open-angle glaucoma (POAG).

METHODS

One hundred and six eyes of 81 patients were enrolled in this cross-sectional study. All patients underwent complete ophthalmic examination and measurement of the thickness of the peripapillary retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC). The vessel densities (VD) in the peripapillary and macular area were also determined using optical coherence tomography angiography (OCTA). A linear mixed model was used for the comparison of the structural and vascular parameters between groups with adjustment for type of glaucoma, age, sex, intraocular pressure (IOP), and mean deviation (MD) of the visual field C24-2.

RESULTS

The patients in the PXG group were significantly older (68.06 ± 10.6 vs. 61.24 ± 15.23, p = 0.01) and had worse MD in the visual field C24-2 (-24.83 ± 6.18 vs. -22.37 ± 5.94, p = 0.04). Sex and IOP were comparable between groups (p > 0.05). Perippaillry RNFL and GCC thickness were not different between groups (p > 0.05). The PXG eyes showed lower VD in the average peripapillary area (32.67 ± 7.78 vs. 37.75 ± 8.87, p = 0.027) and nasal (37.45 ± 9.74 vs. 42.15 ± 7.36, p = 0.026) and inferior (38.09 ± 8.27 vs. 42.71 ± 9.13, p = 0.041) quadrants of parafovea.

CONCLUSION

The advanced PXG and POAG eyes have comparable structural defects in the peripapillary and inner macula while the PXG eyes may have more vascular deterioration, especially in the macula.

Structural and vascular assessment of the optic nerve head and macula in chronic Chagas disease

Chagas disease (CD), a parasitic infection, may have ocular repercussions in its cardiologic form, since a history of heart disease of other etiologies already has been established as a risk factor for neuropathies and maculopathies. The aim of the present study was to investigate preclinical structural and vascular optic nerve head (ONH) and macular parameters in patients with chronic CD. Nineteen patients with CD and 19 healthy subjects were evaluated with optical coherence tomography, optical coherence tomography angiography, and Laguna ONhE® software. The main outcome measures were the glaucoma discriminant factor, average peripapillary retinal nerve fiber layer thickness, macular ganglion cell complex thickness, peripapillary vascular density (VD), foveal and parafoveal thickness, foveal avascular zone area, and total foveal and parafoveal VD from the superficial and deep capillary plexus that were compared between the two groups. No significant differences were observed among the studied variables. Although our findings suggested that the cardiovascular dysfunction resulting from chronic CD does not seem to cause significant structural or vascular preclinical changes to the ONH and the macula, the results herein benefit this patient population and may provide important preliminary information about the ocular impairment caused by the condition and its possible systemic complications.

Protective effect of resveratrol on retinal damage in glaucoma: a systematic review and meta-analysis of preclinical studies

Introduction

Resveratrol, a polyphenolic compound commonly found in natural plants and fruits, exhibits potential in preventing optic nerve damage in glaucoma, as indicated by several animal studies. However, there is presently a dearth of relevant evidence available for comprehensive summarization.

Methods

In this study, we conducted an extensive search across 7 electronic databases, encompassing all pertinent animal studies for a systematic review and meta-analysis. Methodological quality was evaluated using SYRCLE's bias risk tool, with statistical analysis performed using Stata 17.0. The primary outcome measures included the survival of retinal ganglion cells and retinal thickness.

Results

The comprehensive analysis of the 30 included studies revealed that resveratrol can enhance the expression of Sirtuin 1(SIRT1) protein in retinal tissue (SMD: 3.00, 95% CI: 2.46, 3.53, P = 0.095), boost the survival rate of retinal ganglion cells (SMD: 4.33, 95% CI: 3.28, 5.38, P < 0.05), decelerate the thinning of retinal thickness (SMD: 4.26, 95% CI: 2.77, 5.75, P < 0.05), and enhance visual function. Its potential mechanism of action may involve the suppression of pro-inflammatory cytokine levels and cell apoptosis.

Discussion

Resveratrol emerges as a promising agent for mitigating glaucoma-related retinal damage. However, given that the animal research models utilized in the study may not fully reflect the intricate scenarios of multiple coexisting diseases in clinical settings, and the administration methods in animal models may differ from those in clinical practice, future studies should aim to provide higher levels of evidence to facilitate the clinical translation of these findings.

Systematic Review Registration

identifier [CRD42024535673].

A meta-analysis of the association between high-sensitivity c-reactive protein level and glaucoma

OBJECTIVE

Glaucoma is the second-leading cause of blindness in the US for people over the age of 40; the most common form is primary open-angle glaucoma (POAG). It has been suggested that inflammatory markers have a role in the development and the progression of glaucoma (GL). High-sensitivity C reactive protein (HsCRP) is an inflammatory marker that has been linked to cardiovascular disease and a possible link to GL. Although a number of studies have found a link between CRP and GL; POAG, normal tension glaucoma (NTG), exfoliation glaucoma (XFG), Exfoliation syndrome (XFS), other research has shown the opposite.

PURPOSE

This systematic review is to determine the association between HsCRP and GL.

METHODOLOGY

A literature search was conducted using the MEDLINE database. We identified thirty-six peer-reviewed studies.

RESULTS

Five retrospective studies were included and summed up to 164305 study participants, 161759 POAG patients, and 2546 controls. The pooled result of all studies revealed that HsCRP (SMD: 0.44 mg/dl; [95% confidence interval -0.10 to 0.99]; P = 0.11, I2 89%) concentration was not significantly higher in POAG patients compared to the healthy controls. The SMD for NTG, XFG and XFS; 0.64 mg/dl; 0.03 mg/dl, 0.03 mg/dl respectively. The pooled result revealed that HsCRP concentration was not significantly higher in POAG, NTG, XFG, and XFS. No publication bias was found using the funnel plot.

CONCLUSION

The meta-analysis concluded that there is no correlation between the elevated plasma levels of HsCRP and GL. Future studies should be conducted.

Long-Term Blood Pressure Variability and Visual Field Progression in Glaucoma

Importance

Long-term variability of blood pressure may be associated with visual field (VF) progression in patients with glaucoma.

Objectives

To investigate the association between blood pressure parameters and VF progression over time in patients with glaucoma.

Design, Setting, and Participants

This retrospective cohort study of longitudinal data included patients with suspected or confirmed glaucoma who were selected from the Diagnostic Innovations in Glaucoma Study and the African Descent and Glaucoma Evaluation Study. Patients underwent blood pressure and VF testing from November 2000 to December 2022, and data were analyzed in October 2023.

Exposure

Suspected or confirmed glaucoma.

Main Outcomes and Measures

Mean and SD values of blood pressure variables were calculated for systolic and diastolic arterial pressures. These parameters were incorporated into multivariable mixed-effect models to investigate the association between blood pressure parameters and mean intraocular pressure with rates of VF mean deviation loss. Interaction terms between blood pressure parameters and mean intraocular pressure were also included in the models.

Results

A total of 1674 eyes from 985 patients were assessed (mean [SD] age, 61.2 [0.4] years; 563 female [57.2%]). The mean rate of VF mean deviation change was -0.13 (95% CI, -0.16 to -0.10) dB/y over a mean follow-up of 8.0 (95% CI, 7.7-8.2) years. The interaction terms of higher mean blood pressure and higher SD of blood pressure were associated with faster annual mean deviation changes for both mean arterial pressure (0.02 [95% CI, 0.01-0.04] dB/y per 1-mm Hg higher; P = .001) and diastolic arterial pressure (0.02 [95% CI, 0.01-0.03] dB/y per 1-mm Hg higher; P < .001). The interaction term of higher SD of blood pressure and higher mean intraocular pressure was associated with faster annual mean deviation changes for both mean arterial pressure (0.01 [95% CI, 0.00-0.02] μm per 1-mm Hg higher; P = .003) and diastolic arterial pressure (0.01 [95% CI, 0.00-0.01] μm per 1-mm Hg higher; P = .001).

Conclusions and Relevance

In this cohort study, higher mean blood pressure and higher SD of blood pressure were associated with faster VF progression. These findings suggest that long-term variability of blood pressure may be a modifier of the association between intraocular pressure and VF progression in glaucoma.

