Hypertension, perfusion pressure, and primary open-angle glaucoma. A population-based assessment

Ocular microvascular changes in COVID-19: role of hypoxia, D-dimer, IL-6 and systemic treatment

BACKGROUND

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been associated with endothelial dysfunction, which may also compromise the microcirculation within ocular tissues. This prospective study evaluated associations between radial peripapillary capillary (RPC) vessel density (VD) and systemic treatment, age, hypoxia, D-dimer, and interleukin-6 (IL-6) levels in patients recovering from coronavirus disease 2019 (COVID-19) related pneumonia.

METHODS

Sixty-three individuals who were admitted to the hospital due to COVID-19 bilateral pneumonia underwent ophthalmic examination two months post-discharge. RPC VD was measured using optical coherence tomography angiography. Associations with age, arterial hypertension, and systemic treatment (dexamethasone, remdesivir, and oxygen therapy), oxygen saturation, D-dimer, and IL-6 levels were evaluated. The control group comprised 43 control participants with no history of COVID-19 who attended routine ophthalmic examinations.

RESULTS

No ophthalmic abnormalities were detected. RPC VD did not differ significantly with hypertension or systemic treatment with dexamethasone and remdesivir. However, patients receiving oxygen therapy had higher RPC VD. A borderline inverse correlation was observed between inferior RPC VD and age. There were no correlations between RPC VD and oxygen saturation. Significant inverse correlations were found between nasal RPC and mean RPC with D-dimer levels and between inferior RPC VD and IL-6 levels. No significant differences in RPC parameters were observed when comparing the COVID-19 group with controls.

CONCLUSIONS

Hypertension or systemic treatment had no significant effect on RCP VD. However, VD in specific RPC areas correlated inversely with D-dimer and IL-6 levels, highlighting the need for monitoring peripapillary microvasculature for potential long-term ocular effects of COVID-19.

Assessment of the effect of physical activity on intraocular pressure using a novel implanted telemetric pressure sensor

BACKGROUND

Due to technical limitations of commonly used tonometry devices, the effects of physical exercise on intraocular pressure (IOP) have never been studied during exercise. This study continuously monitored IOP variations in patients with glaucoma during physical exercise using an implanted IOP microsensor.

METHODS

In total, 10 participants (six male and four female) with open-angle glaucoma (age range: 67-79), previously implanted with an IOP sensor, were included. We monitored IOP telemetrically during a 10 min session on a bicycle ergometer with a stepwise power increase from 0 to 75 W, in 25 W increments, at 2 min intervals. We also recorded IOP during the 2 min resting period after the exercise compared with resting baseline before exercise.

RESULTS

The average IOP increased from 15.4±1.3 mm Hg at rest to 18.0±1.3 mm Hg at 75 W and returned to 14.4±1.0 mm Hg during the resting period after exercise. During the resting period after the activity, average IOP reduced below baseline in 8 out of 10 patients (ΔIOP=-0.98±0.57 mm Hg, p=0.12). Both systolic blood pressure and heart rate were highly correlated with IOP during the exercise (R²=0.997, p=0.002 and R²=0.986, p=0.007, respectively).

CONCLUSIONS

In our study, IOP, heart rate and blood pressure increased and decreased with physical intensity, suggesting these parameters are closely linked and potentially driven by a common mechanism during aerobic exercise. Further studies with larger patient groups are warranted to better understand the mechanisms involved.

Association of Blood Pressure and Retinal Nerve Fiber Layer Rates of Thinning in Patients with Moderate to Advanced Glaucoma

PURPOSE

To investigate the influence of baseline blood pressure (BP) on retinal nerve fiber layer (RNFL) rates of change (RoCs) in glaucoma patients with central damage or moderate to severe disease.

DESIGN

Prospective cohort study.

PARTICIPANTS

One hundred ten eyes with ≥ 4 RNFL OCT scans and ≥ 2 years of follow-up.

METHODS

Global RNFL RoCs were modeled with a Bayesian hierarchical model with subject- and sector-level random effects. Influence of baseline systolic and diastolic BP measures and their interactions with intraocular pressure (IOP) on global RNFL RoCs was investigated in prognostic models adjusting for relevant baseline demographic and clinical measures.

MAIN OUTCOME MEASURES

Magnitude and direction of coefficients for BP, IOP, and their interaction for prediction of global RNFL RoCs. One-sided Bayesian P values denote posterior probability that a regression coefficient is greater than or less than zero, with P < 0.025 or P > 0.975 defining significance.

RESULTS

Average (standard deviation) 24-2 visual field mean deviation (MD) at baseline, follow-up time, and number of OCT scans were -8.8 (6.0) dB, 4.3 (0.5) years, and 8.3 (1.4), respectively. In multivariable analyses, female sex, Hispanic ethnicity (vs. White ethnicity), better baseline 24-2 MD, higher contrast sensitivity at 12 cycles per degree, presence of diabetes, and thicker central cornea predicted faster RNFL thinning. Adjusted for covariates, lower diastolic BP combined with higher IOP predicted faster RNFL RoCs. Parallel multivariable models incorporating systolic BP showed similar effects. Among various BP/IOP combinations, eyes with IOP at the 90th percentile and diastolic (systolic) BP at 10th percentile demonstrated the fastest RNFL thinning rates (-0.554 and -0.539 μm/year).

CONCLUSIONS

Low BP and higher IOP at baseline predicted faster (worse) RNFL RoCs in glaucoma patients with central damage or moderate to advanced disease. Although there may be potential benefits to BP management in glaucoma patients, the therapeutic value of BP manipulation in glaucoma patients is yet to be established given the proven benefits of tight BP control in reducing cardiovascular morbidity and mortality.

FINANCIAL DISCLOSURE(S)

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

Risk Score Predicting Primary Open-Angle Glaucoma Patients With Vascular Predisposition

Purpose

We tested the hypothesis that a questionnaire-based risk score predicts the prevalence of patients with primary open-angle glaucoma (POAG) with vascular predisposition.

Methods

The Flammer Syndrome Questionnaire (FSQ) was used to determine vascular risk scores in 823 healthy subjects and 512 patients with POAG. Next, we characterized blood flow pulsatility changes within the optic nerve head (ONH) in Flammer syndrome (FS) using laser speckle flowgraphy (LSFG) in 358 eyes of 206 patients with normal-tension glaucoma (NTG). Last, we examined the association between changes in Mean blur rate (MBRAve), an LSFG-derived ONH blood flow measurement, during cold provocation and the FSQ risk score in 56 eyes of 56 patients with NTG.

Results

Five FSQ-related symptoms were significantly associated in patients with POAG patients; cold hands/feet (odds ratio [OR] = 1.82), low blood pressure (BP; OR = 3.29), increased response to drugs (OR = 2.27), underweight (OR = 1.99), and tendency toward perfectionism (OR = 1.88). The vascular risk score showed the best discriminative accuracy in differentiating healthy subjects from patients with NTG (area under the curve [AUC] = 0.73). In the NTG eyes, ONH pulsatile blood flow in the FS group was characterized by greater pulsatility. Moreover, the negative correlation between the high FSQ risk score and the cold-induced ONH blood flow reduction was pronounced in eyes with NTG (correlation coefficient = -0.41).

Conclusions

The FSQ risk score can be a screening tool to identify patients with POAG with increased vascular stiffness and further reduced ONH blood flow during cold stress.

Translational Relevance

The vascular risk score may help tailor individual glaucoma care.

Genetic risk factors associated with ocular perfusion pressure in primary open-angle glaucoma

BACKGROUND

Primary open-angle glaucoma (POAG) is the leading cause of irreversible vision loss. However, its genetic risk factors, such as the vascular hypothesis of POAG, remain unclear. Here, we aimed to explore the genetic associations between mean ocular perfusion pressure (MOPP) and POAG. We performed genome-wide analysis with gene-based analysis from the UK Biobank (N = 459,195), which includes genetic data and ocular phenotypes. Bidirectional two-sample Mendelian randomisation (MR), multivariable MR, and mediation analysis were conducted using summary statistics from a previous meta-analysis of genome-wide association studies (N = 216,257).

RESULTS

CEP85L, GRIA4, GRIN2A, LRFN5, MAGI1, POU6F2, RBFOX1, RBMS1, RBMS3, RBPMS, TRHDE, TUBB3, ZFHX3, and ZMAT4 were significantly correlated with various ocular phenotypes. Furthermore, POAG shared strong genetic associations with corneal resistance factor (CRF), intraocular pressure (IOP), refractive error (RE), and MOPP but none with corneal hysteresis (CH). Univariable MR showed a negative causal effect of CH, CRF, and MOPP and a positive causal effect of IOP on POAG occurrence. In multivariable MR, MOPP exhibited a direct causal effect on POAG, which was supported by the mediation analysis results.

