Blood Pressure and Heart Rate Variability in Primary Open-Angle Glaucoma and Normal Tension Glaucoma

The Relevance of Arterial Blood Pressure in the Management of Glaucoma Progression: A Systematic Review

BACKGROUND

Glaucoma is one of the leading causes of global blindness and is expected to co-occur more frequently with vascular morbidities in the upcoming years, as both are aging-related diseases. Yet, the pathogenesis of glaucoma is not entirely elucidated and the interplay between intraocular pressure, arterial blood pressure (BP) and ocular perfusion pressure is poorly understood.

OBJECTIVES

This systematic review aims to provide clinicians with the latest literature regarding the management of arterial BP in glaucoma patients.

METHODS

A systematic search was performed in Medline, Embase, Web of Science and Cochrane Library. Articles written in English assessing the influence of arterial BP and systemic antihypertensive treatment of glaucoma and its management were eligible for inclusion. Additional studies were identified by revising references included in selected articles.

RESULTS

80 Articles were included in this systemic review. A bimodal relation between BP and glaucoma progression was found. Both high and low BP increase the risk of glaucoma. Glaucoma progression was, possibly via ocular perfusion pressure variation, strongly associated with nocturnal dipping and high variability in the BP over 24 h.

CONCLUSIONS

We concluded that systemic BP level associates with glaucomatous damage and provided recommendations for the management and study of arterial BP in glaucoma. Prospective clinical trials are needed to further support these recommendations.

Visit-to-visit variability in blood pressure and the risk of open-angle glaucoma in individuals without systemic hypertension: a nationwide population-based cohort study

Purpose

We aimed to evaluate the effect of visit-to-visit variability in blood pressure (BP) on the risk of open-angle glaucoma (OAG) in individuals without systemic hypertension using a population-based retrospective cohort study design.

Methods

The Korean National Health Insurance Service-National Health Screening Cohort database, which collected data of 209,226 individuals between 2002 and 2015, was used to analyze the data of 140,910 eligible participants. The mean follow-up duration was 8.3 years. Visit-to-visit BP variability was assessed using standard deviation (SD), coefficient of variation (CV), and variability independent of the mean (VIM). Participants were categorized into four groups according to BP variability quartiles. We verified the effect of BP variability by comparing participants of the first to third quartiles of BP variability groups with those belonging to the fourth quartile group. A Cox proportional hazards model was used to determine the hazard ratio (HR) of BP variability in cases of newly diagnosed OAG. Moreover, we conducted subgroup analyses using baseline characteristics.

Results

In the multivariable analyses, BP variability did not significantly increase the risk of OAG development. However, subgroup analyses revealed significant interactions between age and systolic BP variability in the development of OAG (CV: p = 0.008; SD: p = 0.007). For participants aged <60 years, the risk of OAG development significantly increased with high systolic BP variability (CV: HR, 1.18; 95% confidence interval [CI], 1.00-1.39; p = 0.049). We observed a similar trend using the SD and VIM as the parameters for systolic BP variability.

Conclusion

Higher visit-to-visit systolic BP variability was associated with an increased risk of OAG development in participants younger than 60 years of age without systemic hypertension. These results suggest that BP variability can be the considerable factor when assessing the risk of OAG, especially in relatively young people without systemic hypertension.

Association of glaucoma and lifestyle with incident cardiovascular disease: a longitudinal prospective study from UK Biobank

The shared pathophysiological features of the cerebrovascular disease (CVD) and glaucoma suggest an association between the two diseases. Using the prospective UK Biobank cohort, we examined the associations between glaucoma and incident CVD and assessed the extent to which a healthy lifestyle reduced the CVD risk in subjects with glaucoma, using a scoring system consisting of four factors: current smoking, obesity, regular physical activity, and a healthy diet. During a mean follow-up time of 8.9 years, 22,649 (4.9%) incident CVD cases were documented. Multivariable Cox regression analyses revealed that subjects with glaucoma were significantly more likely to exhibit incident CVD (hazard ratio [HR]:1.19, 95% confidence interval [CI] 1.03-1.37; p = 0.016) than controls. In the further subgroup analyses, glaucoma increased incident CVD risk both in the young (40-55 years) and the old (56-70 years) and in both sexes, with higher risk in the young (HR: 1.33, CI 1.02-1.74) and female subjects (HR: 1.32, CI 1.14-1.52). When we analyze the associations between glaucoma and incident CVD by lifestyle factors, the highest absolute risks were observed in individuals with both glaucoma and an unhealthy lifestyle (HR: 2.66, CI 2.22-3.19). In conclusion, glaucoma was an independent risk factor for incident CVD. A healthy lifestyle was associated with a substantially lower risk for CVD incidence among adults with glaucoma.