Neuroprotective Effect of the Combination of Citicoline and CoQ10 in a Mouse Model of Ocular Hypertension

Glaucoma is a neurodegenerative disease characterized by the loss of retinal ganglion cells (RGCs), with intraocular pressure (IOP) being its primary risk factor. Despite controlling IOP, the neurodegenerative process often continues. Therefore, substances with neuroprotective, antioxidant, and anti-inflammatory properties could protect against RGC death. This study investigated the neuroprotective effects on RGCs and visual pathway neurons of a compound consisting of citicoline and coenzyme Q10 (CoQ10) in a mouse model of unilateral, laser-induced ocular hypertension (OHT). Four groups of mice were used: vehicle group (n = 6), citicoline + CoQ10 group (n = 6), laser-vehicle group (n = 6), and laser-citicoline + CoQ10 group (n = 6). The citicoline + CoQ10 was administered orally once a day starting 15 days before laser treatment, continuing until sacrifice (7 days post-laser). Retinas, the dorsolateral geniculate nucleus (dLGN), the superior colliculus (SC), and the visual cortex (V1) were analyzed. The citicoline + CoQ10 compound used in the laser-citicoline + CoQ10 group demonstrated (1) an ocular hypotensive effect only at 24 h post-laser; (2) prevention of Brn3a+ RGC death in OHT eyes; and (3) no changes in NeuN+ neurons in the dLGN. This study demonstrates that the oral administration of the citicoline + CoQ10 combination may exert a neuroprotective effect against RGC death in an established rodent model of OHT.

Accelerated Epigenetic Aging is Associated with Faster Glaucoma Progression: A DNA Methylation Study

PURPOSE

To investigate the association between epigenetic age acceleration and glaucoma progression.

DESIGN

Retrospective cohort study.

PARTICIPANTS

100 primary open-angle glaucoma (POAG) patients with fast progression and 100 POAG patients with slow progression.

METHODS

Subjects were classified as fast or slow progressors based on rates of change in standard automated perimetry (SAP) mean deviation (MD) and retinal nerve fiber layer (RNFL) thickness. Epigenetic age was calculated using the Horvath, Hannum, PhenoAge, and GrimAge clocks from DNA methylation profiles obtained from blood samples. Age acceleration (AgeAccel) was defined as the residual from a linear regression of epigenetic age on chronologic age, with positive values suggesting faster biological aging. Multivariable logistic regression models estimated the association between AgeAccel and likelihood of fast progression, adjusting for confounders.

MAIN OUTCOME MEASURES

Difference in epigenetic age acceleration between fast and slow glaucoma progressors.

RESULTS

The mean rate of SAP MD change in the fastest progressing eye was -1.06 dB/year (95% CI: -1.28 to -0.85) for fast progressors compared to -0.10 dB/year (95% CI: -0.16 to -0.04) for slow progressors (P<0.001). For RNFL thickness, corresponding values were -1.60 μm/year (95% CI: -1.97 to -1.23) and -0.76 μm/year (95% CI: -1.04 to -0.48), respectively (P<0.001). Fast progressors demonstrated significantly greater age acceleration compared to slow progressors for the Horvath clock (mean difference = 2.93 years, 95% CI: 1.48 to 4.39, P<0.001) and Hannum clock (mean difference = 1.24 years, 95% CI: 0.03 to 2.46, P=0.045). In multivariable models, each year of Horvath AgeAccel was associated with 15% higher odds of fast progression (OR 1.15, 95% CI 1.07-1.23, P<0.001), after adjusting for sex, race, intraocular pressure, central corneal thickness, baseline disease severity, smoking status and follow-up time. Hannum and GrimAge clocks also showed significant associations with fast progression. The association between AgeAccel and fast progression was stronger in subjects with relatively low IOP during follow-up.

CONCLUSION

Accelerated epigenetic aging was associated with faster glaucoma progression. These findings suggest that faster biological age, as reflected in DNA methylation, may increase optic nerve susceptibility to damage, highlighting epigenetic age as a potential prognostic biomarker.

Potential Causal Association Between Atrial Fibrillation/Flutter and Primary Open-Angle Glaucoma: A Two-Sample Mendelian Randomisation Study

Background: A few studies have reported controversial relationships between atrial fibrillation/flutter (AF/L) and primary open-angle glaucoma (POAG). This study aimed to investigate the potential causal relationship between AF/L and POAG. Methods: Single-nucleotide polymorphisms associated with exposure to AF/L were selected as instrumental variables with significance (p < 5.0 × 10-8) from a genome-wide association study (GWAS) by FinnGen. The GWAS summary of POAG from the UK Biobank was used as the outcome dataset. A two-sample Mendelian randomisation (MR) study was performed to assess the causal effects of AF/L on POAG. In addition, potential confounders, including hypertension, autoimmune hyperthyroidism, sleep apnoea, and alcohol use disorder, were assessed using multivariable MR analysis. Results: There was a significant causal association of AF/L with POAG (odds ratio [OR] = 1.26, 95% confidence interval [CI] = 1.07-1.48, p = 0.005 using inverse-variance weighting [IVW]). Multivariable MR analysis confirmed a causal association of AF/L with POAG (OR = 1.24, 95% CI = 1.02-1.51, p = 0.034 using IVW), but hypertension, hyperthyroidism, sleep apnoea and alcohol use disorder did not show significant causal associations with POAG (all p > 0.05). Conclusions: This established causal relationship between AF/L and POAG supports the need for further investigation into the role of AF/L as a possible risk factor for POAG. Further research is required to confirm these findings.

Increased risk of open angle glaucoma in patients with moyamoya disease from a nationwide population-based cohort in Korea

This nationwide population-based retrospective cohort study aims to investigate the association between Moyamoya disease (MMD) and open-angle glaucoma (OAG). In this study using the Korean National Health Insurance Service database, a total of 36,432 patients having diagnostic code with MMD between 2002 and 2022, and their age-, sex-matched non-MMD controls (n = 346,769) were included. We used a Cox proportional hazard model to determine the association between MMD and subsequent OAG after excluding cases with preexisting diagnosis of MMD for the initial 2-year. Kaplan-Meier survival analyses with log-rank test were performed to compare the incidence probability of OAG based on the MMD diagnosis. Cox regression analysis showed that the diagnosis of MMD was associated with increased risk of subsequent diagnosis of OAG (adjusted HR, 1.26; 95% CI, 1.14-1.38; P < 0.001). The cumulative incidence probability of OAG was 3.7% in MMD group and 2.9% in control group at the end of the study period, and was significantly higher among MMD patients than controls consistently during the study period (P < 0.001).In conclusion, the nationwide longitudinal data of Korean population revealed a significant association between MMD and OAG. Presence of MMD may increase the risk of developing OAG.

Study of the impact of the vascular systemic risk factors on peripapillary vascular density by optical coherence tomography angiography

BACKGROUND

The focus of therapeutic tools in glaucoma has been mainly to control of intraocular pressure. Recently there has been a growing interest in investigating the relationship of vascular risk factors in the development of glaucoma. The aim of this study was to assess the association between systemic arterial hypertension, diabetes mellitus and hypercholesterolemia, and peripapillary vascularization measured by Optical Coherence Tomography Angiography (OCTA) in glaucoma and healthy subjects.

METHODS

In this unicenter, observational, cross-sectional study, 212 subjects, 118 glaucoma patients and 94 controls were consecutively recruited. Of these, 86 participants were excluded due to poor OCTA image quality. Therefore, 146 subjects were included in the final analysis, 74 glaucoma patients and 72 controls. Using a linear regression model, with 95% confidence and 80% statistical power, the effect of vascular risk factors on OCTA parameters in the 146 subjects included in the final analysis was studied.

RESULTS

No significant impact of vascular risk factors on OCTA measurements was found. Diabetic patients tended to show a lower peripapillary perfusion vascular density than subjects without diabetes (β 0.016, 95%CI 0.003;0.030, p 0.016). Similarly, hypercholesterolemia patients appeared to show less peripapillary flow index than non-hypercholesterolaemic patients (β 0.029, 95%CI 0.013;0.046, p 0.001). Glaucoma patients had 0.02% lower peripapillary perfusion vascular density (β 0.020, 95% CI 0.011;0.029, p < 0.001), 0.04% lower peripapillary flow index (β 0.036, 95%CI 0.022;0.051, p < 0.001) and 9.62% thinner retinal nerve fibre layer (β 9.619, 95%CI 5.495;13.744, p < 0.001).

CONCLUSIONS

In conclusion glaucoma has greater effect on peripapillary vascular density parameters than any of the vascular risk factors analyzed.

KEY MESSAGES

What is known: • Vascular disfunction plays an important role in the development of glaucoma. • Optical coherence tomography angiography makes it possible to assess the retinal microvasculature and the role that its alterations could have in the development of glaucoma.

WHAT IS NEW

• Decrease of the peripapillary microcirculation seems to be more related to the increase in intraocular pressure and the glaucoma itself than to the presence of cardiovascular risk factors. • The effect of having diabetes, systemic arterial hypertension or hypercholesterolaemia on vascular parameters or nerve fibre layer thickness was low. • There was also no relevant impact of the systemic medication used for these diseases on the peripapillary vascular parameters studied or on nerve fibre layer thickness.

Systemic Arterial Stiffness and Choroidal Microvascular Insufficiency on the Structural Progression of Normal Tension Glaucoma

PURPOSE

To identify the role of systemic arterial stiffness and choroidal microvascular insufficiency on structural progression of normal-tension glaucoma (NTG).

DESIGN

Retrospective cohort study.