CONCLUSIONS

We successfully determined 14 genetic loci related to CH, CRF, IOP, RE, and MOPP. In univariable and multivaribale MR analyses, a causal effect of MOPP on POAG were observed. In addition, the mediation analysis supported that MOPP exerted direct and indirect causal effects on POAG. This finding indicates that MOPP may serve as a potential causal factor in POAG, providing valuable insights into the pathophysiology of POAG as vascular theory.

Twenty four-hour intraocular pressure fluctuation in treated glaucoma patients: a pilot study

OBJECTIVE

To conduct a pilot study to evaluate and compare the 24-hour habitual intraocular pressure (IOP) and ocular perfusion pressure (OPP) fluctuation in glaucoma patients treated with medical therapy, selective laser trabeculoplasty (SLT) or trabeculectomy.

DESIGN

Pilot study.

PARTICIPANTS

Criteria for inclusion were patients aged 18 years or older with well-controlled IOP with either maximum tolerated medical therapy, previous SLT, or previous trabeculectomy.

METHODS

Recruited patients were admitted to the sleep lab for 24-hour serial habitual IOP and blood pressure measurements. IOP and OPP fluctuation among the 3 treatment groups were compared.

RESULTS

Thirty three (33) eyes from 33 patients were recruited in this study, including 11 patients in the medical therapy group, 11 patients in the SLT group, and 11 patients in the trabeculectomy group. The medical therapy group was found to have significantly higher 24-hour IOP fluctuation (8.3 ± 1.6 mmHg) than the SLT (3.5 ± 1.9 mmHg) and trabeculectomy (4.3 ± 1.3 mmHg) groups (P < 0.001). Mean 24-hour OPP fluctuation was also significantly higher in the medical therapy group (18.5 ± 4.0 mmHg) than the SLT (11.9 ± 7.3 mmHg) and trabeculectomy (14.1 ± 3.9 mmHg) groups (P < 0.05). No difference in IOP or OPP fluctuation was found between SLT and trabeculectomy groups (P > 0.05).

CONCLUSIONS

Both SLT and trabeculectomy may be more effective in reducing 24-hour IOP and OPP fluctuation than medical therapy alone. IOP and OPP fluctuation was comparable between SLT and trabeculectomy cohorts. Future studies are warranted to investigate this further.

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.

The Role of Immune Cells and Signaling Pathways in Diabetic Eye Disease: A Comprehensive Review

Diabetic eye disease (DED) encompasses a range of ocular complications arising from diabetes mellitus, including diabetic retinopathy, diabetic macular edema, diabetic keratopathy, diabetic cataract, and glaucoma. These conditions are leading causes of visual impairments and blindness, especially among working-age adults. Despite advancements in our understanding of DED, its underlying pathophysiological mechanisms remain incompletely understood. Chronic hyperglycemia, oxidative stress, inflammation, and neurodegeneration play central roles in the development and progression of DED, with immune-mediated processes increasingly recognized as key contributors. This review provides a comprehensive examination of the complex interactions between immune cells, inflammatory mediators, and signaling pathways implicated in the pathogenesis of DED. By delving in current research, this review aims to identify potential therapeutic targets, suggesting directions of research for future studies to address the immunopathological aspects of DED.

Predicting 24-hour intraocular pressure peaks and averages with machine learning

Purpose

Predicting 24-hour peak and average intraocular pressure (IOP) is essential for the diagnosis and management of glaucoma. This study aimed to develop and assess a machine learning model for predicting 24-hour peak and average IOP, leveraging advanced techniques to enhance prediction accuracy. We also aimed to identify relevant features and provide insights into the prediction results to better inform clinical practice.

Methods

In this retrospective study, electronic medical records from January 2014 to May 2024 were analyzed, incorporating 24-hour IOP monitoring data and patient characteristics. Predictive models based on five machine learning algorithms were trained and evaluated. Five time points (10:00 AM, 12:00 PM, 2:00 PM, 4:00 PM, and 6:00 PM) were tested to optimize prediction accuracy using their combinations. The model with the highest performance was selected, and feature importance was assessed using Shapley Additive Explanations.

Results

This study included data from 517 patients (1,034 eyes). For predicting 24-hour peak IOP, the Random Forest Regression (RFR) model utilizing IOP values at 10:00 AM, 12:00 PM, 2:00 PM, and 4:00 PM achieved optimal performance: MSE 5.248, RMSE 2.291, MAE 1.694, and R2 0.823. For predicting 24-hour average IOP, the RFR model using IOP values at 10:00 AM, 12:00 PM, 4:00 PM, and 6:00 PM performed best: MSE 1.374, RMSE 1.172, MAE 0.869, and R2 0.918.

Conclusion

The study developed machine learning models that predict 24-hour peak and average IOP. Specific time point combinations and the RFR algorithm were identified, which improved the accuracy of predicting 24-hour peak and average intraocular pressure. These findings provide the potential for more effective management and treatment strategies for glaucoma patients.

Exploring the Relation Between Peripapillary Retinal Vessel Caliber and Visual Field Defects in Primary Open-Angle Glaucoma

Background Primary open-angle glaucoma (POAG) is a progressive optic neuropathy characterized by loss of retinal ganglion cells, optic nerve head changes, and visual field defects. Vascular factors, alongside intraocular pressure, play a crucial role in POAG pathogenesis, and this study aims to explore the relationship between retinal vessel caliber and visual field defects in POAG patients. Purpose To evaluate the association between retinal vessel calibers in the peripapillary area with visual field defects in one or both hemifields. Materials and Methods This cross-sectional study was conducted at a tertiary eye care center in northern Karnataka for one year, enrolling 100 eyes from 50 primary open-angle glaucoma (POAG) patients with visual field abnormalities. Fundus color stereoscopic photographs were taken using a Canon digital camera, and diameters of the superior and inferior temporal arteries (STA and ITA) and veins (STV and ITV) in the peripapillary area were measured. Visual field defects were categorized, and statistical analyses were performed to correlate retinal vessel calibers with field defect locations. Results  Participants had a mean age of 89.68 years, with 72% male. Visual field defects included superior arcuate scotoma (20%), inferior arcuate scotoma (32%), double arcuate scotoma (30%), and tubular vision (18%). Significant vessel caliber changes were observed: for superior hemifield defects, the mean STA: ITA ratio was 1.15 (p = 0.001), and for inferior defects, it was 0.94 (p = 0.04). STV: ITV ratios also showed significant changes corresponding to visual field defects. Eyes with defects in both hemifields showed pronounced narrowing, particularly in inferotemporal vessels. Conclusions Decreased retinal vessel caliber is significantly associated with visual field defects in primary open-angle glaucoma and can be a valuable diagnostic parameter tool for assessing glaucomatous damage and the progression and severity of POAG.

Applications of optical coherence tomography angiography in glaucoma: current status and future directions

Glaucoma is a leading cause of irreversible blindness worldwide, with its pathophysiology remaining inadequately understood. Among the various proposed theories, the vascular theory, suggesting a crucial role of retinal vasculature deterioration in glaucoma onset and progression, has gained significant attention. Traditional imaging techniques, such as fundus fluorescein angiography, are limited by their invasive nature, time consumption, and qualitative output, which restrict their efficacy in detailed retinal vessel examination. Optical coherence tomography angiography (OCTA) emerges as a revolutionary imaging modality, offering non-invasive, detailed visualization of the retinal and optic nerve head microvasculature, thereby marking a significant advancement in glaucoma diagnostics and management. Since its introduction, OCTA has been extensively utilized for retinal vasculature imaging, underscoring its potential to enhance our understanding of glaucoma's pathophysiology, improving diagnosis, and monitoring disease progression. This review aims to summarize the current knowledge regarding the role of OCTA in glaucoma, particularly its potential applications in diagnosing, monitoring, and understanding the pathophysiology of the disease. Parameters pertinent to glaucoma will be elucidated to illustrate the utility of OCTA as a tool to guide glaucoma management.

Plexus-Specific Retinal Capillary Blood Flow Analysis Using Erythrocyte Mediated Angiography and Optical Coherence Tomography Angiography

Purpose

The purpose of this study was to identify and measure plexus-specific absolute retinal capillary blood flow velocity and acceleration in vivo in both nonhuman primates (NHPs) and humans using erythrocyte mediated angiography (EMA) and optical coherence tomography angiography (OCTA).

