Association between normal tension glaucoma and the risk of Alzheimer's disease: a nationwide population-based cohort study in Taiwan

Associations between dementia and exposure to topical glaucoma medications

BACKGROUND

Some studies have suggested that glaucoma may be associated with neurodegeneration and a higher risk of dementia.

OBJECTIVE

To evaluate whether exposure to different categories of topical glaucoma medications is associated with differential dementia risks in people with glaucoma.

METHODS

We used data from Adult Changes in Thought, a population-based, prospective cohort study that follows cognitively normal older adults from Kaiser Permanente Washington (KPWA) until Alzheimer's disease (AD) and related dementia development. We included participants with a diagnosis of glaucoma, KPWA pharmacy records of filling topical glaucoma medication (alpha-adrenergic agonists [AAA], beta-adrenergic antagonists, miotics, carbonic anhydrase inhibitors [CAI], and prostaglandins) and at least 10 years of pharmacy records. Eight-year sliding windows were derived for each medication class by computing days on each medication starting 10 years earlier and excluding the most recent 2 years. Cox regression used all 5 classes of medication simultaneously to predict AD and all-cause dementia.

RESULTS

We included 521 participants (mean age 78 [range 65-96], 62% female) with APOE genotype data. Beta-adrenergic antagonists were the most frequently prescribed (n = 431) followed by prostaglandins (351), AAA (239), CAI (162), and miotics (142). Adjusting for time-varying exposure to other glaucoma medications, APOE, demographics, and smoking, each year of use of alpha-adrenergic agonists in an 8-year window was associated with a higher risk of developing dementia (HR = 1.33, 95% CI = 1.03-1.72).

CONCLUSIONS

Among older adults with treated glaucoma, exposure to alpha-adrenergic agonists appears to be associated with risk for developing all-cause dementia.

Female-Specific Association between the Apolipoprotein E E4 Allele and Age at Diagnosis of Glaucoma in UK Biobank

OBJECTIVE

To explore the impact of the apolipoprotein E (APOE) E4 allele in the gender-specific aging process in glaucoma by illustrating the interaction between risk factors, including the APOE E4 allele, gender, and intraocular pressure (IOP), for age at diagnosis (AAD) of glaucoma.

DESIGN

A cross-sectional study included UK Biobank participants with complete data (2006-2010) for analysis. Data were analyzed in December 2023.

PARTICIPANTS

Two thousand two hundred thirty-six glaucoma patients and 103 232 controls.

METHODS

We evaluated multivariable-adjusted associations of AAD of glaucoma, APOE E4 allele (0: absence; 1: presence), and IOP using linear mixed model (LMM) analyses across groups stratified by AAD of mean age of menopause (50 years) and gender.

MAIN OUTCOMES MEASURES

Age at diagnosis of glaucoma, APOE E4 allele, and IOP.

RESULTS

Patients with glaucoma were older and had a higher percentage of males and a higher mean IOP compared to controls (all P < 0.001). Further stratifying the patients with glaucoma by AAD of 50 and gender, lower IOP (model 1 adjusted by age, βIOP = -0.096 ± 0.041, P = 0.019), and positive APOE E4 allele (model 2 adjusted by age and IOP, βe4 = 1.093 ± 0.488, P = 0.026) were associated with an older AAD in females with an AAD <50 years under univariate LMM. In multivariate LMM adjusted by age (model 3), the effect size of both factors increased in the multivariate model as the beta-value increased (βIOP = -0.111 ± 0.040, P = 0.007; βe4 = 1.235 ± 0.485, P = 0.012) (model 1 vs. model 3: P = 0.011). In females with an AAD ≥50 years, only positive APOE E4 allele (adjusted by age and IOP, βe4 = -1.121 ± 0.412, P = 0.007) was associated with a younger AAD. In males, only higher IOP was associated with an older AAD in those with an AAD ≥50 years (βIOP = 0.088 ± 0.032, P = 0.006).

CONCLUSIONS

Apolipoprotein E E4 allele may initially delay and later accelerate the development of glaucoma in females around the transition period of 50 years, which is the mean age of menopause, and importantly, this is independent of IOP. Understanding the specific transition states and modifiable factors within each age phase is crucial for developing interventions or strategies that promote healthy aging.

FINANCIAL DISCLOSURES

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

The association between antiglaucomatous agents and Alzheimer's disease

OBJECTIVES

To estimate the risk of Alzheimer's disease (AD) associated with long-term use of topical glaucoma medications among middle-aged and older glaucoma patients, and compare the AD risk among various glaucoma subtypes.

METHODS

This nationwide population-based cohort study utilized insurance claims data from Taiwan's National Health Insurance Research Database between 2008 and 2019. Participants were adults aged 45 years or older either with a diagnosis of glaucoma or without. Those with glaucoma must have received single antiglaucomatous medication (including α2-adrenergic agonists, cholinergic agonists, beta-blockers, prostaglandin analogs, and pilocarpine) for over 90 days. Those with pre-existing AD diagnoses prior to the index date were excluded.

RESULTS

A total of 202,000 participants were included in the study, with 101,000 in each group (glaucoma and control groups). Glaucoma patients on topical alpha-2 adrenergic agonist monotherapy exhibited a significantly higher AD risk (aHR 1.15, 95% CI = 1.01-1.31) compared to those on beta-blockers. Glaucoma was further categorized into primary open-angle glaucoma (POAG), normal-tension glaucoma (NTG), primary angle-closure glaucoma (PACG), and unspecified glaucoma. Irrespective of the type of glaucoma, individuals with glaucoma had a significantly higher risk of AD compared to those without glaucoma (POAG: aHR 1.23, 95% CI = 1.08-1.40; NTG: aHR 1.49, 95% CI = 1.19-1.85; PACG: aHR 1.35, 95% CI = 1.19-1.52; unspecified glaucoma: aHR 1.36, 95% CI = 1.23-1.50).