METHODS

A total of 107 early NTG eyes of 88 patients, who underwent pulse wave velocity (PWV) measurements and optical coherence tomography (OCT) angiography (OCT-A) at baseline, were categorized depending on the presence of peripapillary choroidal microvasculature dropout (MvD) and PWV. Differences in glaucomatous progression were analyzed. Structural progression rates were determined using the trend-based analysis of Cirrus OCT.

RESULTS

Thirty-two eyes displayed choroidal MvD (62.7 [95% CI 58.4-67.0] years old, 53.6% males), and 70 eyes did not show any MvD (59.9 (95% CI 57.1-62.6) years old, 53.3% males) at baseline. Patients were followed for 48.4 (95% CI 40.0-56.8) months. When they were further divided based on PWV (high PWV ≥ 1400 cm/sec), those with choroidal MvD and high PWV showed significantly faster thinning in macular ganglion cell-inner plexiform layer (GCIPL; P = .023). In comparison to those with low PWV and no MvD, eyes with high PWV and MvD in the peripapillary area were likely to show fast structural progression (≤-1.2 µm/year) in the macular GCIPL by odds of 6.019 (95% CI 1.619-38.531, P = .025).

CONCLUSIONS

In NTG eyes, GCIPL thinning was faster when choroidal MvD and high systemic arterial stiffness were present. The simultaneous presence of regional and systemic vascular insufficiency may be associated with rapid glaucoma structural progression in eyes with low baseline intraocular pressure.

Earliest location of glaucomatous retinal nerve fibre layer damage is determined by intact baseline RNFL thickness profile

BACKGROUND/AIMS

To identify whether an intact retinal nerve fibre layer (RNFL) thickness profile could determine the location of the earliest RNFL defect in glaucoma.

METHODS

Retrospective longitudinal cohort study of patients with initial unilateral glaucoma who eventually developed new glaucoma in the fellow eye. Guided progression analysis (GPA) of serial optical coherence tomography (OCT) examinations was used to identify the angular locations of the earliest RNFL defect, peak and temporal edge of the baseline RNFL profile and major vessels based on the peripapillary OCT scan circle.

RESULTS

We identified 112 new RNFL defects in 109 fellow eyes of 109 consecutive patients. The locations of new defects were superotemporal (22 eyes), inferotemporal (87 eyes) and papillomacular bundle (3 eyes), respectively. Overall, the midpoint location of the earliest RNFL defect strongly coincided with the RNFL peak (p<0.001). Specifically, the location was mildly (4.3±12.0°) temporal to, rather than at the peak thickness, particularly in eyes with a focal thinning pattern of arcuate bundles (7.8±10.8°). The close topographical relationship was consistent regardless of the interindividual variability in the RNFL profile and vessels, as well as hemispheric locations, and after adjusting for potential factors including age, refractive error, baseline intraocular pressure, tilt ratio, tilt axis and glaucoma diagnosis.

CONCLUSION

The location of the earliest RNFL defect in glaucoma showed a close relationship with the intact RNFL profile within the same eye, regardless of variations in RNFL, hemispheric location and vessel distribution. In addition, the earliest defect was located mildly temporal to, rather than at, the peak RNFL thickness. The baseline RNFL profile may have a significant role in the regional vulnerability of glaucoma.

The impact of different forms of exercise on intraocular pressure, blood flow, and the risk for primary open angle glaucoma

Primary open angle glaucoma (POAG) is a chronic disease characterized by progressive optic nerve damage and irreversible loss of vision, often diagnosed at late stages. Elevated intraocular pressure (IOP) is the major risk factor for its onset and progression while older age, myopia, genetic factors, blood pressure (BP), and reduced ocular blood flow (OBF) have also been linked to the disease. Different forms of exercise are known to have significant, but variable, effects on IOP, BP, ocular perfusion pressure (OPP), OBF and oxygen metabolism, and ultimately the risk for development and progression of POAG. While population-based studies lack agreement regarding the relationship between exercise and POAG status, data suggests that resistance training causes a short-term increase in IOP, BP, and OPP. Conversely, aerobic exercise has been shown to cause a short-term decrease in IOP and increase in BP and OPP. Research also suggests that following an exercise program over an extended period may lead to a long-term decrease in IOP, however its cessation results in a prompt return to baseline levels. Data suggests normal vascular autoregulation ensures minimal change in OBF following extended exercise unless OPP rises ∼70% above baseline. Although exercise may alter IOP, BP, and OBF, both acutely and chronically, it is currently uncertain if physical activity significantly alters risk for the onset and progression of POAG.

Rates of Choriocapillaris Microvascular Dropout and Macular Structural Changes in Glaucomatous Optic Neuropathy With and Without Myopia

PURPOSE

To evaluate the association between rates of juxtapapillary choriocapillaris microvasculature dropout (MvD) change and rates of ganglion cell inner plexiform layer (GCIPL) loss in primary open-angle glaucoma (POAG) and glaucoma suspect eyes with and without myopia.

DESIGN

Cohort study from clinical trial data.

METHODS

238 eyes from 155 POAG and glaucoma suspect patients were stratified into no-myopia (axial length (AL) ≤ 24 mm; n = 78 eyes), mild myopia (24 mm < AL ≤ 26 mm; n = 114 eyes), and high myopia (AL > 26 mm; n = 46 eyes). Eyes with a minimum of 3 visits and 1.5 years of follow-up with both optical coherence tomography angiography (OCT-A) and OCT macula scans were included. Presence, area, and angular circumference of juxtapapillary MvD were evaluated on en face choroidal images and horizontal B-scans obtained from OCT-A imaging.

RESULTS

Over the mean follow-up of 4.4 years, the mean MvD area rates of change (95% CI) were largest in high and mild myopia group (0.04 [0.03, 0.05] mm2/year in both groups), followed by the no-myopia group (0.03 [0.02, 0.04] mm2/year). The mean MvD angular circumference rates of change (95% CI) were highest in mild myopia group (8.7° [6.9°, 10.5°]/year) followed by the high myopia and no-myopia groups (8.1° [5.3°, 10.9°]/year, and 7.4° [5.3°, 9.6°]/year, respectively). While the mean global GCIPL thinning rates between eyes with MvD at baseline compared to eyes without were similar in all myopia groups, the rates of MvD area change were significantly faster in all myopia groups with baseline MvD (all p ≤ 0.004). Significant faster rates of MvD angular circumference change were found in the mild myopia group with baseline MvD (P < .001) only. In multivariable models, the rates of GCIPL thinning over time were significantly associated with rates of MvD angular circumference change and MvD area change (R2 = 0.33, P < .001 and R2 = 0.32, P = .006, respectively).

CONCLUSIONS

Rates of GCIPL thinning were associated with rates of MvD area and angular circumference change over time in myopic POAG eyes. Utilizing OCT-A to detect MvD may provide an additional tool for monitoring macular structural changes in glaucomatous eyes with myopia.

Vascular resistance indices are higher in the superior than inferior optic nerve head and retina

Retinal vascular resistance is of interest in glaucoma research, as a potential link between retinal ganglion cell loss and observed phenomena including disrupted vascular autoregulation, altered biomechanical stiffness, and impaired neurovascular coupling. It can now be assessed in vivo, using laser speckle flowgraphy. However, continued progress in the field requires better understanding of its physiology. In this study, we test the hypothesis of homogeneity of vascular resistance indices between regions of the retina: specifically, between superior and inferior hemifields. The resistivity index (maximum flow minus minimum flow, as a proportion of the maximum) and pulsatility index (maximum minus minimum, as a proportion of the mean) were measured in major vessels within the optic nerve head, in the remaining tissue within the optic nerve head, and in peripapillary branch retinal arteries, separated in each case into superior and inferior quadrants. This was performed in 378 eyes of 189 participants with suspected, early or moderate glaucoma; and in 99 eyes of 50 participants without any ocular pathology. In the glaucoma cohort, the resistivity index was on average 9% higher superiorly than inferiorly in vessels within the optic nerve head; 8% higher superiorly in remaining tissue; and 8% higher superiorly in peripapillary vessels (all p < 0.001). The pulsatility index was on average 11% higher superiorly in all three locations (all p < 0.001). Average flow was slightly higher superiorly in major vessels in the nerve head, but higher inferiorly elsewhere. In the healthy control cohort, resistivity index was higher superiorly by 10% in vessels and 8% in tissue within the optic nerve head; pulsatility index was 12% and 10% higher superiorly respectively (all p < 0.001). The fact that these differences were similar between the two cohorts suggests that they are not caused by the disease process. However, it is notable that glaucomatous loss most frequently occurs first in the superior visual field, corresponding with the inferior retina. The finding that vascular resistance indices are consistently higher in the superior retina warrants further investigation, both for its causes and consequences.