Methods

EMA and OCTA scans centered on the fovea were obtained in 2 NHPs and 11 human subjects. Scans were also obtained in NHP eyes while IOP was experimentally elevated. Erythrocyte velocity and acceleration in retinal arteries, capillaries, and veins were measured and capillaries were categorized based on location within the superficial vascular (SVP), intermediate capillary (ICP), or deep capillary plexus (DCP). Generalized linear mixed models were used to estimate the effects of intraocular pressure (IOP) on capillary blood flow.

Results

Capillary erythrocyte velocity at baseline IOP was 0.64 ± 0.29 mm/s in NHPs (range of 0.14 to 1.85 mm/s) and 1.55 ± 0.65 mm/s in humans (range of 0.46 to 4.50 mm/s). Mean erythrocyte velocity in the SVP, ICP, and DCP in NHPs was 0.69 ± 0.29 mm/s, 0.53 ± 0.22 mm/s, and 0.63 ± 0.27 mm/s, respectively (P = 0.14 for NHP-1 and P = 0.28 for NHP-2). Mean erythrocyte velocity in the human subjects did not differ significantly among SVP, ICP, and DCP (1.46 ± 0.59 mm/s, 1.58 ± 0.55 mm/s, and 1.59 ± 0.79 mm/s, P = 0.36). In NHPs, every 1 mm Hg increase in IOP was associated with a 0.13 mm/s reduction in arterial velocity, 0.10 mm/s reduction in venous velocity, and 0.01 mm/s reduction in capillary velocity (P < 0.001) when accounting for differences in mean arterial pressure (MAP).

Conclusions

Blood flow by direct visualization of individual erythrocytes can be quantified within capillary plexuses. Capillary velocity decreased with experimental IOP elevation.

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.

Smoking Intensity is Associated With Progressive Optic Nerve Head Vessel Density Loss in Glaucoma

PRCIS

A lifetime history of greater smoking consumption was associated with faster vessel density loss over time. Smoking intensity should be considered when assessing the risk of glaucoma progression, as well as its management.

PURPOSE

To investigate the relationship of smoking and smoking intensity, with the rate of optic nerve head (ONH) whole image capillary density (wiCD) loss in primary open angle glaucoma (POAG) and glaucoma suspect patients.

METHODS

In this longitudinal study, patients with POAG who had at least 2 years of follow-up and optical coherence tomography angiography (OCTA) performed at a minimum of 4 visits were selected for study. The smoking intensity was calculated as the pack-year at the baseline OCTA. Univariable and multivariable linear mixed models were used to determine the effect of each parameter on the rates of wiCD loss over time. Nonlinear least-squares estimation with piecewise regression model was used to investigate the cutoff point for the relationship between wiCD loss and smoking intensity.

RESULTS

One hundred sixty-four eyes (69 glaucoma suspect and 95 POAG) of 110 patients were included with a mean (95% CI) follow-up of 4.0 (3.9 to 4.1) years. Of the 110 patients, 50 (45.5%) had a reported history of smoking. Greater smoking intensity was associated with faster wiCD loss [-0.11 (-0.23 to 0.00)] %/year per 10 pack-year higher; P =0.048) after adjusting for covariates. The wiCD thinning became significantly faster when smoking intensity was greater than 22.2 pack-years. Smoking had no effect on the rate of wiCD thinning in patients who smoked <22.2 pack-years during their lifetime.

CONCLUSIONS

A history of greater smoking consumption was associated with faster vessel density loss, suggesting smoking intensity as a potential risk factor for glaucoma.

Unveiling Novel Structural Biomarkers for the Diagnosis of Glaucoma

Glaucoma, a leading cause of irreversible blindness, poses a significant global health burden. Early detection is crucial for effective management and prevention of vision loss. This study presents a collection of novel structural biomarkers in glaucoma diagnosis. By employing advanced imaging techniques and data analysis algorithms, we now can recognize indicators of glaucomatous progression. Many research studies have revealed a correlation between the structural changes in the eye or brain, particularly in the optic nerve head and retinal nerve fiber layer, and the progression of glaucoma. These biomarkers demonstrate value in distinguishing glaucomatous eyes from healthy ones, even in the early stages of the disease. By facilitating timely detection and monitoring, they hold the potential to mitigate vision impairment and improve patient outcomes. This study marks an advancement in the field of glaucoma, offering a promising avenue for enhancing the diagnosis and possible management.

Possible Causal Association between Type 2 Diabetes and Glycaemic Traits in Primary Open-Angle Glaucoma: A Two-Sample Mendelian Randomisation Study

Existing literature suggests a controversial relationship between type 2 diabetes mellitus (T2D) and glaucoma. This study aimed to examine the potential causal connection between T2D and glycaemic traits (fasting glucose [FG] and glycated haemoglobin [HbA1c] levels) as exposures to primary open-angle glaucoma (POAG) in multi-ethnic populations. Single-nucleotide polymorphisms associated with exposure to T2D, FG, and HbA1c were selected as instrumental variables with significance (p < 5.0 × 10-8) from the genome-wide association study (GWAS)-based meta-analysis data available from the BioBank Japan and the UK Biobank (UKB). The GWAS for POAG was obtained from the meta-analyses of Genetic Epidemiology Research in Adult Health and Aging and the UKB. A two-sample Mendelian randomisation (MR) study was performed to assess the causal estimates using the inverse-variance weighted (IVW) method, and MR-Pleiotropy Residual Sum and Outlier test (MR-PRESSO). Significant causal associations of T2D (odds ratio [OR] = 1.05, 95% confidence interval [CI] = [1.00-1.10], p = 0.031 in IVW; OR = 1.06, 95% CI = [1.01-1.11], p = 0.017 in MR-PRESSO) and FG levels (OR = 1.19, 95% CI = [1.02-1.38], p = 0.026 in IVW; OR = 1.17, 95% CI = [1.01-1.35], p = 0.041 in MR-PRESSO) with POAG were observed, but not in HbA1c (all p > 0.05). The potential causal relationship between T2D or FG and POAG highlights its role in the prevention of POAG. Further investigation is necessary to authenticate these findings.

Normal-Tension Glaucoma and Potential Clinical Links to Alzheimer's Disease

Glaucoma is a group of optic neuropathies and the world's leading cause of irreversible blindness. Normal-tension glaucoma (NTG) is a subtype of glaucoma that is characterized by a typical pattern of peripheral retinal loss, in which the patient's intraocular pressure (IOP) is considered within the normal range (<21 mmHg). Currently, the only targetable risk factor for glaucoma is lowering IOP, and patients with NTG continue to experience visual field loss after IOP-lowering treatments. This demonstrates the need for a better understanding of the pathogenesis of NTG and underlying mechanisms leading to neurodegeneration. Recent studies have found significant connections between NTG and cerebral manifestations, suggesting NTG as a neurodegenerative disease beyond the eye. Gaining a better understanding of NTG can potentially provide new Alzheimer's Disease diagnostics capabilities. This review identifies the epidemiology, current biomarkers, altered fluid dynamics, and cerebral and ocular manifestations to examine connections and discrepancies between the mechanisms of NTG and Alzheimer's Disease.

Impact of smoking on glaucoma

PURPOSE OF REVIEW

Assessing whether lifestyle related factors play a role in causing primary open-angle glaucoma (POAG) is of great value to clinicians, public health experts and policy makers. Smoking is a major global public health concern and contributes to ocular diseases such as cataracts, and age-related macular degeneration through ischemic and oxidative mechanisms. Recently, smoking has been investigated as a modifiable risk factor for glaucoma. In the presence of an association with glaucoma, provision of advice and information regarding smoking to patients may help reduce the burden of disease caused by POAG. Therefore, the aim of this review is to summarize the current evidence regarding the effect of smoking in the pathogenesis of glaucoma and its incidence, progression as well as the benefits of smoking cessation.

RECENT FINDINGS

While the association between glaucoma development and smoking history is controversial, in the last decade, several recent studies have helped to identify possible effects of smoking, especially heavy smoking, in regard to glaucomatous progression. Smoking cessation may possibly be protective against glaucoma progression.

SUMMARY

Smoking may play a role in glaucoma progression and long-term smoking cessation may be associated with lower glaucoma progression. The dose-response relationship between smoking and glaucoma as well as therapeutic potential of smoking cessation needs to be further validated with both preclinical and rigorous clinical studies.