CONCLUSIONS

Topical alpha-2 adrenergic agonists might pose increased AD risk in individuals with glaucoma compared to beta-blockers. Accordingly, their utilization should be undertaken judiciously, especially in middle-aged and older populations. Our findings also indicate glaucoma may increase the risk of AD regardless of glaucoma subtype.

Risk of glaucoma to subsequent dementia or cognitive impairment: a systematic review and meta-analysis

BACKGROUND

Substantial evidence supports that glaucoma and dementia share pathological mechanisms and pathogenic risk factors. However, the association between glaucoma, cognitive decline and dementia has yet to be elucidated.

OBJECTIVE

This study was aimed to assess whether glaucoma increase the risk of dementia or cognitive impairment.

METHODS

PubMed, Cochrane Library, Web of Science, and EMBASE databases for cohort or case-control studies were searched from inception to March 10, 2024. The Newcastle-Ottawa Quality Assessment Scale (NOS) was used to the risk of bias. Heterogeneity was rigorously evaluated using the I2 test, while publication bias was assessed by visual inspection of the funnel plot and by Egger' s regression asymmetry test. Subgroup analyses were applied to determine the sources of heterogeneity.

RESULTS

Twenty-seven studies covering 9,061,675 individuals were included. Pooled analyses indicated that glaucoma increased the risk of all-cause dementia, Alzheimer's disease, vascular dementia, and cognitive impairment. Subgroup analysis showed that the prevalence of dementia was 2.90 (95% CI: 1.45-5.77) in age ≥ 65 years and 2.07 (95% CI: 1.18-3.62) in age<65 years; the incidence rates in female glaucoma patients was 1.46 (95% CI: 1.06-2.00), respectively, which was no statistical significance in male patients. Among glaucoma types, POAG was more likely to develop dementia and cognitive impairment. There were also differences in regional distribution, with the highest prevalence in the Asia region, while glaucoma was not associated with dementia in Europe and North America regions.

CONCLUSION

Glaucoma increased the risk of subsequent cognitive impairment and dementia. The type of glaucoma, gender, age, and region composition of the study population may significantly affect the relationship between glaucoma and dementia.

Olfactory Dysfunction and Glaucoma

BACKGROUND

Olfactory dysfunction is a well-known phenomenon in neurological diseases with anosmia and hyposmia serving as clinical or preclinical indicators of Alzheimer's disease, Parkinson's disease, and other neurodegenerative disorders. Since glaucoma is a neurodegenerative disease of the visual system, it may also entail alterations in olfactory function, warranting investigation into potential sensory interconnections.

METHODS

A review of the current literature of the last 15 years (from 1 April 2008 to 1 April 2023) was conducted by two different authors searching for topics related to olfaction and glaucoma.

RESULTS

three papers met the selection criteria. According to these findings, patients with POAG appear to have worse olfaction than healthy subjects. Furthermore, certain predisposing conditions to glaucoma, such as pseudoexfoliation syndrome and primary vascular dysregulation, could possibly induce olfactory changes that can be measured with the Sniffin Stick test.

CONCLUSIONS

the scientific literature on this topic is very limited, and the pathogenesis of olfactory changes in glaucoma is not clear. However, if the results of these studies are confirmed by further research, olfactory testing may be a non-invasive tool to assist clinicians in the early diagnosis of glaucoma.

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.

Risk of Alzheimer's Disease and Related Dementias in Persons with Glaucoma: A National Cohort Study

PURPOSE

Glaucoma is a heterogeneous group of optic neuropathies that potentially may be associated with other cerebral neurodegenerative processes leading to dementia. However, prior studies have been inconsistent. We examined dementia risks after glaucoma diagnosis in a large population-based cohort.

DESIGN

National matched cohort study.

PARTICIPANTS

A total of 324 730 persons diagnosed with glaucoma during 1995-2017 in Sweden and 3 247 300 age- and sex-matched population-based controls without prior dementia.

METHODS

Cox regression was used to compute hazard ratios (HRs) for Alzheimer's disease (AD), vascular dementia (VaD), and all-cause dementia in persons with glaucoma compared with controls, adjusting for sociodemographic factors and comorbidities.

MAIN OUTCOME MEASURES

Alzheimer's disease, VaD, and all-cause dementia identified from nationwide inpatient and outpatient diagnoses through 2018.

RESULTS

In 16 million person-years of follow-up, 32 339 persons (10%) with glaucoma and 226 896 controls (7%) were diagnosed with dementia. Persons with glaucoma had increased risks for AD (adjusted HR, 1.39; 95% confidence interval [CI], 1.35-1.43), VaD (1.66; 1.61-1.72), and all-cause dementia (1.57; 1.54-1.59). Among glaucoma subtypes, both primary open-angle and normal-tension glaucoma were associated with increased risk for AD (adjusted HR, 1.31; 95% CI, 1.27-1.36; and 1.28; 1.20-1.36, respectively) and VaD (1.61; 1.54-1.68; and 1.39; 1.28-1.50, respectively), whereas primary angle-closure glaucoma was associated with VaD (1.26; 1.02-1.56) but not AD (0.98; 0.82-1.18). These findings were similar in men and women. All risks were highest in persons diagnosed with glaucoma at ages ≥ 70 years and were not elevated for ages < 60 years.