Ocular and Hemodynamic Factors Contributing to the Central Visual Function in Glaucoma Patients With Myopia

Purpose

The purpose of this study was to investigate the ocular and hemodynamic factors contributing to the central visual function in glaucoma patients with myopia.

Methods

This study was a prospective observational study, which included 236 eyes of 140 patients with normal-tension glaucoma (NTG), which includes 114 eyes with mild myopia (axial length ≥24 and <26 mm) and 122 eyes with moderate-to-severe myopia (axial length ≥26 mm). Ocular characteristics were axial length and posterior pole profiles, including peripapillary atrophy (PPA) to disc area ratio, disc tilt ratio, disc torsion, and disc-foveal angle. Hemodynamic factors included standard deviation of the mean of qualified normal-to-normal intervals (SDNN) of a heart rate variability (HRV) test and vessel density (VD) parameters from optical coherence tomography angiography (OCTA). The root mean square error was estimated as a measure of the VD fluctuation. Association between ocular characteristics and VD parameters of the OCTA with the central sensitivity of the 10-degree visual field or the presence of central scotoma were analyzed.

Results

Deep layer VD of the peripapillary and macular areas showed significant differences between mild and moderate-to-severe myopia (P = 0.034 and P = 0.045, respectively). Structural parameters, especially PPA to disc area ratio, had significant correlation with peripapillary VD parameters in myopic eyes. Lower SDNN value (ß = 0.924, P = 0.011), lower deep VD of the macular area (ß = 0.845, P = 0.001), and greater fluctuation of deep VD in the peripapillary area (ß = 1.517, P = 0.005) were associated with the presence of central scotoma in patients with glaucoma with myopia in multivariate logistic regression analysis.

Conclusions

The structural changes by myopia, especially in the peripapillary region, affected VD parameters in myopic eyes. Lower deep VD and greater VD fluctuation in the peripapillary region showed association with central scotoma in patients with glaucoma with myopia, suggesting both structural and vascular changes by myopia may be related to central visual function in glaucoma patients with myopia.

Role of ocular blood flow in normal tension glaucoma

Background

Normal tension glaucoma (NTG) is a multifactorial disease in the pathogenesis of which intraocular pressure (IOP)-independent factors play a key role.

Main text

There is considerable evidence that impairment of the ocular blood flow (OBF) is involved both in the onset and progression of this disease. With the development of the hypothesis of OBF in NTG, various imaging techniques have been developed to evaluate the OBF and blood vessels. Moreover, vascular dysregulation, which is a main factor in Flammer syndrome, was frequently observed in NTG patients. Disturbed OBF leads to increased oxidative stress, which plays an important role in the pathogenesis of glaucomatous optic neuropathy. These results suggested that IOP-independent management may provide alternative treatment options for NTG patients.

Conclusions

In this review, we mainly focus on the mechanisms of the abnormal OBF in NTG.

Angiotensin II related glial cell activation and necroptosis of retinal ganglion cells after systemic hypotension in glaucoma