IOP and glaucoma damage: The essential role of optic nerve head and retinal mechanosensors

There are many unanswered questions on the relation of intraocular pressure to glaucoma development and progression. IOP itself cannot be distilled to a single, unifying value, because IOP level varies over time, differs depending on ocular location, and can be affected by method of measurement. Ultimately, IOP level creates mechanical strain that affects axonal function at the optic nerve head which causes local extracellular matrix remodeling and retinal ganglion cell death - hallmarks of glaucoma and the cause of glaucomatous vision loss. Extracellular tissue strain at the ONH and lamina cribrosa is regionally variable and differs in magnitude and location between healthy and glaucomatous eyes. The ultimate targets of IOP-induced tissue strain in glaucoma are retinal ganglion cell axons at the optic nerve head and the cells that support axonal function (astrocytes, the neurovascular unit, microglia, and fibroblasts). These cells sense tissue strain through a series of signals that originate at the cell membrane and alter cytoskeletal organization, migration, differentiation, gene transcription, and proliferation. The proteins that translate mechanical stimuli into molecular signals act as band-pass filters - sensing some stimuli while ignoring others - and cellular responses to stimuli can differ based on cell type and differentiation state. Therefore, to fully understand the IOP signals that are relevant to glaucoma, it is necessary to understand the ultimate cellular targets of IOP-induced mechanical stimuli and their ability to sense, ignore, and translate these signals into cellular actions.

Genetic risk of glaucoma is associated with vascular and retinal nerve fibre wedge defects

PURPOSE

To evaluate the association between localised vascular and retinal nerve fibre layer (RNFL) loss and genetic risk for glaucoma and cardiovascular disease using polygenic risk scores (PRS).

METHODS

858 eyes were included from 455 individuals with suspect and early manifest primary open angle glaucoma. Eyes were characterised as having localised vascular and/or RNFL wedge-shaped defects by scrutiny of optical coherence tomography angiography (OCTA) and OCT images, respectively. Investigations included associations with pre-established scores for genetic risk of glaucoma and cardiovascular disease in the context of glaucoma risk factors and systemic vascular disease outcomes.

RESULTS

Higher genetic risk for glaucoma was associated with both vascular wedge defects and RNFL defects (p < 0.001 and p = 0.020, respectively). A greater genetic risk of glaucoma was associated with the presence of multiple vascular wedges per eye (p = 0.005). Glaucoma progression based on global RNFL loss was associated with vascular and RNFL wedge defects (p ≤ 0.001 and p = 0.008, respectively). The glaucoma PRS was significantly associated with vascular, but not RNFL, wedge defects after controlling for disc haemorrhage (p = 0.007 and p = 0.070, respectively). Vascular wedge defects were not related to the cardiovascular PRS.

CONCLUSION

Individuals with a higher genetic risk of glaucoma based on the PRS were more likely to have retinal vascular defects, as well as structural glaucomatous loss, but this did not relate to systemic cardiovascular risk. This possibly implies a local pathophysiology for the vascular defects in some cases, which may have clinical relevance in the early stages of glaucoma and in individuals at high genetic risk.

Prevalence Ratio of Primary Angle-Closure and Primary Open-Angle Glaucoma in Asian Population: A Meta-Analysis and Multiple Meta-Regression Analysis

PURPOSE

To investigate the prevalence ratio of primary angle-closure glaucoma (PACG) and primary open-angle glaucoma (POAG) in the Asian population.

METHODS

Systematic searches of PubMed, Embase, and Cochrane databases for population-based studies in Asia published until August 5, 2022. We conducted a meta-analysis for PACG to POAG prevalence ratio using inverse variance-weighted random-effects meta-analyses so as to combine the study-specific measures of association. Between-study outcome variation (i.e., heterogeneity) was quantified with the I2 statistic. The multiple meta-regression analyses were performed in order to further account for the reasons for heterogeneity.

RESULTS

Twenty studies, with a total study population of 52,522 individuals, had been conducted in 13 countries. The pooled PACG to POAG prevalence ratio was 2.204 (95% confidence interval, 1.617-3.004) with high heterogeneity (p < 0.001). In multiple meta-regression model, prevalence of POAG is the most important predictor for heterogeneity (model importance, 0.954), followed continent (0.508), and publication year (0.222). For every additional elevation of POAG prevalence (i.e., increase of 1.0%), the PACG to POAG prevalence ratio is expected to rise by 0.471.

CONCLUSIONS

We estimated the pooled PACG to POAG prevalence ratio in the Asian population. The POAG prevalence is the most important factor to determine the PACG to POAG prevalence ratio.

[Primary open angle glaucoma and sleep apnea syndrome: A review of the literature]

The relationship between glaucoma and Obstructive Sleep Apnea Syndrome (OSAS) has long been discussed, with conflicting study findings. OSAS appears in the most recent studies to be more of an aggravating factor than an independent risk factor for glaucoma. Patients with OSAS may develop a more rapid progression of primary open-angle glaucoma (POAG). OSAS may damage the optic nerve not only by increasing the intraocular pressure (IOP) but also by altering the blood supply to the optic nerve as shown by more recent work with OCT-Angiography. Although the systemic benefits of Continuous Positive Airway Pressure (CPAP) have been demonstrated, few studies have evaluated its effect on the optic nerve. CPAP might act on glaucomatous neuropathy by improving the blood supply to the optic nerve. The study of this mechanism of action might provide new insights into the relationship between OSAS and glaucoma.

Topographic comparison of the retinal microvascular changes between patients with compressive and glaucomatous optic neuropathies

We investigated the difference in optical coherence tomography angiography characteristics between the patients with compressive optic neuropathy (CON, n = 26) and glaucomatous optic neuropathy (GON, n = 26), who were matched for the severity of visual field defect. The peripapillary retinal nerve fiber layer (pRNFL) thickness in the nasal and temporal sectors was thinner in the CON group, whereas the inferior pRNFL thickness was thinner in the GON group. Accordingly, the CON group had lower peripapillary vessel density (pVD) in the nasal and temporal sectors, and the GON group in the inferior sector. In the macular area, the CON group had a thinner macular ganglion cell-inner plexiform layer in the superior and nasal sectors, whereas the GON group in the inferior sector. However, the CON group did not have a lower macular VD than the GON group in any sector, whereas the GON group exhibited lower superficial capillary plexus VD in the superior, inferior, and temporal sectors. Comparison of the structure-vasculature correlation revealed a significant difference in the nasal and temporal peripapillary areas and superior and nasal macular sectors; a decrease in VD was greater in the GON group than in the CON group when the comparable structural change occurred.

Long-term HIF-1α stabilization reduces respiration, promotes mitophagy, and results in retinal cell death

Ocular hypertension during glaucoma can lead to hypoxia, activation of the HIF transcription factors, and a metabolic shift toward glycolysis. This study aims to test whether chronic HIF activation and the attendant metabolic reprogramming can initiate glaucoma-associated pathology independently of ocular hypertension. HIF-1α stabilization was induced in mice for 2 and 4 weeks by inhibiting prolyl hydroxylases using the small molecule Roxadustat. HIF-1α stabilization and the expression of its downstream bioenergetic targets were investigated in the retina by immunofluorescence, capillary electrophoresis, and biochemical enzyme activity assays. Roxadustat dosing resulted in significant stabilization of HIF-1α in the retina by 4 weeks, and upregulation in glycolysis-associated proteins (GLUT3, PDK-1) and enzyme activity in both neurons and glia. Accordingly, succinate dehydrogenase, mitochondrial marker MTCO1, and citrate synthase activity were significantly decreased at 4 weeks, while mitophagy was significantly increased. TUNEL assay showed significant apoptosis of cells in the retina, and PERG amplitude was significantly decreased with 4 weeks of HIF-1α stabilization. A significant increase in AMPK activation and glial hypertrophy, concomitant with decreases in retinal ganglion cell function and inner retina cell death suggests that chronic HIF-1α stabilization alone is detrimental to retina metabolic homeostasis and cellular survival.

Incidence Rates and Risk Ratios of Normal Tension Glaucoma in Patients with Chronic Rhinosinusitis: A Population-Based Longitudinal Follow-Up Study

Several studies have investigated the association between chronic rhinosinusitis (CRS) and ophthalmological complications. However, it remains uncertain whether CRS is independently associated with the development of normal tension glaucoma (NTG). Therefore, this retrospective cohort study aimed to investigate the prospective association between CRS and the increased incidence and risk of NTG using a representative population-based dataset. The selection of both the CRS and comparison groups was meticulously conducted through the propensity scoring method. The incidence and risk ratios of NTG were measured using person-years at risk and a weighted Cox proportional hazards model. We enrolled 30,284 individuals without CRS (comparison group) and 15,142 individuals with CRS. The NTG incidence rates were 1.19 and 0.81 in the CRS and comparison groups, respectively. The CRS group showed a significantly increased risk of subsequent development for NTG (adjusted hazard ratio = 1.41, 95% confidence interval = 1.16-1.72), regardless of the CRS subtype. Additionally, the risk of developing NTG was relatively higher in the first 2 years after CRS diagnosis. Moreover, a subgroup analysis revealed a higher risk of NTG in elderly female individuals with CRS. The present findings underscore the importance of monitoring and managing NTG risk in individuals with CRS, especially in elderly female patients.