CONCLUSIONS

In this large national cohort, persons with glaucoma had increased risks for AD, VaD, and all-cause dementia, particularly those diagnosed with glaucoma at older ages. Persons with glaucoma may need increased monitoring for dementia to facilitate earlier detection and treatment.

FINANCIAL DISCLOSURE(S)

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

Relative Risks for Dementia among Individuals with Glaucoma: A Meta-Analysis of Observational Cohort Studies

PURPOSE

To investigate the relative risks (RRs) for dementia among individuals with glaucoma.

METHODS

We conducted a search of PubMed, Web of Science, Scopus, and Cochrane databases for observational cohort studies examining the association between glaucoma and dementia until March 2023. Two authors independently screened all titles and abstracts according to predefined inclusion and exclusion criteria. Pooled RR and 95% confidence intervals (CIs) were generated using random-effect models.

RESULTS

The meta-analysis included 18 cohort studies conducted in eight countries and involving 4,975,325 individuals. The pooled RR for the association between glaucoma and all-cause dementia was 1.314 (95% CI, 1.099-1.572; I2 = 95%). The pooled RRs for the associations of open-angle glaucoma with Alzheimer dementia and Parkinson disease were 1.287 (95% CI, 1.007-1.646; I2 = 96%) and 1.233 (95% CI, 0.677-2.243; I2 = 73%), respectively. The pooled RRs for the associations of angle-closure glaucoma with all-cause dementia and Alzheimer dementia were 0.978 (95% CI, 0.750-1.277; I2 = 17%) and 0.838 (95% CI, 0.421-1.669; I2 = 16%), respectively. No evidence of publication bias was detected in the Begg-Mazumdar adjusted rank correlation test (p = 0.47).

CONCLUSIONS

Based on current observational cohort studies, there is evidence supporting that glaucoma is a risk factor for dementia in the adult population.

Frequency of coexistent eye diseases and cognitive impairment or dementia: a systematic review and meta-analysis

OBJECTIVE

We aim to quantify the co-existence of age-related macular degeneration (AMD), glaucoma, or diabetic retinopathy (DR) and cognitive impairment or dementia.

METHOD

MEDLINE, EMBASE, PsycINFO and CINAHL were searched (to June 2020). Observational studies reporting incidence or prevalence of AMD, glaucoma, or DR in people with cognitive impairment or dementia, and of cognitive impairment or dementia among people with AMD, glaucoma, or DR were included.

RESULTS

Fifty-six studies (57 reports) were included but marked by heterogeneities in the diagnostic criteria or definitions of the diseases, study design, and case mix. Few studies reported on the incidence. Evidence was sparse but consistent in individuals with mild cognitive impairment where 7.7% glaucoma prevalence was observed. Prevalence of AMD and DR among people with cognitive impairment ranged from 3.9% to 9.4% and from 11.4% to 70.1%, respectively. Prevalence of AMD and glaucoma among people with dementia ranged from 1.4 to 53% and from 0.2% to 25.9%, respectively. Prevalence of DR among people with dementia was 11%. Prevalence of cognitive impairment in people with AMD, glaucoma, and DR ranged from 8.4% to 52.4%, 12.3% to 90.2%, and 3.9% to 77.8%, respectively, and prevalence of dementia in people with AMD, glaucoma and DR ranged from 9.9% to 62.6%, 2.5% to 3.3% and was 12.5%, respectively.

CONCLUSIONS

Frequency of comorbid eye disease and cognitive impairment or dementia varied considerably. While more population-based estimations of the co-existence are needed, interdisciplinary collaboration might be helpful in the management of these conditions to meet healthcare needs of an ageing population.

TRIAL REGISTRATION

PROSPERO registration: CRD42020189484.

The Association Between Eye Disease and Incidence of Dementia: Systematic Review and Meta-Analysis

OBJECTIVES

To better demonstrate the relationship between common eye diseases and the risk of dementia, we conducted a systematic review and meta-analysis of cohort studies to investigate the relationship between common eye diseases and dementia.

DESIGN

Systematic review and meta-analysis.

SETTING AND PARTICIPANTS

Patients with common eye diseases.

METHODS

We conducted a systematic search of articles published up to August 25, 2022, of online databases including PubMed, EMBASE, and Web of Science. We included cohort studies that evaluated the association of glaucoma, age-related macular degeneration (AMD), diabetic retinopathy (DR), and cataracts with all-cause dementia, Alzheimer's disease (AD), and vascular dementia (VaD). Relative risks (RRs) and 95% CIs were pooled using random effects model, and heterogeneity was assessed by the I2 statistic. Subgroup analysis and sensitivity analysis were also performed.

RESULTS

In total, 25 studies were included in the meta-analysis, with a total of 11,410,709 participants. Pooled estimates suggested an increased risk of all-cause dementia associated with AMD (RR, 1.29; 95% CI, 1.13-1.48), glaucoma (RR, 1.16; 95% CI, 1.03-1.32), DR (RR, 1.40; 95% CI, 1.21-1.63), and cataract (RR,1.23; 95% CI, 1.09-1.40); an increased risk of AD associated with AMD (RR, 1.27; 95% CI, 1.06-1.52), glaucoma (RR, 1.18; 95% CI, 1.02-1.38), DR (RR, 1.21; 95% CI, 1.04-1.41), and cataracts (RR,1.22; 95% CI, 1.07-1.38). No association was observed between incident VaD and any eye diseases. The results of subgroup analyses were consistent with those in meta-analysis of DR and risk of all-cause dementia. Meta-regressions suggested geographic regions as potential sources of heterogeneity for the association between AMD and all-cause dementia, AMD and AD, glaucoma and dementia, glaucoma, and AD, respectively.