Histamine H3 receptor antagonist/nitric oxide donors as novel promising therapeutic hybrid-tools for glaucoma and retinal neuroprotection

Glaucoma is a degenerative optic neuropathy in which the degeneration of optic nerve and blindness occur. The main cause is a malfunction of ciliary processes (protrusions of the ciliary bodies) resulting in increased intraocular pressure (IOP). Ocular hypertension (OHT) causes ischemic events leading to retinal ganglion cell (RGC) depletion and blindness. Histaminergic and nitrergic systems are involved in the regulation of IOP. Therefore, we developed novel hybrid compounds that target histamine H3 receptor (H3R) with nitric oxide (NO) releasing features (ST-1989 and ST-2130). After H3R binding was proven in vitro, we investigated their effects in two OHT models in New Zealand White rabbits. Compound ST-1989 showed the highest NO elevation, together with antioxidative and anti-inflammatory features partly superior to the co-administered H3R antagonist (ciproxifan) and NO donor (molsidomine). This hybrid compound demonstrated IOP reduction in both OHT models induced by intravitreal injection of hypertonic saline and carbomer into the anterior chamber of the eye, respectively. Ocular perfusion and photoreceptor neuroprotection were evaluated in a model of ischemia/reperfusion (I/R) of the ophthalmic artery induced by repeated sub-tenon injections of endothelin-1 (ET-1), twice a week for six weeks. Compound ST-1989 counteracts retinal degeneration reducing ophthalmic artery resistance index and increasing photoreceptor responses, thus rescuing RGCs. Our results indicate that compound ST-1989 is a promising molecule with long-lasting hypotensive effects and good effectiveness in reducing inflammation, oxidative stress, and RGCs apoptosis. In conclusion, these hybrid compounds could be a novel strategy to combat glaucomatous blindness and RGC depletion for ocular diseases involving retinal damage.

Differential protein expression and metabolite profiling in glaucoma: Insights from a multi-omics analysis

Various substances within the aqueous humor (AH) can directly or indirectly impact intraocular tissues associated with intraocular pressure (IOP), a critical factor in glaucoma development. This study aims to investigate individual changes in these AH substances and the interactions among altered components through a multi-omics approach. LC/MS analysis was conducted on AH samples from patients with exfoliation syndrome (XFS, n = 5), exfoliation glaucoma (XFG, n = 4), primary open-angle glaucoma (POAG, n = 11), and cataracts (control group, n = 7). Subsequently, differentially expressed proteins and metabolites among groups, alterations in their network interactions, and their biological functions were examined. Both data-independent acquisition and data-dependent acquisition methods were employed to analyze the AH proteome and metabolome, and the results were integrated for a comprehensive analysis. In the proteomics analysis, proteins upregulated in both the XFG and POAG groups were associated with lipid metabolism, complement activation, and extracellular matrix regulation. Metabolomic analysis highlighted significant changes in amino acids related to antioxidant processes in the glaucoma groups. Notably, VTN, APOA1, C6, and L-phenylalanine exhibited significant alterations in the glaucoma groups. Integration of individual omics analyses demonstrated that substances associated with inflammation and lipid metabolism, altered in the glaucoma groups, showed robust interactions within a complex network involving PLG, APOA1, and L-phenylalanine or C3, APOD, and L-valine. These findings offer valuable insights into the molecular mechanisms governing IOP regulation and may contribute to the development of new biomarkers for managing glaucoma.

Orbital decompression improves visual function and macular blood perfusion status in patients with thyroid-related eye disease

Background

Orbital decompression surgery is a treatment option for Thyroid-associated Ophthalmopathy (TAO). However, its effects on visual function and macular perfusion status remain unclear. This study examined how orbital decompression surgery affects visual acuity and macular blood flow in TAO patients and the variation between these two factors.

Methods

This study involved cross-sectional and longitudinal analyses of 54 TAO patients, who were categorized into a normal vision group (n = 40) and an impaired vision group (n = 14) based on the presence of visual impairment before surgery (LogMAR BCVA >0.097). Among the participants, 20 underwent orbital decompression surgery (normal vision group: n = 13, impaired vision group: n = 7). BCVA and IOP were assessed at baseline in patients with TAO, and macular retinal blood perfusion indices were measured using OCTA. One month post-operatively, changes in these indices were compared between the two groups, and the correlation between visual acuity and macular perfusion indices was analyzed.

Results

The LogMar BCVA in the visual impairment group was significantly worse than that in the normal vision group (p < 0.001), while the W-MVD was significantly lower (p = 0.01). In the visual impairment group, post-operative LogMar BCVA improved significantly (p = 0.038), and W-MVD increased significantly (p = 0.008) compared to baseline. However, there were no significant changes in LogMar BCVA, S-MVD, D-MVD, or W-MVD in the normal vision group from preoperative to postoperative assessments. A strong negative correlation was found between the changes in W-MVD and changes in LogMar BCVA in the eyes of the visual impairment group treated with orbital decompression (Pearson correlation coefficient, R = -0.812, p = 0.05).

Conclusion

This study found that TAO patients with visual impairment had lower macular blood flow perfusion than those with normal vision. Endoscopic orbital decompression surgery was found to improve both the best-corrected visual acuity and macular blood flow perfusion in TAO patients with visual impairment, and the improvement in visual acuity was correlated with the improvement in macular blood flow perfusion.

GWAS-by-subtraction reveals an IOP-independent component of primary open angle glaucoma

The etiology of primary open angle glaucoma is constituted by both intraocular pressure-dependent and intraocular pressure-independent mechanisms. However, GWASs of traits affecting primary open angle glaucoma through mechanisms independent of intraocular pressure remains limited. Here, we address this gap by subtracting the genetic effects of a GWAS for intraocular pressure from a GWAS for primary open angle glaucoma to reveal the genetic contribution to primary open angle glaucoma via intraocular pressure-independent mechanisms. Seventeen independent genome-wide significant SNPs were associated with the intraocular pressure-independent component of primary open angle glaucoma. Of these, 7 are located outside known normal tension glaucoma loci, 11 are located outside known intraocular pressure loci, and 2 are novel primary open angle glaucoma loci. The intraocular pressure-independent genetic component of primary open angle glaucoma is associated with glaucoma endophenotypes, while the intraocular pressure-dependent component is associated with blood pressure and vascular permeability. A genetic risk score for the intraocular pressure-independent component of primary open angle glaucoma is associated with 26 different retinal micro-vascular features, which contrasts with the genetic risk score for the intraocular pressure-dependent component. Increased understanding of these intraocular pressure-dependent and intraocular pressure-independent components provides insights into the pathogenesis of glaucoma.

Accelerated Epigenetic Aging is Associated with Faster Glaucoma Progression: A DNA Methylation Study

Purpose

To investigate the association between epigenetic age acceleration and glaucoma progression.

Design

Retrospective cohort study.

Participants

100 primary open-angle glaucoma (POAG) patients with fast progression and 100 POAG patients with slow progression.

Methods

Subjects were classified as fast or slow progressors based on rates of change in standard automated perimetry (SAP) mean deviation (MD) and retinal nerve fiber layer (RNFL) thickness. Epigenetic age was calculated using the Horvath, Hannum, PhenoAge, and GrimAge clocks from DNA methylation profiles obtained from blood samples. Age acceleration (AgeAccel) was defined as the residual from a linear regression of epigenetic age on chronologic age, with positive values suggesting faster biological aging. Multivariable logistic regression models estimated the association between AgeAccel and likelihood of fast progression, adjusting for confounders.

Main Outcome Measures

Difference in epigenetic age acceleration between fast and slow glaucoma progressors.

Results

The mean rate of SAP MD change in the fastest progressing eye was -1.06 dB/year (95% CI: -1.28 to -0.85) for fast progressors compared to -0.10 dB/year (95% CI: -0.16 to -0.04) for slow progressors (P<0.001). For RNFL thickness, corresponding values were -1.60 μm/year (95% CI: -1.97 to -1.23) and -0.76 μm/year (95% CI: -1.04 to -0.48), respectively (P<0.001). Fast progressors demonstrated significantly greater age acceleration compared to slow progressors for the Horvath clock (mean difference = 2.93 years, 95% CI: 1.48 to 4.39, P<0.001) and Hannum clock (mean difference = 1.24 years, 95% CI: 0.03 to 2.46, P=0.045). In multivariable models, each year of Horvath AgeAccel was associated with 15% higher odds of fast progression (OR 1.15, 95% CI 1.07-1.23, P<0.001), after adjusting for sex, race, intraocular pressure, central corneal thickness, baseline disease severity, smoking status and follow-up time. Hannum and GrimAge clocks also showed significant associations with fast progression. The association between AgeAccel and fast progression was stronger in subjects with relatively low IOP during follow-up.

Conclusion

Accelerated epigenetic aging was associated with faster glaucoma progression. These findings suggest that faster biological age, as reflected in DNA methylation, may increase optic nerve susceptibility to damage, highlighting epigenetic age as a potential prognostic biomarker.