Association Between Alcohol Consumption Patterns and Glaucoma in Japan

PRCIS

In this case-control study of the Japanese population, including 3207 glaucoma cases, alcohol consumption patterns such as frequency and quantity showed a positive association with glaucoma prevalence.

PURPOSE

To examine the association between alcohol consumption patterns and glaucoma.

SUBJECTS AND METHODS

This case-control study evaluated 3207 cases with glaucoma and 3207 matched controls. Patients over 40 years of age were included from 1,693,611 patients admitted to 34 hospitals in Japan. Detailed alcohol consumption patterns (drinking frequency, average daily drinks, and total lifetime drinks) were obtained, as well as various confounding factors, including smoking history and lifestyle-related comorbidities. Conditional logistic regression models were used to calculate odds ratios (ORs) and 95% CIs for glaucoma prevalence.

RESULTS

Drinking frequency showed an association with glaucoma for "a few days/week" (OR, 1.19; 95% CI, 1.03-1.38) and "almost every day/week" (OR, 1.40; 95% CI, 1.18-1.66). Average daily drinks showed an association for ">0-2 drinks/day" (OR, 1.16; 95% CI, 1.03-1.32). Total lifetime drinks showed an association for ">60-90 drink-year" (OR, 1.23; 95% CI, 1.01-1.49) and ">90 drink-year" (OR, 1.23; 95% CI, 1.05-1.44). As alcohol consumption levels differed considerably between men and women, additional analyses were conducted separately for men and women. Among men, drinking frequency of "a few days/week" and "almost every day/week," average daily drinks of ">0-2 drinks/day" and ">2-4 drinks/day," and total lifetime drinks of ">60-90 drink-year" and ">90 drink-year" had an association with glaucoma. Conversely, among women, neither drinking frequency, average daily drinks, nor total lifetime drinks were associated.

CONCLUSIONS

Both the frequency and quantity of alcohol consumption were associated with glaucoma. Further research on gender differences is warranted.

Low Ocular Perfusion Pressure Values at Rest and during Resistance Exercise in Offspring of Glaucoma Patients

Purpose

To compare the ocular perfusion pressure (OPP) response during physical exercise in individuals with and without a family history (FH+, FH-) of glaucoma.

Methods

Thirty-four subjects, divided into FH+ and FH- groups, realized 3 min at rest, 3 min of isometric handgrip exercise at 30% of maximal voluntary contraction, followed by 3 min of recovery. Blood pressure (Dixtal® automatic device) and intraocular pressure (Goldmann applanation tonometer) were measured during rest, exercise, and recovery. The mean OPP (mOPP) was calculated.

Results

In the FH+ group (17 subjects), baseline mOPP values were significantly lower than in the FH- group (17 subjects) (right eye: P < 0.001, left eye: P < 0.001, respectively). During exercise, both the FH+ and FH- groups showed a similar increase in mOPP in both eyes (right eye: FH+: 38 ± 4 mmHg vs. 51 ± 7 mmHg, FH-: 48 ± 5 mmHg vs. 57 ± 9 mmHg, P < 0.001; left eye: FH+: 39 ± 3 mmHg vs. 51 ± 7 mmHg; FH-: 46 ± 5 mmHg vs. 58 ± 8 mmHg, P < 0.001, respectively). However, the FH+ group maintained significantly lower mOPP values compared to the FH- group in the right and left eyes (group effect: P = 0.002, P = 0.002, respectively). The percentage of increase in mOPP in the FH+ group was greater compared to the FH- group during exercise (right eye: 34.1% ± 15.9% vs. 22.1% ± 13.2%, respectively; P = 0.025; left eye: 33.2% ± 17.7% vs. 22.4% ± 13.7%, respectively, P = 0.056).

Conclusions

mOPP increased during physical exercise in both groups, but the FH+ group had lower absolute values. In addition, the FH+ group appears to demonstrate a higher percentage increase in mOPP compared to the FH- group.

Diurnal change of retinal vessel density related to hemodynamic variation in treatment-naïve low-teens normal-tension glaucoma

This study undertook to investigate the diurnal variation of optical coherence tomography angiography (OCTA) -derived retinal vessel density (RVD) in glaucoma patients with low baseline intraocular pressure (IOP). A prospective evaluation was performed on low-teens normal-tension glaucoma (low-teens NTG) patients with pre-treatment IOP < 15 mmHg and 32 healthy subjects. Superficial peripapillary and macular RVD by OCTA, IOP, and systemic blood pressure (BP) were all measured four times per day (from 9:00 a.m. to 6:00 p.m.). In the low-teens NTG group, the magnitude of diurnal changes in peripapillary RVD and macular RVD were greater than those in the healthy group. Diurnal variations of diastolic BP (DBP) and mean ocular perfusion pressure (MOPP) also were greater in the low-teens NTG group. As for the patterns of diurnal RVD change, the inferior and temporal sections of macular RVD showed significant differences between the two groups. Diurnal changes of RVD and MOPP and were greater than those in healthy eyes. The macular RVD and MOPP showed different diurnal patterns between the two groups. From these findings, OCTA-derived RVD variation could be related to hemodynamic variability in low-teens NTG.

Super-Resolution Ultrasound Localization Microscopy Using High-Frequency Ultrasound to Measure Ocular Perfusion Velocity in the Rat Eye

Imaging of the ocular vasculature can provide new insights into the pathophysiology of ocular diseases. This study proposes a novel high-frequency super-resolution ultrasound localization microscopy (SRULM) technique and evaluates its ability to measure in vivo perfusion changes in the rat eye at elevated intraocular pressure (IOP). A 38.4 MHz center frequency linear array transducer on a VisualSonics Vevo F2 imaging platform was used to collect high frame rate (1 kHz) radiofrequency data of the posterior rat eye following systemic microbubble contrast injection. Following clutter and spatiotemporal non-local means filtering, individual microbubbles were localized and tracked. The microbubble tracks were accumulated over 10,000 frames to generate vascular images quantifying perfusion velocity and direction. Experiments were performed using physiologic relevant controlled flow states for algorithm validation and subsequently performed in vivo on the rat eye at 10 mm Hg IOP increments from 10 to 60 mm Hg. The posterior vasculature of the rat eye, including the ophthalmic artery, long posterior ciliary arteries and their branches, central retinal artery and retinal arterioles and venules were successfully visualized, and velocities quantified at each IOP level. Significant reductions in arterial flow were measured as IOP was elevated. High-frequency SRULM can be used to visualize and quantify the perfusion velocity of the rat eye in both the retrobulbar and intraocular vasculature simultaneously. The ability to detect ocular perfusion changes throughout the depth of the eye may help elucidate the role ischemia has in the pathophysiology of ocular diseases such as glaucoma.

Peripheral Microvascular Abnormalities Associated with Open-Angle Glaucoma

PURPOSE

To investigate peripheral microvascular abnormalities associated with patients with open-angle glaucoma (OAG).

DESIGN

This was a cross-sectional study.

PARTICIPANTS

Patients with OAG and controls.

METHODS

All subjects underwent detailed ophthalmic evaluation, including Humphrey visual field (HVF) tests and swept source OCT. To evaluate peripheral microvascular abnormalities, nailfold capillaroscopy (NFC) and laser Doppler imaging (LDI) were performed. The presence of microhemorrhages, tortuous capillaries, dilated capillaries, avascular areas, and the capillary density, among other characteristics, were recorded using NFC; fingertip blood flow (FBF) was measured using LDI at different time points, before and 1, 10, and 20 minutes after exposure to a cold stimulus. In addition, venous blood samples were collected to measure serum endothelin-1 (ET-1) concentrations as well as serum autoantibodies.

MAIN OUTCOME MEASURES

Presence of microhemorrhages, tortuous capillaries, and dilated capillaries; FBF; ET-1; and autoantibodies.

RESULTS

Sixty-eight subjects (43 patients with OAG and 25 controls) were enrolled in the study. Microhemorrhages were found in the nail bed of 65.1% of the patients with OAG compared with 25.0% of the controls (P = 0.003). There was a significant difference in the mean FBF at the baseline in patients with OAG versus controls (293.6 ± 100.2 vs 388.8 ± 52.0 perfusion units, respectively, P < 0.001), together with a significant decrease in the mean FBF 10 and 20 minutes after cold stimulus in patients with OAG in comparison to controls (P < 0.001 for all comparisons). There was a positive correlation between mean baseline FBF and HVF mean deviation (r = 0.27, P = 0.03) and between mean baseline FBF and average retinal nerve fiber layer thickness (r = 0.44, P = 0.001). Neither the analysis of ET-1 concentrations (P= 0.71) nor the autoantibodies measurements (P > 0.05, for all) showed any difference between the 2 groups.