CONCLUSIONS AND IMPLICATIONS

AMD, glaucoma, DR, and cataract may be associated with an increased risk of all-cause dementia and AD, but not VaD. However, the results should be interpreted cautiously because of the high heterogeneity and unstable findings in some subgroup analyses.

No Strong Association between the Apolipoprotein E E4 Allele and Glaucoma: A Multicohort Study

Purpose

To elucidate a potential association between the apolipoprotein E (APOE) E4 allele and glaucoma prevalence in large cohorts.

Design

A cross-sectional analysis of baseline and prospectively collected cohort data.

Participants

UK Biobank (UKBB) participants of genetically determined European ancestry (n = 438 711). Replication analyses were performed using clinical and genotyping data collected from European participants recruited to the Canadian Longitudinal Study of Aging (CLSA; n = 18 199), the Australian and New Zealand Registry of Advanced Glaucoma (ANZRAG; n = 1970), and the Blue Mountains Eye Study (BMES; n = 2440).

Methods

Apolipoprotein E alleles and genotypes were determined, and their distributions were compared on the basis of glaucoma status. Similar analyses were performed using positive control outcomes associated with the APOE E4 allele (death, dementia, age-related macular degeneration) and negative control outcomes not associated with the APOE E4 allele (cataract, diabetic eye disease). Outcome phenotypes were also correlated with Alzheimer's dementia (AD), a clinical outcome highly associated with the APOE E4 allele.

Main Outcome Measures

Results of APOE E4 genotype-phenotype comparisons were reported as odds ratios (ORs) with 95% confidence intervals (CIs). Replication analyses investigated APOE E4 associations in 2 replication cohorts (CLSA and ANZRAG/BMES).

Results

The APOE E4 allele was inversely associated with glaucoma (OR, 0.96; 95% CI, 0.93-0.99; P = 0.016) and both negative controls (cataract: OR, 0.98; 95% CI, 0.96-0.99; P = 0.015; diabetic eye disease: OR, 0.92; 95% CI, 0.87-0.97; P = 0.003) in the UKBB cohort. A paradoxical positive association was observed between AD and both glaucoma (OR, 1.30; 95% CI, 1.08-1.54; P < 0.01) and cataract (OR, 1.15; 1.04-1.28; P = 0.018). No association between the APOE E4 allele and glaucoma was observed in either replication cohort (CLSA: OR, 1.03; 95% CI, 0.89-1.19; P = 0.66; ANZRAG/BMES: OR, 0.97; 95% CI, 0.84-1.12; P = 0.65).

Conclusions

A small negative association observed between APOE E4 and glaucoma within the UKBB was not evident in either replication cohort and may represent an artifact of glaucoma underdiagnosis in APOE E4 carriers.

Financial Disclosures

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

Pharmaceutical Approaches to Normal Tension Glaucoma

Normal tension glaucoma (NTG) is defined as a subtype of primary open-angle glaucoma (POAG) in which the intraocular pressure (IOP) values are constantly within the statistically normal range without treatment and represents approximately the 30-40% of all glaucomatous cases. The pathophysiology of this condition is multifactorial and is still not completely well known. Several theories have been proposed to explain the onset and progression of this disease, which can be divided into IOP-dependent and IOP-independent factors, suggesting different therapeutic strategies. The current literature strongly supports the fundamental role of IOP in NTG. The gold standard treatment for NTG tends to be based on the lowering IOP even if "statistically normal". Numerous studies have shown, however, that the IOP reduction alone is not enough to slow down or stop the disease progression in all cases, suggesting that other IOP-independent risk factors may contribute to the NTG pathogenesis. In addition to IOP-lowering strategies, several different therapeutic approaches for NTG have been proposed, based on vaso-active, antioxidant, anti-inflammatory and/or neuroprotective substances. To date, unfortunately, there are no standardized or proven treatment alternatives for NTG when compared to traditional IOP reduction treatment regimes. The efficacy of the IOP-independent strategies in decreasing the risk or treating NTG still remains inconclusive. The aim of this review is to highlight strategies reported in the current literature to treat NTG. The paper also describes the challenges in finding appropriate and pertinent treatments for this potentially vision-threatening disease. Further comprehension of NTG pathophysiology can help clinicians determine when to use IOP-lowering treatments alone and when to consider additional or alternatively individualized therapies focused on particular risk factors, on a case-by-case basis.

Could Young Cerebrospinal Fluid Combat Glaucoma? Comment on Lee et al. Association between Optic Nerve Sheath Diameter and Lamina Cribrosa Morphology in Normal-Tension Glaucoma. J. Clin. Med. 2023, 12, 360

I enjoyed reading the article by Lee et al. [...].

Identifying and addressing common contributors to nonadherence with ophthalmic medical therapy

PURPOSE OF REVIEW

To discuss common reasons for nonadherence and review existing and emerging options to reduce nonadherence with ocular medical therapy and optimize therapeutic outcomes.

RECENT FINDINGS

Nonadherence can arise from patient-related issues (e.g. physical, cognitive) and healthcare-related issues (e.g. cost, access to care). Multiple strategies have been developed and evaluated to overcome these barriers to adherence. Identifying nonadherence and its cause(s) facilitates the development of strategies to overcome it.

SUMMARY

Many common causes of nonadherence can be mitigated through a variety of strategies presented.