Factors Associated with Retinal Microvasculature Dropout Induced by Elevation of Intraocular Pressure in Primary Open-Angle Glaucoma

PURPOSE

To investigate the risk factors related to decrease in vessel density (VD) observed in primary open-angle glaucoma (POAG), due to acute increase in intraocular pressure (IOP) by an ophthalmodynamometer (OPD).

METHODS

This cross-sectional study involved 42 eyes of participants (22 Controls and 20 POAG patients) that underwent optical coherence tomography angiography (OCT-A) to assess VD in the peripapillary region in three examination sets: primary gaze position (1), 25-degree adduction (2) and 25-degree adduction with OPD compression (3). Individual relationships between IOP levels and changes in the superficial complex VD were evaluated after image processing and exclusion of large retinal vessels. Multivariable regression analysis was used to verify factors associated with differences in VD induced by IOP elevation.

RESULTS

A significant increase in IOP was induced by OPD compression during adduction (mean ± SD, Control: + 13.8 ± 2.8; POAG: + 13.4 ± 2.1 mmHg). Only during IOP elevation (set 3), a significant VD decrease was observed both in POAG eyes (p = 0.008) and controls (p = 0.022). Baseline IOP (p = 0.022), maximum IOP (p = 0.003), and scleral rigidity (p = 0.029) were significantly associated with VD decreases in eyes with POAG. No changes were observed in VD during adduction gaze exclusively.

CONCLUSION

Acute IOP elevation induced with OPD, but not adduction gaze, decreased peripapillary VD measured with OCT-A imaging. IOP levels and scleral rigidity significantly affected VD reduction in POAG patients. Thus, high scleral rigidity may decrease the ability of the globe to dampen the well-known effects of IOP fluctuation on glaucoma onset and progression.

KEY MESSAGES

What is known Decrease vascular density in the peripapillary retina was associated with POAG, but factors related to the vascular response to elevated IOP are unexplored. What is new OCT-A quantification shows decreases in vascular density of the superficial layers of the peripapillary retina during an acute elevation in IOP. High IOP levels and scleral rigidity significantly affected vascular density reduction in POAG patients.

Relationship Between Retinal Oxygen Saturation and the Severity of Visual Field Damage in Glaucoma

PRCIS

Increased oxygen saturation (StO 2 ) was significantly associated with the severity of visual field (VF) damage in patients with glaucoma.

OBJECTIVE

To investigate the association between retinal StO 2 percentage and the severity of VF loss in glaucoma.

METHODS

A total of 198 eyes from 131 patients with glaucoma were included in this cross-sectional study. Participants underwent imaging using ocular oximetry (Zilia) and 24-2 Swedish Interactive Threshold Algorithm standard VF (Carl Zeiss-Meditec). StO 2 (%) was measured at 2 locations of the peripapillary optic nerve head (superotemporal, and inferotemporal). Measurements were reported as the mean of at least 5 measurements in each location. Associations between the severity of VF loss, reported as mean deviation, and StO 2 (%) were calculated.

RESULTS

A total of 198 eyes of 131 patients (mean (95% CI) age, 71.1 (68.9,73.3) years, 68 females (51.9%), and 63 males (48.1%) were analyzed. In univariable analysis, higher StO 2 -0.06 (-0.12, 0.00) was associated with severity in all hemifields ( P = 0.047). Multivariate regression analysis showed that each 1% increase in StO 2 was associated with -0.06 (-0.12, -0.00) dB loss in mean deviation in all hemifields ( P = 0.043). In multivariate regression analysis in the superior hemifields, higher StO 2 -0.07 (-0.16, 0.01) tended to be associated with superior hemifield severity ( P = 0.09).

CONCLUSIONS

Retinal oximetry enabled the continuous quantitative measurement of retinal StO 2. Increased StO 2 was significantly associated with the severity of VF damage in patients with glaucoma.

Association of Smoking Patterns with Vision-Related Disability According to Glaucoma Subtypes

OBJECTIVE

The relationship between smoking and onset of glaucoma has been inconsistent. However, there is a gap in understanding whether tobacco smoking is linked to a worse visual impairment in different glaucoma subtypes. The objective of this study was to examine the association between smoking behavior and vision-related disability in people who have different glaucoma subtypes.

METHODS

A total of 283 people with primary open-angle glaucoma (POAG), primary angle closure glaucoma (PACG), normal tension glaucoma (NTG), and pseudo-exfoliative (PEX) were included in this cross-sectional study. The recruitment of study participants was organized in one of two tertiary centers for eye diseases in Belgrade, Serbia, during their regular eye checks. Information about the duration and quantity of smoking was self-reported. Vision-related impairment was quantified using a validated Glaucoma Quality of Life-15 (GQL-15) questionnaire.

RESULTS

A series of multiple linear regression models adjusted for age, gender, severity of glaucoma, lifestyle, and mobility, intraocular pressure level, visual parameters, previous and current therapy, and chronic illnesses suggested that a higher quantity of cigarettes smoked per day was associated with poorer vision-related quality of life only among people with NTG subtypes. This association was absent when smoking duration was tested in the adjusted linear regression model.

CONCLUSION

A higher number of cigarettes smoked daily was associated with poorer vision-related impairment among people who have NTG, but not other glaucoma subtypes. It is recommended that ophthalmologists and other health-care professionals work to improve their patients' understanding of harmful effects of tobacco smoke and quit smoking.

Lycium Barbarum Polysaccharide-Derived Nanoparticles Protect Visual Function by Inhibiting RGC Ferroptosis and Microglial Activation in Retinal Ischemia‒Reperfusion Mice

Retinal ischemia‒reperfusion (IR) is a major contributor to vision impairment and irreversible vision loss due to retinal ganglion cell (RGC) injury or loss. Contemporary therapeutic approaches predominantly focus on the amelioration of symptoms rather than addressing the fundamental etiological factors. Oxidative stress is a notable feature and an important mediator of IR damage. Lycium barbarum polysaccharide (LBP), the main active ingredient of Lycium barbarum, has various pharmacological effects, including antioxidation, immunoregulation, and neuroprotective effects. In this study, the ROS-consumable moiety phenylboronic acid pinacol ester (PBA) is introduced to LBP molecules, which can self-assemble into nanoparticles in aqueous solution. This nanoparticle (termed PLBP) can reduce the cellular ROS levels and enhance the antioxidant capability of RGCs by activating the NRF2 pathway, thus protecting RGCs from ferroptosis and preserving visual function in response to IR injury. PLBP also reduces neuroinflammation by inhibiting the ability of microglia to phagocytose, migrate, secrete inflammatory cytokines, and activate the NF-κB pathway. In conclusion, this approach can be used as an inspiration for the future development of neuroprotective drugs.

The retinal venous pressure at different levels of airway pressure measured with a new method

PURPOSE

This study is to investigate the increase in retinal venous pressure (RVP) induced by a stepwise increase in airway pressure (AirP) using the new IOPstim method, which is designed to artificially increase the intraocular pressure (IOP) and thus to stimulate vascular pulsation.

METHODS

Twenty-eight healthy subjects were examined in the left eye. The RVP was measured at baseline and at four different levels of AirP (10, 20, 30, and 40 mmHg) using the new IOPstim method: a half balloon of 8 mm diameter is inflated laterally to the cornea under observation of the central retinal vein. As soon as the vein pulsates at a certain AirP level, the IOP is measured with a commercially available tonometer, which then corresponds to the RVP.

RESULTS

Spontaneous venous pulsation was observed in all study participants. The mean RVP values at baseline and at the AirP levels of 10, 20, 30, and 40 mmHg were 17.6 ± 2.8 mmHg; 20.1 ± 3.0 mmHg; 22.1 ± 3.5 mmHg; 24.3 ± 3.7 mmHg, and 26.6 ± 4.2 mmHg, respectively. The mean RVP values of each AirP level were statistically significantly different from each other in pairwise comparison. In a linear mixed model, the effect of AirP on RVP was highly significant (p < 0.001). In the model, a 10-mmHg increase in AirP resulted in a linear increase in RVP of 2.2 mmHg.

CONCLUSION

An increase in AirP was accompanied by a linear increase in RVP. The influence of AirP on RVP, and thus on retinal perfusion pressure during the Valsalva maneuver, is less than was assumed based on previous studies in which contact lens dynamometry was used.

Lycium barbarum glycopeptide promotes neuroprotection in ET-1 mediated retinal ganglion cell degeneration

BACKGROUND

Vascular dysregulation is one of the major risk factors of glaucoma, and endothelin-1 (ET-1) may have a role in the pathogenesis of vascular-related glaucoma. Fruit extract from Lycium Barbarum (LB) exhibits anti-ageing and multitarget mechanisms in protecting retinal ganglion cells (RGC) in various animal models. To investigate the therapeutic efficacy of LB glycoproteins (LbGP) in ET-1 induced RGC degeneration, LbGP was applied under pre- and posttreatment conditions to an ET-1 mouse model. Retina structural and functional outcomes were characterised using clinical-based techniques.