The purpose of this study was to design an animal model mimicking glaucoma with hemodynamic instability and to identify involvement of angiotensin II (AngII) and associated changes of the retina. Systemic hypotension was induced in Sprague–Dawley rats by oral hydrochlorothiazide administration. Rats were sacrificed at 4, 8, and 12-week time points. AngII and receptor levels were examined in the serum and retina. To examine the relationship between glia activation and associated RGC death, biochemical analysis of GFAP, Iba-1, and necroptosis associated factors such as TNFα, receptor-interacting protein (RIP) 1, 3, and inactive caspase 8 were explored. To investigate the difference in RGC death mechanism, JNK inhibitor or RIP3 inhibitor were given intraperitoneally to rats with ocular hypertension and systemic hypotension both to identify the pathway mainly involved. AngII and receptors were increased in the serum and retina of systemic hypotensive rat. At 4, 8, and 12 weeks after hypotension induction, glial activation was increased as indicated by GFAP and Iba-1 staining. TNFα, RIP3 were elevated. and downregulation of inactive caspase 8 was apparent in the retina of hypotensive rat. Electron microscopy revealed that necroptosis of RGC was gradually increased after systemic hypotension. Following intraperitoneal JNK inhibitor or RIP3 inhibitor administration, RGC loss was attenuated in systemic hypotensive rats but not in ocular hypertensive rats. In conclusion, AngII is involved in glial activation and associated RGC necroptosis following systemic hypotension. This pathway represents a novel and distinct cell death mechanism when compared to that involved in elevated intraocular pressure.

Normal-tension glaucomatous optic neuropathy is related to blood pressure variability in the Maracaibo Aging Study

Hypoperfusion of the optic nerve might be involved in the pathogenesis of normal-tension glaucomatous optic neuropathy (GON). Mean arterial pressure (MAP) drives ocular perfusion, but no previous studies have addressed the risk of GON in relation to blood pressure (BP) variability, independent of BP level. In a cross-sectional study, 93 residents of Maracaibo, Venezuela, underwent optical coherence tomography, visual field assessments and 24-h ambulatory BP monitoring between 2011 and 2016. We investigated the association of normal-tension GON with or without visual field defects with reading-to reading variability of 24-h MAP, as captured by variability independent of the MAP level (VIM_map). Odds ratios (ORs) were adjusted for 24-h MAP level and for a propensity score of up to five risk factors. Among the 93 participants (87.1% women; mean age, 61.9 years), 26 had open-angle normal-tension GON at both eyes; 14 had visual field defects; and 19 did not have visual field defects. The OR ratios for normal-tension GON, expressed per 1-SD increment in VIM_map (2 mm Hg), were 2.17 (95% confidence interval, 1.33-3.53) unadjusted; 2.20 (1.35-3.61) adjusted for 24-h MAP level only; 1.93 (1.10-3.41) with additional adjustment for age, educational attainment, high-density lipoprotein (HDL) cholesterol and office hypertension; and 1.95 (1.10-3.45) in models including intraocular pressure. We confirmed our a priori hypothesis that BP variability, most likely operating via hypoperfusion of the optic nerve, is associated with normal-tension GON. 24-H ambulatory BP monitoring might therefore help stratify the risk of normal-tension GON.

Association of ocular blood flow and contrast sensitivity in normal tension glaucoma

Purpose

To investigate the relationship of ocular blood flow (via arteriovenous passage time, AVP) and contrast sensitivity (CS) in healthy as well as normal tension glaucoma (NTG) subjects.

Design

Mono-center comparative prospective trial

Methods

Twenty-five NTG patients without medication and 25 healthy test participants were recruited. AVP as a measure of retinal blood flow was recorded via fluorescein angiography after CS measurement using digital image analysis. Association of AVP and CS at 4 spatial frequencies (3, 6, 12, and 18 cycles per degree, cpd) was explored with correlation analysis.

Results

Significant differences regarding AVP, visual field defect, intraocular pressure, and CS measurement were recorded in-between the control group and NTG patients. In NTG patients, AVP was significantly correlated to CS at all investigated cpd (3 cpd: r =  − 0.432, p< 0.03; 6 cpd: r =  − 0.629, p< 0.0005; 12 cpd: r =  − 0.535, p< 0.005; and 18 cpd: r =  − 0.58, p< 0.001), whereas no significant correlations were found in the control group. Visual acuity was significantly correlated to CS at 6, 12, and 18 cpd in NTG patients (r =  − 0.68, p< 0.002; r =  − 0.54, p< .02, and r =  − 0.88, p< 0.0001 respectively), however not in healthy control patients. Age, visual field defect MD, and PSD were not significantly correlated to CS in in the NTG group. MD and PSD were significantly correlated to CS at 3 cpd in healthy eyes (r = 0.55, p< 0.02; r =  − 0.47, p< 0.03).