Associations of ophthalmic and systemic conditions with incident dementia in the UK Biobank

AIMS

To examine independent and interactive associations of ophthalmic and systemic conditions with incident dementia.

METHODS

Our analysis included 12 364 adults aged 55-73 years from the UK Biobank cohort. Participants were assessed between 2006 and 2010 at baseline and were followed up until the early of 2021. Incident dementia was ascertained using hospital inpatient, death records and self-reported data.

RESULTS

Over 1 263 513 person-years of follow-up, 2304 cases of incident dementia were documented. The multivariable-adjusted HRs (95% CI) for dementia associated with age-related macular degeneration (AMD), cataract, diabetes-related eye disease (DRED) and glaucoma at baseline were 1.26 (1.05 to 1.52), 1.11 (1.00 to 1.24), 1.61 (1.30 to 2.00) and (1.07 (0.92 to 1.25), respectively. Diabetes, heart disease, stroke and depression at baseline were all associated with an increased risk of dementia. Of the combination of AMD and a systemic condition, AMD-diabetes was associated with the highest risk for incident dementia (HR (95% CI): 2.73 (1.79 to 4.17)). Individuals with cataract and a systemic condition were 1.19-2.29 times more likely to develop dementia compared with those without cataract and systemic conditions. The corresponding number for DRED and a systemic condition was 1.50-3.24. Diabetes, hypertension, heart disease, depression and stroke newly identified during follow-up mediated the association between cataract and incident dementia as well as the association between DRED and incident dementia.

CONCLUSIONS

AMD, cataract and DRED but not glaucoma are associated with an increased risk of dementia. Individuals with both ophthalmic and systemic conditions are at higher risk of dementia compared with those with an ophthalmic or systemic condition only.

Normal-Tension Glaucoma: A Glymphopathy?

Glaucoma is one of the main causes of irreversible blindness in the world. The most common form, primary open-angle glaucoma, is an optic neuropathy that is characterized by a progressive loss of retinal ganglion cells and their axons, leading to structural changes in the optic nerve head and associated visual field defects. Elevated intraocular pressure remains the most important modifiable risk factor for primary open-angle glaucoma. However, a significant proportion of patients develop glaucomatous damage in the absence of increased intraocular pressure, a condition known as normal-tension glaucoma (NTG). The pathophysiology underlying NTG remains unclear. Several studies have revealed that vascular and cerebrospinal fluid (CSF) factors may play significant roles in the development of NTG. Vascular failure caused by functional or structural abnormalities, and compartmentation of the optic nerve subarachnoid space with disturbed CSF dynamics have been shown to be associated with NTG. In the present article, based on the concept of the glymphatic system and observations in patients with NTG, we hypothesize that failure of fluid transport via the glymphatic pathway in the optic nerve may be involved in the pathogenesis of some if not many cases of NTG. According to this hypothesis, vascular and CSF factors may share reduced glymphatic transport and perivascular waste clearance in the optic nerve as a final common pathway leading to the development of NTG. In addition, we speculate that some cases of NTG may reflect glymphatic dysfunction in natural brain aging and central nervous system diseases, such as Alzheimer's disease. Clearly, further studies are needed to gain additional insight into the relative contribution of these factors and conditions to reduced glymphatic transport in the optic nerve.

Associations between Visual Acuity and Cognitive Decline in Older Adulthood: A 9-Year Longitudinal Study

OBJECTIVE

Emerging evidence suggests low vision may be a modifiable risk factor for cognitive decline. We examined effects of baseline visual acuity (VA) on level of, and change in, cognitive test performance over 9 years.

METHOD

A population-based sample of 1,621 participants (average age 77 years) completed a comprehensive neuropsychological evaluation and VA testing at baseline and reassessed at nine subsequent annual visits. Linear regression modeled the association between baseline VA and concurrent cognitive test performance. Joint modeling of a longitudinal sub-model and a survival sub-model to adjust for attrition were used to examine associations between baseline VA and repeated cognitive test performance over time.

RESULTS

Better baseline VA was associated cross-sectionally with younger age, male sex, greater than high school education, and higher baseline neuropsychological test scores on both vision-dependent (B coefficient range -0.163 to -0.375, p = .006 to <.001) and vision-independent tests (-0.187 to -0.215, p = .003 to .002). In longitudinal modeling, better baseline VA was associated with slower decline in vision-dependent tests (B coefficient range -0.092 to 0.111, p = .005 to <.001) and vision-independent tests (-0.107 to 0.067, p = .007 to <.001).

CONCLUSIONS

Higher VA is associated with higher concurrent cognitive abilities and slower rates of decline over 9 years in both vision-dependent and vision-independent tests of memory, language, and executive functioning. Findings are consistent with emerging literature supporting vision impairment in aging as a potentially modifiable risk factor for cognitive decline. Clinicians should encourage patient utilization of vision assessment and correction with the added aim of protecting cognition.

cGMP Signaling in the Neurovascular Unit-Implications for Retinal Ganglion Cell Survival in Glaucoma

Glaucoma is a progressive age-related disease of the visual system and the leading cause of irreversible blindness worldwide. Currently, intraocular pressure (IOP) is the only modifiable risk factor for the disease, but even as IOP is lowered, the pathology of the disease often progresses. Hence, effective clinical targets for the treatment of glaucoma remain elusive. Glaucoma shares comorbidities with a multitude of vascular diseases, and evidence in humans and animal models demonstrates an association between vascular dysfunction of the retina and glaucoma pathology. Integral to the survival of retinal ganglion cells (RGCs) is functional neurovascular coupling (NVC), providing RGCs with metabolic support in response to neuronal activity. NVC is mediated by cells of the neurovascular unit (NVU), which include vascular cells, glial cells, and neurons. Nitric oxide-cyclic guanosine monophosphate (NO-cGMP) signaling is a prime mediator of NVC between endothelial cells and neurons, but emerging evidence suggests that cGMP signaling is also important in the physiology of other cells of the NVU. NO-cGMP signaling has been implicated in glaucomatous neurodegeneration in humans and mice. In this review, we explore the role of cGMP signaling in the different cell types of the NVU and investigate the potential links between cGMP signaling, breakdown of neurovascular function, and glaucoma pathology.