METHODS

Adult C57BL/6 mice were randomly allocated into four experimental groups, namely vehicle control (n = 9), LbGP-Pretreatment (n = 8), LbGP-Posttreatment (day 1) (n = 8) and LbGP-Posttreatment (day 5) (n = 7). Oral administration of LbGP 1 mg/Kg or PBS for vehicle control was given once daily. Pre- and posttreatment (day 1 or 5) were commenced at 1 week before and 1 or 5 days after intravitreal injections, respectively, and were continued until postinjection day 28. Effects of treatment on retinal structure and functions were evaluated using optical coherence tomography (OCT), doppler OCT and electroretinogram measurements at baseline, post-injection days 10 and 28. RGC survival was evaluated by using RBPMS immunostaining on retinal wholemounts.

RESULTS

ET-1 injection in vehicle control induced transient reductions in arterial flow and retinal functions, leading to significant RNFL thinning and RGC loss at day 28. Although ET-1 induced a transient loss in blood flow or retinal functions in all LbGP groups, LbGP treatments facilitated better restoration of retinal flow and retinal functions as compared with the vehicle control. Also, all three LbGP treatment groups (i.e. pre- and posttreatments from days 1 or 5) significantly preserved thRNFL thickness and RGC densities. No significant difference in protective effects was observed among the three LbGP treatment groups.

CONCLUSION

LbGP demonstrated neuroprotective effects in a mouse model of ET-1 induced RGC degeneration, with treatment applied either as a pretreatment, immediate or delayed posttreatment. LbGP treatment promoted a better restoration of retinal blood flow, and protected the RNFL, RGC density and retinal functions. This study showed the translational potential of LB as complementary treatment for glaucoma management.

Progressive peripapillary capillary vessel density loss and long-term visual field progression in Normal tension glaucoma

PURPOSE

To explore the association between progressive peripapillary capillary vessel density (pcVD) reduction and the progression of visual field (VF) impairment in individuals with normal tension glaucoma (NTG).

DESIGN

Prospective cohort study.

METHODS

The study enrolled 110 participants with one eye each, totalling 110 NTG eyes. VF defects were evaluated using standard automated perimetry mean deviation (MD), while pcVD measurements were obtained using optical coherence tomography angiography throughout the follow-up period. Estimates of VF progression were determined by event-based and trend-based analyses. Fast VF progression was defined as an MD slope steeper than -0.5 dB/year, while the slow progression or stable VF was defined as an MD slope better or equal to -0.25 dB/year. Linear mixed-effects models were employed to analyse the rates of change in pcVD reduction and VF MD decline over time. Additionally, univariable and multivariable linear models were used to examine the relationship between pcVD changes and VF loss rates in NTG.

RESULTS

Slow VF progression or stable VF was observed in 45% of subjects, while 25% had moderate progression and 30% showed fast progression. Patients with VF progression exhibited faster rate of pcVD reduction in peripapillary global region (-0.73 ± 0.40%/year vs. -0.56 ± 0.35%/year, p = 0.022). Moreover, this rate positively correlated with VF MD decline in NTG (estimate 0.278, 95% CI 0.122-0.433, p = 0.001).

CONCLUSION

In individuals with NTG, faster VF progression was linked to a quicker reduction in pcVD, suggesting a positive correlation between pcVD decline and VF deterioration.

Longitudinal changes in optical coherence tomography angiography characteristics in normal-tension glaucoma with or without high myopia

PURPOSE

To evaluate the structural, microvascular, and functional progression of normal tension glaucoma (NTG) with or without high myopia by examining longitudinal changes in optical coherence tomography angiography (OCTA) and visual field (VF) parameters.

METHODS

We evaluated 61 NTG eyes and classified 25 of the eyes with axial lengths (ALs) of ≥26 mm as highly myopic. We assessed the rate of change in OCTA parameters, namely radial peripapillary capillary (RPC) vessel density (VD), parafovea VD, deep parafovea VD, retinal nerve fibre layer (RNFL) thickness, and ganglion cell complex thickness. We evaluated the correlation of the rate of change in OCTA parameters with VF loss and AL.

RESULTS

Among the 61 NTG eyes, rates of loss of RPC VD, parafovea VD, deep parafovea VD, and RNFL thickness were significantly different from zero despite the nonsignificant rate of change in VF mean deviation (MD). Changes in these OCTA parameters did not differ significantly in highly myopic NTG eyes. The rate of change in VF MD was significantly correlated with the rate of change in parafovea VD in highly myopic and non-highly myopic NTG eyes. In highly myopic NTG eyes, AL was negatively correlated with the rates of loss of RNFL thickness, VF MD, and VF PSD.

CONCLUSION

NTG eyes with a relatively stable VF exhibited loss of VD and RNFL thickness. VF progression in NTG was correlated with decreasing parafovea VD, indicating a structure-function correlation. Greater AL may indicate faster VF loss and RNFL thinning in highly myopic NTG eyes.

Association between glaucoma and stroke: A bidirectional mendelian randomization study

Purpose

Observational studies have reported positive associations between glaucoma and stroke; however, controversial results exist. Importantly, the nature of the relationship remains unknown since previous studies were not designed to test causality. Therefore, we aimed to investigate the possible causal relationships between glaucoma and stroke.

Methods

Our two-sample Mendelian randomization (MR) encompassed multi-ethnic large-scale genome-wide association studies with more than 20000 cases and 260000 controls for glaucoma, and more than 80000 cases and 630000 controls for stroke. Individual effect estimates for each SNP were combined using the inverse-variance weighted (IVW) method. To avoid potential pleiotropic effects, we adjusted the main results by excluding genetic variants associated with metabolic factors. The weighted median and MR-Egger methods were also used for the sensitivity analysis.

Results

Our MR analysis revealed that glaucoma and its subtypes, including primary open-angle glaucoma and primary angle-closure glaucoma, exhibited no causal role in relation to any stroke (AS), any ischemic stroke (AIS), large-artery atherosclerotic stroke (LAS), small-vessel stroke (SVS), or cardioembolic stroke (CES) across MR analyses (all P ​> ​0.05). The null associations remained robust even after adjusting for metabolic-related traits and were consistent in both the European and Asian populations. Furthermore, reverse MR analyses also did not indicate any significant causal effects of AS, AIS, LAS, or CES on glaucoma risk.

Conclusions

Evidence from our series of causal inference approaches using large-scale population-based MR analyses did not support causal effects between glaucoma and stroke. These findings suggest that the relationship of glaucoma management and stroke risk prevention should be carefully evaluated in future studies. In turn, stroke diagnosis should not be simply applied to glaucoma risk prediction.

Utilizing extracellular vesicles as a drug delivery system in glaucoma and RGC degeneration

Retinal diseases are the leading cause of blindness, resulting in irreversible degeneration and death of retinal neurons. One such cell type, the retinal ganglion cell (RGC), is responsible for connecting the retina to the rest of the brain through its axons that make up the optic nerve and is the primary cell lost in glaucoma and traumatic optic neuropathy. To date, different therapeutic strategies have been investigated to protect RGCs from death and preserve vision, yet currently available strategies are restricted to treating neuron loss by reducing intraocular pressure. A major barrier identified by these studies is drug delivery to RGCs, which is in large part due to drug stability, short duration time at target, low delivery efficiency, and undesired off-target effects. Therefore, a delivery system to deal with these problems is needed to ensure maximum benefit from the candidate therapeutic material. Extracellular vesicles (EV), nanocarriers released by all cells, are lipid membranes encapsulating RNAs, proteins, and lipids. As they naturally shuttle these encapsulated compounds between cells for communicative purposes, they may be exploitable and offer opportunities to overcome hurdles in retinal drug delivery, including drug stability, drug molecular weight, barriers in the retina, and drug adverse effects. Here, we summarize the potential of an EV drug delivery system, discussing their superiorities and potential application to target RGCs.

The Role of Optical Coherence Tomography Angiography in Glaucoma

Glaucoma is the leading cause of irreversible vision loss and comprises a group of chronic optic neuropathies characterized by progressive retinal ganglion cell (RGC) loss. Various etiologies, including impaired blood supply to the optic nerve, have been implicated for glaucoma pathogenesis. Optical coherence tomography angiography (OCTA) is a non-invasive imaging modality for visualizing the ophthalmic microvasculature. Using blood flow as an intrinsic contrast agent, it distinguishes blood vessels from the surrounding tissue. Vessel density (VD) is mainly used as a metric for quantifying the ophthalmic microvasculature. The key anatomic regions for OCTA in glaucoma are the optic nerve head area including the peripapillary region, and the macular region. Specifically, VD of the superficial peripapillary and superficial macular microvasculature is reduced in glaucoma patients compared to unaffected subjects, and VD correlates with functional deficits measured by visual field (VF). This renders OCTA similar in diagnostic capabilities compared to structural retinal nerve fiber layer (RNFL) thickness measurements, especially in early glaucoma. Furthermore, in cases where RNFL thickness measurements are limited due to artifact or floor effect, OCTA technology can be used to evaluate and monitor glaucoma, such as in eyes with high myopia and eyes with advanced glaucoma. However, the clinical utility of OCTA in glaucoma management is limited due to the prevalence of imaging artifacts. Overall, OCTA can play a complementary role in structural OCT imaging and VF testing to aid in the diagnosis and monitoring of glaucoma.