CONCLUSIONS

Significant peripheral microvascular abnormalities were found in patients with OAG compared to controls, suggesting that microvascular changes might play a role in the pathogenesis of the disease. In addition, part of these peripheral microvascular abnormalities seems to be correlated with both functional and structural glaucomatous damage.

FINANCIAL DISCLOSURE(S)

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

Association of Blood Pressure With Rates of Macular Ganglion Cell Complex Thinning in Patients With Glaucoma

Importance

There are scarce data on the association of blood pressure measures with subsequent macular structural rates of change in patients with glaucoma.

Objective

To investigate the association of baseline blood pressure measures with rates of change of the macular ganglion cell complex in patients with central or moderate to advanced glaucoma damage at baseline.

Design, Setting, and Participants

This prospective cohort study, conducted from August 2021 to August 2022, used data from patients in the Advanced Glaucoma Progression Study at the University of California, Los Angeles. Participants were between 39 and 80 years of age and had more than 4 macular imaging tests and 2 or more years of follow-up.

Exposures

A diagnosis of glaucoma with either central damage or a visual field mean deviation worse than -6 dB.

Main Outcomes and Measures

The main outcome was the association of blood pressure measures with ganglion cell complex rates of change. Macular ganglion cell complex thickness rates of change were estimated with a bayesian hierarchical model. This model included relevant demographic and clinical factors. Blood pressure measures, intraocular pressure, and their interactions were added to the model to assess the association of baseline blood pressure measures with global ganglion cell complex rates of change.

Results

The cohort included 105 eyes from 105 participants. The mean (SD) age, 10-2 visual field mean deviation, and follow-up time were 66.9 (8.5) years, -8.3 (5.3) dB, and 3.6 (0.4) years, respectively, and 67 patients (63.8%) were female. The racial and ethnic makeup of the cohort was 15 African American (14.3%), 23 Asian (21.9%), 12 Hispanic (11.4%), and 55 White (52.4%) individuals based on patient self-report. In multivariable analyses, female sex, history of taking blood pressure medications, higher intraocular pressure, thicker central corneal thickness, shorter axial length, higher contrast sensitivity at 12 cycles per degree, and higher baseline 10-2 visual field mean deviation were associated with faster ganglion cell complex thinning. Lower diastolic blood pressure was associated with faster rates of ganglion cell complex thinning at higher intraocular pressures. For intraocular pressures of 8 and of 16 mm Hg (10% and 90% quantiles, respectively), every 10 mm Hg-lower increment of diastolic blood pressure was associated with 0.011 μm/y slower and -0.130 μm/y faster rates of ganglion cell complex thinning, respectively.

Conclusions and Relevance

In this cohort study, a combination of lower diastolic blood pressure and higher intraocular pressure at baseline was associated with faster rates of ganglion cell complex thinning. These findings support consideration of evaluating and addressing diastolic blood pressure as a therapeutic measure in patients with glaucoma if supported by appropriate clinical trials.

Associations of Midlife and Late-Life Blood Pressure Status With Late-Life Retinal OCT Measures

Purpose

To explore the relationship of long-term blood pressure (BP) patterns with late-life optical coherence tomography (OCT) structural measures reflecting optic nerve health.

Methods

Participants in this community-based cohort study of black and white individuals were part of the Atherosclerosis Risk in Communities study and the nested Eye Determinants of Cognition (EyeDOC) study. Participants had BP measured six times from 1987 to 2017 and were categorized into five BP patterns: sustained normotension; midlife normotension, late-life hypertension (systolic BP [SBP] >140 mmHg or diastolic BP [DBP] >90 mmHg or antihypertensive medication use); sustained hypertension; midlife normotension, late-life hypotension (SBP <90 mmHg or DBP <60 mmHg); and midlife hypertension, late-life hypotension. Multivariable linear regression modeling was used to evaluate associations between BP patterns and late-life OCT ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer (RNFL) thickness.

Results

In total, 931 eyes of 931 participants (mean age at EyeDOC visit = 80 years; 63% female; 45% black) were included. Mean GCC and RNFL thicknesses in the sustained normotension pattern were 90.8 ± 10.3 µm and 89.9 ± 11.2 µm versus 89.4 ± 11.9 µm and 90.1 ± 12.2 µm in the sustained hypertension pattern (P > 0.05). Compared to the sustained normotension pattern, no significant differences in GCC or RNFL thickness were found for any anomalous BP pattern.

Conclusions

Assessment of long-term BP status showed no significant associations with late-life OCT structural measures.

Translational Relevance

OCT imaging results in our population-based sample suggest that neither hypertension, even when present in midlife, nor late-life hypotension are significant risk factors for late-life optic nerve damage.

Individualized Treatment for Glaucoma Patients with Diabetes mellitus

Glaucoma and diabetes mellitus are two common chronic diseases in Europe and worldwide which require intensive therapy. Various pathophysiological mechanisms have been discussed which favour the development of glaucoma, especially in the presence of diabetes mellitus. Medicinal and surgical adjustment of intraocular pressure is associated with some limitations in patients with diabetes mellitus, for example, filtering interventions show lower success rates than in non-diabetic glaucoma patients. Besides pure ophthalmological endocrinological therapy, the psychological burden of two chronic diseases should also be considered and included in the individual therapy plan.

Long-term effects of obstructive sleep apnea and its treatment on open-angle glaucoma: a big-data cohort study

STUDY OBJECTIVES

The relationship between open-angle glaucoma (OAG) and obstructive sleep apnea (OSA) is unclear. The long-term risk for OAG after OSA diagnosis has not been investigated. Therefore, we assessed the risk for OAG among patients with OSA over a 12-year follow-up period using nationwide, population-based data.

METHODS

The OSA group was randomly selected from among 3.5 million individuals registered with the National Health Insurance Service. The non-OSA group was obtained through propensity score matching considering several variables. The primary endpoint was glaucoma diagnosis.

RESULTS

The OSA and non-OSA groups both included 6,369 individuals. The overall hazard ratio for OAG in the OSA group was 1.42 (95% confidence interval [CI]: 1.19-1.69). In subgroup analysis, the hazard ratio for OAG was 1.94 (95% CI: 1.57-2.41) for those aged > 60 years, 1.50 (95% CI: 1.20-1.89) for those with diabetes mellitus, 1.53 (95% CI: 1.26-1.86) for those with hypertension, and 0.71 (95% CI: 0.52-0.96) for those with a history of OSA surgery.

CONCLUSIONS

Over the 12-year follow-up, the risk for OAG increased after OSA diagnosis. Further research will be necessary to determine if treating OSA can mitigate this association.

CITATION

Lee T-E, Kim JS, Yeom SW, Lee MG, Lee JH, Lee H-J. Long-term effects of obstructive sleep apnea and its treatment on open-angle glaucoma: a big-data cohort study. J Clin Sleep Med. 2023;19(2):339-346.

[Assessment of environmental and genetic risk factors for the development of primary open-angle glaucoma]

Primary open-angle glaucoma (POAG) is a multifactorial disease with both environmental and genetic factors involved in its pathogenesis.

PURPOSE

The study evaluates the role of a number of environmental and genetic risk factors in the risk of POAG development and builds a prognostic model.

MATERIAL AND METHODS

The study group included 197 patients aged 44 to 90 years (98 - patients with POAG, 99 - the control group), who were treated in the Republican Clinical Ophthalmological Hospital of the Ministry of Health of the Republic of Tatarstan named after Prof. E.V. Adamyuk.

RESULTS

Age, family history of the disease, presence of type 2 diabetes mellitus, arterial hypertension were revealed to be associated with an increased risk of POAG development. The polymorphisms of matrix metalloproteinase MMP9 and vitamin D receptor (VDR) genes were shown to influence the development of POAG. The prognostic model considering these factors had high sensitivity and specificity (72.0% and 82.6% respectively).

CONCLUSION

The prognostic model based on environmental and genetic factors is important for assessing the risk of POAG and early detection of the disease.

Efficacy of dorzolamide in improving ocular blood flow in patients with open-angle glaucoma: The Indian carbonic anhydrase inhibitor trial

Purpose

Impaired ocular blood flow is an important risk factor in the pathogenesis of open-angle glaucoma (OAG). Studies have reported that dorzolamide 2% may be effective in improving ocular blood flow (OBF) in OAG patients. The objective of this study was to determine the efficacy of dorzolamide 2% (DORZOX, Cipla Ltd.) in improving retrobulbar blood flow in an Indian setting.