The APOE E4 Allele Is Associated with Faster Rates of Neuroretinal Thinning in a Prospective Cohort Study of Suspect and Early Glaucoma

Purpose

Design

Participants

Methods

Main Outcome Measures

Results

Conclusions

Fine Particulate Matter Exposure Levels in Patients with Normal-Tension Glaucoma and Primary Open-Angle Glaucoma: A Population-Based Study from Taiwan

Patients with NTG or POAG with more than one outpatient or discharge diagnosis from the ophthalmology department were included in the study. These data were merged with the PM2.5 data from the Air Quality Monitoring Network for analysis. This was a case−control study, with 1006 participants in the NTG group and 2533 in the POAG group. To investigate fine particulate matter (PM2.5) exposure levels in patients with normal-tension glaucoma (NTG) and primary open-angle glaucoma (POAG), patient data were obtained from Taiwan’s Longitudinal Health Insurance Database 2000 for the 2008 to 2013 period. We used a multivariate logic regression model to assess the risk for each participant. The PM2.5 exposure levels were divided into four groups: <25th percentile (Q1), <617 μg/mm3; 25th to 50th percentile (Q2), 617 to 1297 μg/mm3; 50th to 75th percentile (Q3), 1297 to 2113 μg/mm3; and >75th percentile (Q4), >2113 μg/mm3. The results are expressed in terms of odds ratio (OR) and 95% CI. A multiple logistic regression was used to compare the results of the NTG group with those of the POAG group. Compared with the PM2.5 Q1 level, the OR of the PM2.5 Q2 level was 1.009 (95% CI 0.812−1.254), the PM2.5 Q3 level was 1.241 (95% CI 1.241−1.537, p < 0.05), and the PM2.5 Q4 level was 1.246 (95% CI 1.008−1.539, p < 0.05). Our research reveals that compared with POAG, the risk of developing NTG is more closely related with PM2.5 exposure, and PM2.5 has a concentration−dose effect. It is hoped that in the future, in the clinical judgment of NTG and POAG, the level of PM2.5 in the environment can be taken as a risk factor.

Imaging biomarkers for Alzheimer's disease and glaucoma: Current and future practices

Glaucoma is a leading cause of blindness worldwide. Although intraocular pressure is the main risk factor for glaucoma, several intraocular pressure independent factors have been associated with the risk of developing the disease and its progression. The diagnosis of glaucoma relies on clinical features of the optic nerve, visual field test, and optical coherence tomography. However, the multidisciplinary aspect of the disease suggests that other biomarkers may be useful for the diagnosis, thus underling the importance of novel imaging techniques supporting clinicians. This review analyzes the common pathogenic mechanisms between glaucoma and Alzheimer's disease and the possible novel approaches for diagnosis and follow up.

Multiple Systemic Vascular Risk Factors Are Associated With Low-Tension Glaucoma

PRCIS

Multiple systemic vascular-associated conditions including systemic hypertension and hypotension, diabetes mellitus, migraine headache, peripheral vascular disease, Raynaud syndrome, and anemia were associated with low-tension glaucoma.

PURPOSE

The purpose of this study was to identify systemic risk factors associated with low-tension glaucoma.

PATIENTS AND METHODS

A retrospective case-control study design was employed to identify patients seen at the Mayo Clinic Department of Ophthalmology between 2005 and 2015 with low-tension glaucoma and an age-matched and sex-matched control group, each containing 277 patients.

RESULTS

The low-tension glaucoma group had more myopic refractive errors (-1.6 vs. -1.0 D, P<0.001), lower intraocular pressure (14.2 vs. 15.2 mm Hg, P<0.001), and a higher cup-to-disc ratio (0.7 vs. 0.3, P<0.001). The low-tension glaucoma group was significantly less likely to be obese (body mass index >30, P=0.03). This group had a significantly higher prevalence of systemic hypertension [odds ratio (OR): 1.64, P=0.004], diabetes mellitus (OR: 3.01, P<0.001), peripheral vascular disease (OR: 2.61, P=0.009), migraine headache (OR: 2.12, P=0.02), anemia (OR: 2.18, P=0.003), systemic hypotension (OR: 4.43, P<0.001), Raynaud syndrome (OR: 3.09, P=0.05), and angiotensin-converting enzyme inhibitor (OR: 1.64, P=0.01) or calcium channel blocker use (OR: 1.98, P=0.004). After adjusting for systemic hypertension, calcium channel blocker use remained significant (OR: 1.70, P=0.03). No significant difference was found between groups with respect to hyperlipidemia, obstructive sleep apnea, coronary artery disease, carotid stenosis, stroke, or statin, angiotensin-converting enzyme inhibitor, angiotensin receptor blocker, beta-blocker, or metformin use.

CONCLUSIONS

Multiple vascular-associated conditions were associated with low-tension glaucoma including systemic hypertension, diabetes mellitus, peripheral vascular disease, migraine headache, Raynaud syndrome, anemia, systemic hypotension, and calcium channel blocker use. This study strengthens the evidence for the vascular hypothesis of low-tension glaucoma.