Anterior Chamber Air Bubble Dynamics With Decreases in Atmospheric Pressure

PURPOSE

To evaluate the effect of decreasing barometric pressure on intracameral bubble size and intraocular pressure (IOP) in eyes with varying air fills in the anterior chamber.

METHODS

A total of 36 human donor eyes received 30%, 50%, or 90% anterior chamber air fill. The eyes were subjected to decreases in atmospheric pressure down to 750 hPa, equal to 2400 m in altitude, and were repeatedly imaged using anterior segment OCT while IOP was measured continuously.

RESULTS

Eyes with 30% air fill initially showed moderate increases in IOP yet rising to an average of 30.83 mm Hg at 850 hPa (mimicking 1400 m altitude) and 42.08 mm Hg at 750 hPa. Eyes with larger air bubbles showed more acute increases in IOP with increases to an average of 47.25 mm Hg in eyes with 50% air fill at 850 hPa and 63.33 mm Hg at 750 hPa. In eyes with 90% air fill in the anterior chamber, IOP readings with an average of 113.42 mm Hg were observed already at 850 hPa, at which point additional pressure reduction was not performed.

CONCLUSIONS

While severe increases in IOP were observed with decreased atmospheric pressure in eyes with large air bubbles in the anterior chamber, small and moderately sized bubbles seem to allow for travel over modest changes in altitude.

Association of foveal avascular zone change and glaucoma progression

BACKGROUND/AIMS

To investigate the association between longitudinal changes of foveal avascular zone (FAZ) area and the rate of structural and functional progression in glaucoma.

METHODS

A longitudinal cohort included 115 eyes (46 glaucoma suspect and 66 primary open-angle glaucoma) of 81 patients having ≥2 year follow-up, and ≥4 visits with optical coherence tomography angiography and visual field (VF). Eyes in the longitudinal cohort with a slope greater than that found in 95 percentile of separate healthy test-retest series for FAZ area were categorised into FAZ progressors; all other eyes were defined as FAZ non-progressors. A generalised linear mixed-effect model was used to investigate the association of FAZ progressors with demographic and clinical characteristics.

RESULTS

Faster ganglion cell complex (GCC) thinning and faster VF mean deviation (MD) loss were found in eyes with FAZ progressors compared with FAZ non-progressors (mean difference: -0.7 (95% CI, -1.4 to -0.1) µm/y; p=0.026, -0.3 (-0.5 to -0.1) dB/y; p=0.017, respectively), while whole image vessel density was not associated with FAZ progressors (p=0.929). SD of intraocular pressure (IOP) and IOP range were also associated with FAZ progressors in separate multivariable models (OR: 1.54 (1.02 to 2.32) per 1 mm Hg higher, p=0.041; OR: 1.20 (1.01 to 1.41) per 1 mm Hg higher; p=0.035, respectively).

CONCLUSIONS

Significant FAZ increase was weakly associated with moderately faster rates of both GCC thinning and VF MD loss, but not macular vessel density change in glaucoma eyes. Additional studies are needed to elucidate the pathophysiological associations between macula GCC thinning and FAZ area increases in glaucoma.

OCT angiographic evaluation of changes in macula and optic nerve head vessel density after a water drinking test in glaucomatous and healthy eyes

PURPOSE

To evaluate the effects of a water drinking test (WDT) on the intraocular pressure (IOP) and vascular density of the optic nerve head and macula in healthy individuals and those with primary open glaucoma using optical coherence tomography angiography.

METHODS

In this prospective comparative study, 30 healthy patients and 44 POAG subjects were divided into two groups. The study's outcome measures were the IOP and vessel density of the optic nerve and macular area. After ingesting 1000 ml of water in 5 min, the effect of the WDT on the IOP and the vascular density of the macular area and optic nerve head were measured at baseline and then 20, 40, and 60 min later at intervals of 20 min.

RESULTS

The initial IOP in the healthy and glaucomatous eye groups was comparable (15.94 ± 2.6 and 16.87 ± 4.21 mmHg, respectively, P = 0.506). The IOP of both groups peaked at 40' measurements. POAG eyes had significantly higher IOP elevation (4.34 ± 0.30 vs. 2.24 ± 0.30 mmHg, P < 0.001). The glaucomatous eyes had lower radial peripapillary capillary (RPC) and whole macular superficial capillary plexus (SCP) densities at baseline (48.55 ± 5.99 vs. 51.33 ± 3.75) and (48.92 ± 3.41 vs. 45.29 ± 5.29), respectively (P < 0.001). After the WDT, the change in vessel density between groups in the RPC, whole superficial, and deep capillary plexuses was insignificant (SCP and DCP of 0.66 and 0.70, respectively, P = 0.16).

CONCLUSION

The WDT caused a significant IOP jump in both glaucomatous and healthy eyes, but generally, the alterations in the glaucomatous eyes were more pronounced. The changes in vascular density in the macula and optic nerve head were similar between the groups.

Effect of brimonidine on vascular density and imagej-derived flow index of optic nerve head and macula in primary open angle glaucoma

PURPOSE

To study the effect of brimonidine on vascular density and flow index of optic nerve head (ONH) and macula in primary open angle glaucoma (POAG) using optical coherence tomography angiography (OCTA).

METHODS

Twenty-three brimonidine-naïve POAG patients were started on brimonidine. They underwent OCTA ONH and macula before commencing brimonidine and one month thereafter. Systemic arterial blood pressure (SABP) and intraocular pressure (IOP) were measured at each visit to calculate mean ocular perfusion pressure (MOPP). The OCT angiograms were analyzed using ImageJ software to calculate ONH and macular flow indices.

RESULTS

Thirty-seven eyes (23 patients) with a mean age of 56.7 ± 12.49 years were included of whom 60.8% were males. Brimonidine was associated with an increase in the superficial flow index (SFI) (P-value = 0.02) and optic nerve head flow index (ONHFI) (P-value = 0.01). Also, superficial vascular density (SVD) for whole image, superior-hemi and fovea increased (P-value = 0.03, 0.02, 0.03 respectively). ONH inferior-hemi vascular density decreased (P-value = 0.01) despite an increase in inferior quadrant retinal nerve fiber layer thickness (RNFLT) (P-value = 0.03). There was no statistically significant correlation between flow indices and MOPP at baseline and follow-up. A moderate negative correlation was found between SVD and DVD at the fovea and MOPP at baseline and follow-up (P-value = 0.03, 0.05) (P-value = 0.02, 0.01) respectively.

CONCLUSIONS

Brimonidine was associated with an increase in SFI, ONHFI and SVD indicating improved GCC and RNFL perfusion in POAG. Despite the increase in inferior quadrant RNFLT, the concomitant decrease in inferior-hemi ONHVD precluded a conclusion of hemodynamically-mediated improvement of RNFLT.

The Assessment of Radial Peripapillary Capillary Vessel Density in Adult Children of Patients With Primary Open Angle Glaucoma

PRCIS

The observed decrease in radial peripapillary capillary vessel density among adult children of individuals with primary open angle glaucoma, in comparison to controls, suggests the possibility of early microvascular alterations in the eyes of these at-risk individuals.

PURPOSE

To compare the radial peripapillary capillary vessel density (RPCVD) and peripapillary retinal nerve fiber layer (RNFL) thickness values of eyes between healthy adults with a maternal or paternal history of primary open angle glaucoma (POAG) and age-matched healthy controls without a family history of POAG.

MATERIALS AND METHODS

RPCVD values and RNFL thicknesses in the peripapillary region and 4 quadrants (superior, inferior, nasal, and temporal) were evaluated using optical coherence tomography angiography among 30 adult children of patients with POAG and 30 age-matched healthy controls without a family history of POAG.

RESULTS

The mean whole image RPCVD (51.6±1.7% vs. 49.8±1.7%, P =0.0006) and average RPCVD (54.7±1.7% vs. 53.2±2.1%, P =0.006) values were significantly lower in the adult children of patients with POAG compared with age-matched healthy controls without a family history of POAG. There was no difference in terms of RNFL thickness values in any region.