Methods

The study was conducted as an interventional pilot project in 24 healthy subjects and 19 OAG patients. Baseline OBF measurements were done for all glaucoma patients with color Doppler imaging (CDI). Baseline ocular perfusion pressure (OPP) was calculated for all participants. Glaucoma patients were given dorzolamide 2% thrice daily for 12 weeks. The primary efficacy endpoints were mean changes in the CDI parameters of the retrobulbar vessels and OPP posttreatment. The secondary endpoint was mean change in the intraocular pressure (IOP) and adverse events, if any.

Results

In comparison to healthy subjects, glaucoma patients displayed significantly reduced baseline OPP (P = 0.002). Treatment with dorzolamide 2% for 12 weeks led to a significant increase in OPP (P < 0.001) and a significant increase in end diastolic velocity (EDV) in all major ophthalmic arteries like ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary artery (SPCA) (P < 0.001, P = 0.04, and P = 0.0075, respectively). A significant reduction in the intraocular pressure (IOP; P = 0.007) was observed posttreatment, with no adverse events reported.

Conclusion

Dorzolamide 2% significantly improved parameters such as the EDV and OPP in major ophthalmic arteries. This pilot study shows promising results on using dorzolamide for treating Indian patients with OAG.

Fractal Dimension of Peripapillary Vasculature in Primary Open-Angle Glaucoma

PURPOSE

To compare the fractal dimensions of the peripapillary microvasculature as obtained by optical coherence tomography angiography (OCTA) between primary open-angle glaucoma (POAG) and controls.

METHODS

Optic nerve head and peripapillary area images were taken using the 20° × 20°-scan of Spectralis OCTA (Heidelberg Engineering) in 97 subjects (64 POAG patients, 33 control patients). The optic nerve head microvasculature was evaluated according to predefined slabs: the superficial vascular complex (SVC) and the avascular complex (AVC). The en face image of each slab was processed by ImageJ software (National Institutes of Health) in order to calculate the vessel density and the fractal dimension using the box-counting method. For comparison, the peripapillary retinal nerve fiber layer (RNFL) thickness was obtained from Spectralis OCT circle scans. The utilities of the parameters for discriminating between the POAG and control groups were assessed using areas under the receiver operating characteristic curves (AUCs).

RESULTS

The SVC fractal dimension was lower in the POAG than in the control group (p < 0.001), while AVC showed no intergroup difference (p = 0.563). The fractal dimension showed a good correlation with the vessel density in both SVC and AVC (both p < 0.001). In a multivariable regression analysis, the SVC fractal dimension was negatively correlated with age (p < 0.001) and axial length (p < 0.001) and positively correlated with average RNFL thickness (p < 0.001), while the AVC fractal dimension was positively correlated with the Bruch's membrane opening size (p = 0.013). In terms of diagnostic utility, the AUC was significantly larger for the average RNFL thickness (AUC, 0.889) than for the SVC fractal dimension (AUC, 0.772; p = 0.008).

CONCLUSIONS

The fractal dimension of SVC was associated with the average RNFL thickness and was reduced in POAG patients. Fractal dimension analysis could be used in evaluating peripapillary vascularity by OCTA.

Relationship between blood pressure and intraocular pressure in the JPHC-NEXT eye study

Although a positive link between hypertension and intraocular pressure (IOP) has been suggested, the individual effects of systolic and diastolic blood pressure (SBP and DBP, respectively) on IOP remain unclear, particularly among Japanese populations. Here, we conducted a large-scale, cross-sectional study to determine individual and combined effects of SBP/DBP and hypertension on IOP. In total, 6783 Japanese people aged over 40 years underwent systemic and ophthalmological examinations, including measurements of blood pressure and IOP, conducted using non-contact tonometers. After adjusting for a priori known confounding factors, SBP and DBP levels were found to be positively correlated with IOP levels. The multivariable-adjusted odds ratio when comparing the hypertensive and normotensive groups for the prevalence of ocular hypertension was 1.88 (95% confidence interval, 1.14-3.08). When analysing the combined effects of SBP and DBP on ocular hypertension, SBP elevation had a greater effect on ocular hypertension than DBP increase. In conclusion, SBP and DBP levels and the prevalence of systemic hypertension were found to be positively associated with IOP levels and the prevalence of ocular hypertension in an ophthalmologically healthy Japanese population. Our findings suggest that systemic blood pressure control may be key for controlling IOP.

Ocular pulse amplitude and visual field changes in patients diagnosed with aortic regurgitation

PURPOSE

To examine whether there is a relationship between ocular pulse amplitude (OPA), intraocular pressure (IOP), and visual field (VF) deterioration among the patients diagnosed with aortic regurgitation (AR).

METHODS

Twenty-nine patients (average age of 62.06 ± 13.27 years) with AR diagnosis without glaucoma history as AR group and 32 healthy participants (average age 63.81 ± 6.42 years) as control group were included in the study. Routine ophthalmologic examination including VF test [mean deviation (MD), pattern standard deviation (PSD) and VF index (VFI) values were recorded], diurnal IOP and OPA measurements with Pascal dynamic contour tonometry (DCT) was conducted on the patients. VF deficits were classified by Glaucoma Staging System 2 (GSS 2) score.

RESULTS

Sixteen (50.0%) of 32 healthy subjects and 14 (48.3%) of 29 AR patients were female (p = 1.000). The measurement conducted at 15:30 among the diurnal IOP measurements performed with the Pascal DCT was found to be statistically significantly higher in the AR group (p = 0.009). While the MD and PSD values of the group diagnosed with AR were determined to be statistically significantly high, the VFI value was found to be significantly low. When the healthy cases and the patients diagnosed with AR were compared, it was observed that there was a statistically significant positive correlation in terms of the significant GSS 2 stage (p < 0.001).

CONCLUSION

Although there was no significant increase in IOP, VF deficits were detected in patients with AR. These VF pathologies may be due to the ocular perfusion disorder in AR. However, additional comprehensive studies that also examine perfusion are needed to further confirm this.

Ocular Pulse Amplitude Correlates With Ocular Rigidity at Native IOP Despite the Variability in Intraocular Pulse Volume With Each Heartbeat

Purpose

The purpose of this study was to assess ocular coat mechanical behavior using controlled ocular microvolumetric injections (MVI) of 15 µL of balanced salt solution (BSS) infused over 1 second into the anterior chamber (AC) via a syringe pump.

Methods

Intraocular pressure (IOP) was continuously recorded at 200 Hz with a validated implantable IOP telemetry system in 7 eyes of 7 male rhesus macaques (nonhuman primates [NHPs]) during 5 MVIs in a series at native (3 trials), 15 and 20 mm Hg baseline IOPs, repeated in 2 to 5 sessions at least 2 weeks apart. Ocular rigidity coefficients (K) and ocular pulse volume (PV) were calculated for each trial. Data were averaged across sessions within eyes; PV was analyzed with a three-level nested ANOVA, and parameter relationships were analyzed with Pearson Correlation and linear regression.

Results

After MVI at native baseline IOP of 10.4 ± 1.6 mm Hg, IOP increased by 9.1 ± 2.8 mm Hg (∆IOP) at a 9.6 ± 2.7 mm Hg/s slope, ocular pulse amplitude (OPA) was 0.70 ± 0.13 mm Hg on average; the average K was 0.042 ± 0.010 µL-1 and average PV was 1.16 ± 0.43 µL. PV varied significantly between trials, days, and eyes (P ≤ 0.05). OPA was significantly correlated with K at native IOP: Pearson coefficients ranged from 0.71 to 0.83 (P ≤ 0.05) and R2 ranged from 0.50 to 0.69 (P ≤ 0.05) during the first trial.

Conclusions

The MVI-driven ∆IOP and slope can be used to assess ocular coat mechanical behavior and measure ocular rigidity.

Translational Relevance

Importantly, OPA at native IOP is correlated with ocular rigidity despite the significant variability in PV between heartbeats.

Effects of Smoking on Optic Nerve Head Microvasculature Density in Glaucoma

PRCIS

Decreased superficial whole image capillary density was observed in open angle glaucoma (OAG) patients with high smoking intensity.

PURPOSE

To investigate the effects of smoking on optic nerve head capillary density measured by optical coherence tomography angiography in patients with OAG.

METHODS

In this retrospective cross-sectional study, perimetric and preperimetric glaucoma patients enrolled in the Diagnostic Innovations in Glaucoma Study (DIGS) with optical coherence tomography angiography follow-up were included. Univariable and multivariable linear mixed analysis were performed to determine the effects of different variables on the superficial whole image capillary density.