Conclusion

Retinal blood flow alterations show a relationship with contrast sensitivity loss in NTG patients. This might reflect a disease-related link between retinal blood flow and visual function. This association was not recorded in healthy volunteers.

Relationship between peripheral vasospasm and visual field progression rates in patients with normal-tension glaucoma with low-teen intraocular pressure

Purpose

To investigate the association between peripheral vasospasm and the visual field (VF) progression rate in patients with normal-tension glaucoma (NTG) with low-teen intraocular pressure (IOP).

Methods

The finger temperature of 113 NTG patients was measured before and after exposure to ice water using a Temperature gun (cold pressor test). These patients had confirmed VF progression, despite a low-teen IOP during a follow-up period of >5 years. VF progression rates were calculated as the slope of the visual field index (VFI) and mean deviation (MD) over time. Demographic, systemic, and ocular factors and VF progression rates were compared, based on the cold pressor test results. A regression analysis was used to investigate the factors affecting VF progression rates.

Results

Mean age, initial IOP, mean IOP during the follow-up period, and initial VF MD were 57.1 years, 15.8 mmHg, 12.0 mmHg, and -5.2 dB, respectively. When patients were divided into two groups (less vasospasm and more vasospasm) according to changes in temperature after exposure to ice water, the VF progression rate was significantly faster in the group with more vasospasm. In a multiple regression analysis, older age, worse initial VF MD, and greater decrease in finger temperature after ice water exposure were significantly associated with faster VF progression rates.

Conclusion

An excessive drop in finger temperature after exposure to ice water was significantly associated with faster VF progression in patients with low-teen NTG. This suggests that the blood flow in the optic nerve head may also be disturbed by peripheral vasospasm, accelerating glaucomatous damage regardless of IOP.

Effect of depressive symptom and depressive disorder on glaucoma incidence in elderly

Although depression and glaucoma share several common pathophysiology, the risk of glaucoma in patients with depression has not been reported. Thus, we investigated the effect of depressive symptom and depressive disorder on glaucoma incidence. In this nationwide population-based cohort study, all subjects receiving the National Screening Program at the age of 66 during 2009-2014 were included. These subjects were divided into depression group and no depression group based on subjective depressive symptoms and clinically diagnosed depressive disorder and were tracked until 2017 for development of glaucoma. Of the 922,769 subjects included in the study, 191,636 (20.77%) subjects were categorized as depression group. Subjects with depression showed increased hazard of developing glaucoma (adjusted HR = 1.12[95% confidence interval (CI), 1.09-1.15]) than those without depression. The risk of glaucoma increased sequentially from those with no depression to those with subjective depressive symptom (adjusted HR = 1.09[95% CI, 1.06-1.13]), those with clinically diagnosed depressive disorder (adjusted HR = 1.23[95% CI, 1.14-1.32]), and those with both subjective depressive symptom and clinically diagnosed depressive disorder (adjusted HR = 1.36[95% CI, 1.22-1.52]). Our analyses suggest that individuals with depression had a greater risk of developing glaucoma than those without depression. Subjective depressive symptoms and clinically diagnosed depressive disorder independently and synergistically increased the risk of glaucoma incidence.

Association of dipping status of blood pressure, visual field defects, and retinal nerve fiber layer thickness in patients with normotensive glaucoma