CONCLUSION

Despite having similar RNFL thickness values to the control group, the observation of lower RPCVD in the eyes of adult children of POAG patients may indicate potential early vascular alterations. The result of the present study encourages further longitudinal studies to determine the potential importance of the underlying vascular alterations in these high-risk individuals.

Homer1a reduces inflammatory response after retinal ischemia/reperfusion injury

JOURNAL/nrgr/04.03/01300535-202407000-00042/figure1/v/2023-11-20T171125Z/r/image-tiff

Elevated intraocular pressure (IOP) is one of the causes of retinal ischemia/reperfusion injury, which results in NLRP3 inflammasome activation and leads to visual damage. Homer1a is reported to play a protective role in neuroinflammation in the cerebrum. However, the effects of Homer1a on NLRP3 inflammasomes in retinal ischemia/reperfusion injury caused by elevated IOP remain unknown. In our study, animal models were constructed using C57BL/6J and Homer1flox/ –/Homer1a+/ –/Nestin-Cre+/ – mice with elevated IOP-induced retinal ischemia/reperfusion injury. For in vitro experiments, the oxygen-glucose deprivation/reperfusion injury model was constructed with Müller cells. We found that Homer1a overexpression ameliorated the decreases in retinal thickness and Müller cell viability after ischemia/reperfusion injury. Furthermore, Homer1a knockdown promoted NF-κB P65Ser536 activation via caspase-8, NF-κB P65 nuclear translocation, NLRP3 inflammasome formation, and the production and processing of interleukin-1β and interleukin-18. The opposite results were observed with Homer1a overexpression. Finally, the combined administration of Homer1a protein and JSH-23 significantly inhibited the reduction in retinal thickness in Homer1flox/ –/Homer1a+/ –/Nestin-Cre+/ – mice and apoptosis in Müller cells after ischemia/reperfusion injury. Taken together, these studies demonstrate that Homer1a exerts protective effects on retinal tissue and Müller cells via the caspase-8/NF-κB P65/NLRP3 pathway after I/R injury.

Comparison of Peripapillary Choroidal Thickness Between Primary Open-angle Glaucoma, Normal Tension Glaucoma, and Normal Eyes: A Systematic Review and Meta-analysis

TOPIC

To investigate differences in peripapillary choroidal thickness (PPCT) between primary open-angle glaucoma (POAG), normal tension glaucoma (NTG), and healthy eyes, additionally comparing differences between POAG and NTG eyes.

CLINICAL RELEVANCE

Peripapillary choroidal thickness is a well-established OCT parameter in eyes with glaucoma and other ocular pathologies. The relationship between PPCT and glaucoma, if better understood, may facilitate the development of PPCT as a potential diagnostic and monitoring metric for glaucoma. In particular, there has yet to be a synthesis that directly compares PPCT between POAG eyes and NTG eyes.

METHODS

A comprehensive literature search was performed on PubMed, EMBASE, and Cochrane Library, identifying studies from inception to December 2022. We included studies that measured PPCT using OCT in POAG, NTG, and healthy eyes. Mean difference (MD) among groups was calculated. Statistical analysis was performed using R version 4.2.0. Risk of bias of included studies was assessed using the Newcastle Ottawa Scale (NOS).

RESULTS

Eighteen studies were included in this meta-analysis, with a pooled total of 935 healthy control eyes, 446 NTG eyes, and 934 POAG eyes. There was a significant reduction of PPCT in POAG eyes compared with healthy eyes [MD = -16.32; 95% confidence interval (CI) (-27.55 to -5.09)]. Reduction in PPCT was also significant in NTG eyes compared with healthy eyes [MD = -34.96; 95% CI (-49.97 to -19.95)]. NTG eyes had significantly reduced PPCT compared with POAG eyes [MD = -26.64; 95% CI (-49.00 to -4.28)].

CONCLUSIONS

Glaucomatous eyes appear to have significantly reduced PPCT compared with normal healthy eyes. In addition, PPCT in NTG eyes appear significantly thinner compared with that in POAG eyes.

FINANCIAL DISCLOSURE(S)

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

Incidence and Risk Factors for Retinal Detachment Following Pediatric Cataract Surgery

Background

Retinal detachment is a major postsurgical threat in pediatric cataract surgery; however, the effect of axial length remains unclear. This study aimed to assess the relationship between axial length and detachment risk in vulnerable patients.

Methods

This retrospective cohort study analyzed 132 eyes of 84 pediatric cataract surgery patients aged <20 years old. Axial length was measured preoperatively, and the incidence of retinal detachment was recorded over a median follow-up of 4 years. Logistic regression analysis was used to examine the axial length-detachment relationship.

Results

Twenty eyes had postoperative retinal detachments. The median axial length was longer in the detachment group (23.6 mm) than in the non-detachment group (21.6 mm). Eyes with axial length ≤23.4 mm had 0.55-fold decreased odds of detachment compared to longer eyes. Preexisting myopia and glaucoma confer heightened risk. Approximately half of the patients retained some detachment risk eight years postoperatively.

Conclusion

Shorter eyes (axial length ≤23.4 mm) appear to be protected against pediatric retinal detachment after cataract surgery, whereas myopia, glaucoma, and axial elongation > 23.4 mm elevate the postoperative risk. Understanding these anatomical risk profiles requires surgical planning and follow-up care of children undergoing lensectomy.

Time-Resolved Dynamic Optical Coherence Tomography for Retinal Blood Flow Analysis

Purpose

Optical coherence tomography (OCT) representations in clinical practice are static and do not allow for a dynamic visualization and quantification of blood flow. This study aims to present a method to analyze retinal blood flow dynamics using time-resolved structural OCT.

Methods

We developed novel imaging protocols to acquire video-rate time-resolved OCT B-scans (1024 × 496 pixels, 10 degrees field of view) at four different sensor integration times (integration time of 44.8 µs at a nominal A-scan rate of 20 kHz, 22.4 µs at 40 kHz, 11.2 µs at 85 kHz, and 7.24 µs at 125 kHz). The vessel centers were manually annotated for each B-scan and surrounding subvolumes were extracted. We used a velocity model based on signal-to-noise ratio (SNR) drops due to fringe washout to calculate blood flow velocity profiles in vessels within five optic disc diameters of the optic disc rim.

Results

Time-resolved dynamic structural OCT revealed pulsatile SNR changes in the analyzed vessels and allowed the calculation of potential blood flow velocities at all integration times. Fringe washout was stronger in acquisitions with longer integration times; however, the ratio of the average SNR to the peak SNR inside the vessel was similar across all integration times.

Conclusions

We demonstrated the feasibility of estimating blood flow profiles based on fringe washout analysis, showing pulsatile dynamics in vessels close to the optic nerve head using structural OCT. Time-resolved dynamic OCT has the potential to uncover valuable blood flow information in clinical settings.

Comparing Intraocular Pressure, Ocular Blood Flow, and Retinal Nerve Fiber Layer Thickness in Early and Chronic Hypertensives With Normotensives

PURPOSE

To compare blood pressure (BP), intraocular pressure (IOP), ophthalmic artery flow (OAF) velocity, retinal nerve fiber layer (RNFL) thickness, and visual fields in newly diagnosed hypertension (HT) patients (before treatment), chronic HT (on antihypertensive medications >5 years) and normotensives.

METHODS

A prospective, cross-sectional study at a tertiary care centre in India. Three groups of 45 patients each: group 1 - early HT, group 2 - chronic HT, and Group 3 - normotensives, underwent evaluation of BP, IOP by Goldmann applanation tonometry (GAT), OAF velocity by transcranial doppler (TCD), RNFL analysis by spectral-domain optical coherence tomography (SD-OCT), and visual fields.

RESULTS

The BP was highest in early HT > chronic HT > normotensives (p < 0.001). The IOP of early HT, chronic HT, and normotensives were 15.87 ± 2.19 mmHg, 13.47 ± 1.92 mmHg, and 15.67 ± SD 1.75 mmHg (p < 0.001). The OAF velocity [peak systolic velocity (PSV), end-diastolic velocity (EDV) in cm/sec] was lowest in chronic HT (30.80 ± 7.05, 8.58 ± 1.58) < early HT (35.47 ± 5.34, 10.02 ± 1.74) < normotensives (36.29 ± 4.43, 10.44 ± 2.29), (p < 0.001). The average RNFL thickness was significantly lower in chronic HT (p = 0.022). The PSV, EDV, and MFV showed significant correlation with IOP (r = 0.247, p = 0.004; r = 0.206, p = 0.016; r = 0.266, p = 0.002) and average RNFL thickness (r = 0.309, p= <0.001; r = 0.277, p = 0.001; r = 0.341, p < 0.001).

CONCLUSIONS

Patients with chronic HT demonstrated the lowest retrobulbar flows, IOP and lower RNFL measurements. Lower ocular perfusion may be associated with lower IOP and may be a risk factor for end-organ damage (RNFL) independent of IOP.