RESULTS

A total of 432 eyes of 271 glaucoma patients comprising 63 preperimetric (106 eyes) and 208 perimetric OAG (326 eyes) were included. A history of tobacco consumption was reported in 105 (38.8%). Among smokers, mean (95% confidence interval) smoking intensity was 12.8 (10.2, 15.5) pack-years. After adjusting for age, glaucoma severity and other confounders, each 10 pack-year increase in smoking intensity (95% confidence interval) was associated with -0.54 (-1.06, -0.02) % lower whole image capillary density ( P =0.041).

CONCLUSIONS

Smoking intensity is associated with reduced optic nerve vessel density in glaucoma.

Eye-specific 3D modeling of factors influencing oxygen concentration in the lamina cribrosa

Our goal was to identify the factors with the strongest influence on the minimum lamina cribrosa (LC) oxygen concentration as potentially indicative of conditions increasing hypoxia risk. Because direct measurement of LC hemodynamics and oxygenation is not yet possible, we developed 3D eye-specific LC vasculature models. The vasculature of a normal monkey eye was perfusion-labeled post-mortem. Serial cryosections through the optic nerve head were imaged using fluorescence and polarized light microscopy to visualize the vasculature and collagen, respectively. The vasculature within a 450 μm-thick region containing the LC - identified from the collagen, was segmented, skeletonized, and meshed for simulations. Using Monte Carlo sampling, 200 vascular network models were generated with varying vessel diameter, neural tissue oxygen consumption rate, inflow hematocrit, and blood pressures (arteriole, venule, anterior boundary, and posterior boundary). Factors were varied over ranges of baseline ±20% with uniform probability. For each model we first obtained the blood flow, and from this the neural tissue oxygen concentration. ANOVA was used to identify the factors with the strongest influence on the minimum (10th percentile) oxygen concentration in the LC. The three most influential factors were, in ranked order, vessel diameter, neural tissue oxygen consumption rate, and arteriole pressure. There was a strong interaction between vessel diameter and arteriole pressure whereby the impact of one factor was larger when the other factor was small. Our results show that, for the eye analyzed, conditions that reduce vessel diameter, such as vessel compression due to elevated intraocular pressure or gaze-induced tissue deformation, may particularly contribute to decreased LC oxygen concentration. More eyes must be analyzed before generalizing.

Association Between Dietary Salt Intake and Open Angle Glaucoma in the Thessaloniki Eye Study

PRCIS

In the Thessaloniki Eye Study (TES) incidence phase population, frequent dietary salt intake was potentially associated with increased risk of open angle glaucoma in antihypertensive users.

PURPOSE

The aim was to examine the association between dietary salt intake and glaucoma by antihypertensive use in the TES population.

MATERIALS AND METHODS

The study population included TES incidence phase participants. Dietary salt intake frequency was assessed by self-report. Outcomes included prevalence of any open angle glaucoma (OAG), primary open angle glaucoma (POAG), and pseudoexfoliation (PEX). Covariates included demographics, cardiovascular disease, migraines, diabetes, steroid use, smoking, history of cataract surgery, central corneal thickness, intraocular pressure, blood pressure, and antihypertensive use. Logistic regression was used to examine associations between frequency of salt intake and glaucoma, controlling for covariates and stratified by antihypertensive use.

RESULTS

The study included 1076 participants 80.5±4.4 years old, of whom 518 were female. There were 89/1076 (8.3%) participants with any OAG, 46/789 (5.8%) with POAG, and 287/1030 (27.9%) with PEX. In participants with antihypertensive use, frequent versus never salt intake was associated with increased risk of any OAG [adjusted odds ratio (aOR)=2.65, 95% confidence interval (CI)=1.12, 6.28; n=784] and POAG (aOR=3.59, 95% CI=1.16, 11.11; n=578) overall, and additionally in participants with diastolic blood pressure <90 mm Hg (aOR=2.42, 95% CI=1.00, 5.84; n=735) for OAG. There were no statistically significant adjusted associations between salt intake and PEX, or in participants without antihypertensive use.

CONCLUSIONS

In TES participants assessed for OAG in the prevalence and incidence phases, frequent salt intake may be associated with increased OAG in those who take antihypertensive medication. Further investigation is needed of salt intake and glaucoma in hypertensive individuals.

Dietary Nitrate Intake Is Associated with Decreased Incidence of Open-Angle Glaucoma: The Rotterdam Study

Previous studies suggest that nitric oxide is involved in the regulation of the intraocular pressure (IOP) and in the pathophysiology of open-angle glaucoma (OAG). However, prospective studies investigating the association between dietary nitrate intake, a source of nitric oxide, and incident (i)OAG risk are limited. We aimed to determine the association between dietary nitrate intake and iOAG, and to evaluate the association between dietary nitrate intake and IOP. From 1991 onwards, participants were followed each five years for iOAG in the Rotterdam Study. A total of 173 participants developed iOAG during follow-up. Cases and controls were matched on age (mean ± standard deviation: 65.7 ± 6.9) and sex (%female: 53.2) in a case:control ratio of 1:5. After adjustment for potential confounders, total dietary nitrate intake was associated with a lower iOAG risk (odds ratio (OR) with corresponding 95% confidence interval (95% CI): 0.95 (0.91-0.98) for each 10 mg/day higher intake). Both nitrate intake from vegetables (OR (95% CI): 0.95 (0.91-0.98) for each 10 mg/day higher intake) and nitrate intake from non-vegetable food sources (OR (95% CI): 0.63 (0.41-0.96) for each 10 mg/day higher intake) were associated with a lower iOAG risk. Dietary nitrate intake was not associated with IOP. In conclusion, dietary nitrate intake was associated with a reduced risk of iOAG. IOP-independent mechanisms may underlie the association with OAG.

The role of optical coherence tomography angiography in moderate and advanced primary open-angle glaucoma

PURPOSE

To evaluate the relationship between structure and function in moderate and advanced primary open-angle glaucoma (POAG) and to determine the accuracy of structure and vasculature for discriminating moderate from advanced POAG.

METHODS

In this cross-sectional study, 25 eyes with moderate and 40 eyes with advanced POAG were enrolled. All eyes underwent measurement of the thickness of circumpapillary retinal nerve fiber layer (cpRNFL) and macular ganglion cell complex (GCC), and optical coherence tomography angiography (OCTA) of the optic nerve head (ONH) and macula. Visual field (VF) was evaluated by Swedish interactive threshold algorithm and 24-2 and 10-2 patterns. The correlation between structure and vasculature and the mean deviation (MD) of the VFs was evaluated by a partial correlation coefficient. The area under the receiver operating characteristic curve (AUC) was applied for assessing the power of variables for discrimination moderate from advanced POAG.

RESULTS

Including all eyes, whole image vessel density (wiVD) of the ONH area, and vessel density (VD) in the inferior quadrant of perifovea were the parameters with significant correlation with the mean deviation (MD) of the VF 24-2 in OCTA of the ONH and macula (r = .649 and .397; p < .05). The greatest AUCs for discriminating moderate and advanced POAG belonged to VD of the inferior hemifield of ONH area (.886; 95% CI (.805, .967)), and VD in the inferior quadrant of perifovea (.833; 95% CI (.736, .930)) without statistically significant difference (.886 Versus .833; p = .601).

CONCLUSION

Among vascular parameters of the ONH area, wiVD had the strongest correlation with the MD of the VF 24-2 while VD of the inferior hemifield of the ONH area had the greatest AUC for discriminating moderate and advanced POAG. Vessel density in the inferior quadrant of perifovea had a significant correlation with the MD of VF 24-2 and also the greatest AUC for discriminating moderate and advanced POAG.

Normal-tension glaucoma: Current concepts and approaches-A review

Normal tension glaucoma (NTG) has remained a challenging disease. We review, from an epidemiological perspective, why we should redefine normality, act earlier at lower pre-treatment intraocular pressure (IOP) level, and the role of ocular perfusion pressures, noting that perfusion is affected by defective vascular bed autoregulation and endothelial dysfunction. The correlation of silent cerebral infarcts (SCI) and NTG may indicate that NTG belongs to a wider spectrum of small vessel diseases (SVD), with its main pathology being also on vascular endothelium. Epidemiological studies also suggested that vascular geometry, such as fractal dimension, may affect perfusion efficiency, occurrence of SCI, SVD and glaucoma. Artificial intelligence with deep learning, may help predicting NTG progression from vascular geometry. Finally, we review latest evidence on the role of minimally-invasive glaucoma surgery, lasers, and newer drugs. We conclude that IOP is not the only modifiable risk factors as, many vascular risk factors are readily modifiable.