Girl Power in Glaucoma: The Role of Estrogen in Primary Open Angle Glaucoma

Estrogen is essential in maintaining various physiological features in women, and a decline in estrogen levels are known to give rise to numerous unfortunate symptoms associated with menopause. To alleviate these symptoms hormone replacement therapy with estrogen is often used, and has been shown to be fruitful in improving quality of life in women suffering from postmenopausal discomforts. An often forgotten condition associated with menopause is the optic nerve disorder, glaucoma. Thus, estrogen may also have an impact in maintaining the retinal ganglion cells (RGCs), which make up the optic nerve, thereby preventing glaucomatous neurodegeneration. This review aims to provide an overview of possible associations of estrogen and the glaucoma subtype, primary open-angle glaucoma (POAG), by evaluating the current literature through a PubMed-based literature search. Multiple in vitro and in vivo studies of RGC protection, as well as clinical and epidemiological data concerning the well-defined retinal neurodegenerative disorder POAG have been reviewed. Over all, deficiencies in retinal estrogen may potentially instigate RGC loss, visual disability, and eventual blindness. Estrogen replacement therapy may therefore be a beneficial future treatment. However, more studies are needed to confirm the relevance of estrogen in glaucoma prevention.

Therapeutic and preventive eff ect of physical exercises in primary open-angle glaucoma

The review assesses physical exercises as an additional non-pharmacological mean of combating the progression of primary open-angle glaucoma. The ophthalmic hypotensive effect is determined by the type of exercise, its duration and intensity. Moderate aerobic activity is preferred. Among dynamic exercises, jogging has the greatest hypotensive effect. Upper body isometric resistance training provides a more lasting decrease in ophthalmotonus. The decrease in intraocular pressure (IOP) in patients with glaucoma is several times more pronounced in comparison with healthy people and occurs regardless of the nature of the local drug antihypertensive therapy. After the termination of classes IOP returns to the previous level on average within a month. An increase in ocular perfusion pressure associated with physical activity dictates the appropriateness of physical exercise for patients with pseudo-normal pressure glaucoma. The combination of hypotensive, vascular, neuroprotective effects of physical activity with a high level of physical fi tness does not exclude a decrease in the risk of development and progression of primary open-angle glaucoma. The development of indications for the use of physical activity by patients with advanced glaucoma, including those who have undergone hypotensive surgery, remains relevant. The type, intensity, dosage and mode of performing the recommended physical exercises require an individual choice.

Comparison of Medical Comorbidity between Patients with Normal-Tension Glaucoma and Primary Open-Angle Glaucoma: A Population-Based Study in Taiwan

The objective was to investigate different comorbidities developed in normal-tension glaucoma (NTG) and primary open-angle glaucoma (POAG) patients. This was a case-control study, with 1489 people in the NTG group and 5120 people in the POAG group. Patient data were obtained from the Longitudinal Health Insurance Database 2010 (LHID2010) of Taiwan for the 2008-2013 period. The chi-square test was used to compare categorical variables, such as gender, income and urbanisation level, between NTG and POAG patients, and the two-tailed t test was used to compare continuity between the two groups. We use a multivariate logic regression model to assess the risk of each participant. The results are expressed in terms of odds ratio (OR) and 95% confidence intervals (CI). Patients with NTG had significantly higher proportions of hypotension (adjusted OR, 1.984; 95% CI, 1.128-3.490), sleep disturbances (adjusted OR, 1.323; 95% CI, 1.146-1.528), peptic ulcers (adjusted OR, 1.383; 95% CI, 1.188-1.609) and allergic rhinitis (adjusted OR, 1.484; 95% CI, 1.290-1.707) than those with POAG. Conversely, arterial hypertension (adjusted OR, 0.767; 95% CI, 0.660-0.893), diabetes (adjusted OR, 0.850; 95% CI, 0.728-0.993) and atopic dermatitis (adjusted OR, 0.869; 95% CI, 0.763-0.990) had a lower risk in the NTG group than in the POAG group. We found that comorbidities such a hypotension, sleep disturbances and peptic ulcer and allergic rhinitis are more highly associated to NTG than POAG.

Association between glaucoma surgery and all-cause and cause-specific mortality among elderly patients with glaucoma: a nationwide population-based cohort study

This population-based, retrospective cohort study aimed to evaluate the association between glaucoma surgery and all-cause and cause-specific mortality among Korean elderly patients with glaucoma. A total of 16210 elderly patients (aged ≥ 60 years) diagnosed with glaucoma between 2003 and 2012 were included, and their insurance data were analyzed. The participants were categorized into a glaucoma surgery cohort (n = 487), which included individuals who had diagnostic codes for open angle glaucoma (OAG) or angle closure glaucoma (ACG) and codes for glaucoma surgery, and a glaucoma diagnosis cohort (n = 15,723), which included patients who had codes for OAG and ACG but not for glaucoma surgery. Sociodemographic factors, Charlson Comorbidity Index score, and ocular comorbidities were included as covariates. Cox regression models were used to assess the association between glaucoma surgery and mortality. The incidence of all-cause mortality was 34.76/1,000 person-years and 27.88/1,000 person-years in the glaucoma surgery and diagnosis groups, respectively. The adjusted hazard ratio (HR) for all-cause mortality associated with glaucoma surgery was 1.31 (95% confidence interval [CI], 1.05–1.62, P = 0.014). The adjusted HR for mortality due to a neurologic cause was significant (HR = 2.66, 95% CI 1.18–6.00, P = 0.018). The adjusted HRs for mortality due to cancer (HR = 2.03, 95% CI 1.07–3.83, P = 0.029) and accident or trauma (HR = 4.00, 95% CI 1.55–10.34, P = 0.004) associated with glaucoma surgery for ACG were significant as well. Glaucoma surgery was associated with an increase of mortality in elderly patients with glaucoma. In particular, the risk of mortality associated with glaucoma surgery due to neurologic causes was significant.