The aim of this study was to evaluate the association between dipping status of blood pressure (BP), visual field defects (VFDs), and retinal nerve fiber layer (RNFL) thickness in patients with normotensive glaucoma (NTG). Our University echocardiography, electrocardiogram, 24-hour BP monitor and glaucoma database were reviewed from 2016 to 2018 to identify patients with NTG and hypertension (HTN). These NTG patients were followed for a mean 26.4 ± 13.6 months and were divided into 2 groups according to the absence or presence of VFDs. Among the 110 patients with NTG, 55 (50%) patients had VFDs. There were no differences of baseline characteristics between 2 groups. In univariate analysis, extreme dipper status at night in the 24-hour BP monitoring, HTN, age, diabetes mellitus, and hyperlipidemia were significantly associated with VFDs. In multivariate analysis, extreme dipper status at night in the 24-hour BP monitoring (odds ratio [OR] 4.094; P = .045) and HTN (OR 2.368; P = .048) were independent risk factors for VFDs at 2-year follow-up. Moreover, the RNFL thickness was thinner in NTG patients with VFDs (P < .001). VFDs group had more increased fluctuation of systolic and diastolic BP in 24-hour BP monitoring and that the extreme dipper status at night in the 24-hour BP monitoring and HTN itself were also associated with higher incidence of VFDs and thinning changes of the RNFL in patients with NTG, suggesting that more intensive medical therapy with close clinical follow-up will be required for these patients.

Autonomic Dysfunction and Blood Pressure in Glaucoma Patients: The Lifelines Cohort Study

Purpose

We investigated relationship of glaucoma with measurements related to autonomic dysfunction, including heart rate variability (HRV) and blood pressure (BP).

Methods

Glaucoma was defined using a questionnaire-based algorithm for 86,841 LifeLines Cohort Study participants. Baseline HRV (root mean square of successive differences [RMSSD]) was calculated from resting electrocardiograms; systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP), and pulse pressure (PP) were oscillometric-based measurements. We used a generalized linear mixed model, adjusted for age, age square, sex, body mass index, and familial relationships to assess the relationship of baseline HRV and BP (continuous and quartiles), hypertension, and antihypertensive medication with glaucoma at follow up (median, 3.8 years).

Results

The odds ratio (OR) of glaucoma was 0.95 (95% confidence interval [CI], 0.92-0.99) per unit increase in log-transformed RMSSD (in ms), indicating that autonomous dysfunction (low HRV) is associated with a higher risk of glaucoma. Per 10-mm Hg increase in BP, we found ORs of 1.03 (95% CI, 1.01-1.05; P = 0.015) for SBP, 1.01 (95% CI, 0.97-1.05; P = 0.55) for DBP, 1.03 (95% CI, 1.00-1.06; P = 0.083) for MAP, and 1.04 (95% CI, 1.01-1.07; P = 0.006) for PP. The OR for the lowest versus highest RMSSD quartile was 1.15 (95% CI, 1.05-1.27; P = 0.003). The ORs for the highest versus second quartile were 1.09 (95% CI, 0.99-1.19; P = 0.091) for SBP and 1.13 (95% CI, 1.02-1.24; P = 0.015) for PP. Glaucoma was more common among hypertensives (OR, 1.25; 95% CI, 1.16-1.35; P < 0.001); among those using angiotensin-converting enzyme (ACE) inhibitors (OR, 1.35; 95% CI, 1.18-1.55; P < 0.001); and among those using calcium-channel blockers (OR, 1.19; 95% CI, 1.01-1.40; P = 0.039).

Conclusions

Low HRV, high SBP, high PP, and hypertension were associated with glaucoma. Longitudinal studies may elucidate if autonomic dysregulation and high BP also predict glaucoma incidence.

Microbial dysbiosis and microbiota-gut-retina axis: The lesson from brain neurodegenerative diseases to primary open-angle glaucoma pathogenesis of autoimmunity

In recent years, microbiota-associated neurodegenerative diseases have been exploited and provided new insight into disease pathogenesis. However, primary open-angle glaucoma (POAG), known as a complex neurodegenerative disease resulting from retinal ganglion cell death and optic nerve damage, can cause irreversible blindness and visual field loss. POAG, which shares several similarities with Parkinson's disease (PD) and Alzheimer's disease (AD), has limited studies and slow progression in the understanding of pathogenesis when compared to PD and AD. In this review, we summarized the current knowledge of POAG and commensal microbiota, combined with several lines of evidence in PD and AD to propose a possible hypothesis for POAG pathogenesis: microorganisms cause glaucoma via gut-retina axis, resulting in autoantibodies and autoreactive T cells that lead to autoimmunity. Furthermore, dual-hit hypothesis, an example of a commensal pathogen that causes PD, was partially exported in POAG. Finally, future perspectives are suggested to expand understanding of POAG.