Visual Impairment, Eye Diseases, and Dementia Risk: A Systematic Review and Meta-Analysis

BACKGROUND

Visual impairment and eye diseases have been associated with dementia, though with mixed findings and often in cross-sectional studies.

OBJECTIVE

To identify prospective studies investigating associations between visual impairment or common eye diseases and risk of all-cause dementia or key dementia subtypes.

METHODS

We searched Medline, PsycINFO, and Embase from inception to January 2020. We also conducted backward and forward citation searches of included studies and set up alerts to identify studies published after the search date. Random-effects meta-analysis was used to combine adjusted estimates across studies.

RESULTS

Thirty studies met our eligibility criteria. For visual impairment, pooled estimates indicated an increased risk of all-cause dementia (37,705 participants, 3,415 cases, risk ratio [RR] = 1.38, 95%confidence interval [CI]: 1.19-1.59, I2 = 28.6%). Pooled estimates also suggested an increased dementia risk associated with cataract (6,659 participants, 1,312 cases, hazard ratio [HR] = 1.17, 95%CI 1.00-1.38, I2 = 0.0%) and diabetic retinopathy (43,658 participants, 7,060 cases, HR = 1.34, 95%CI 1.11-1.61, I2 = 63.9%), respectively. There was no evidence of an association between glaucoma (175,357 participants, 44,144 cases, HR = 0.97, 95%CI 0.90-1.04, I2 = 51.5%) or age-related macular degeneration (7,800,692 participants, >  2,559 cases, HR = 1.15, 95%CI 0.88-1.50, I2 = 91.0%) and risk of dementia, respectively.

CONCLUSION

As visual impairment, cataract, and diabetic retinopathy are associated with an increased likelihood of developing dementia, early diagnosis may help identify those at risk of dementia. Given most causes of visual impairment are treatable or preventable, the potential for dementia prevention warrants further investigation.

Normal-tension glaucoma is associated with cognitive impairment

Background/aims

Recent research suggests an association between normal-tension glaucoma (NTG) and dementia. This study investigated whether cognitive impairment is more strongly associated with NTG than high tension glaucoma (HTG) using cognitive screening within an Australiasian Glaucoma Disease Registry.

Methods

The authors completed a case–control cross-sectional cognitive screening involving 290 age-matched and sex-matched NTG participants and HTG controls aged ≥65 randomly sampled from the Australian and New Zealand Registry of Advanced Glaucoma. Cognitive screening was performed using the Telephone Version of the Montreal Cognitive Assessment (T-MoCA). The T-MoCA omits points requiring visual interpretation, accounting for confounding factors related to vision loss in visually impaired participants. Cognitive impairment was defined by a T-MoCA score of <11/22. Cognition was compared between NTG and HTG participants using predetermined thresholds and absolute screening scores.

Results

A total of 290 participants completed cognitive assessment. There were no differences in NTG (n=144) and HTG (n=146) cohort demographics or ocular parameters at baseline. Cognitive impairment was more prevalent in the NTG cohort than the HTG cohort (OR=2.2; 95% CI 1.1 to 6.7, p=0.030). Though a linear trend was also observed between lower absolute T-MoCA scores in the NTG cohort when compared with the HTG cohort, this association was not statistically significant (p=0.108).

Conclusion

This study demonstrated an association between NTG status and poor cognition, supporting the hypothesis that there exists a disease association and shared pathoaetiological features between NTG and dementia.

Decreased Retinal Vascular Density in Alzheimer's Disease (AD) and Mild Cognitive Impairment (MCI): An Optical Coherence Tomography Angiography (OCTA) Study

BACKGROUND

To explore the retinal vascular density changes in Alzheimer's disease (AD) and mild cognitive impairment (MCI) patients using optical coherence tomography angiography (OCTA).

METHODS

We recruit 62 AD patients, 47 MCI patients, and 49 cognitively healthy controls (HC) in this study. All participants in the study received a comprehensive ophthalmological and neurological evaluation, including global cognitive screening, as well as the Mini-Mental State Examination (MMSE), and completed the following eye examinations: visual acuity (VA), intraocular pressure (IOP), examination with slit-lamp, fundus photography (Version 1.5.0.0, NIDEK CO, LTD) and Optical coherence tomography imaging (software ReVue version 2017.1.0.155, Optovue Inc., Fremont, CA, United States). The visual rating scales for atrophy and white matter lesion in MRI was evaluated for all the patients with AD and MCI.

RESULTS

In the AD patient group, the superficial vascular density in the superior, inferior and whole retina was 44.64 ± 3.34, 44.65 ± 3.55, and 44.66 ± 3.36, respectively. These values were 44.24 ± 3.15, 43.72 ± 3.16, and 44 ± 3.07, respectively, in the MCI patient group. After multivariate analysis of the generalized linear model, adjustments for the confounding factors of sex, age, hypertension, diabetes and the quality index of OCTA image, the superficial vascular density in the AD and MCI patient groups was significantly lower than that in the HC group (P < 0.05): 46.94 ± 2.04, 46.67 ± 2.26, and 46.82 ± 2.08, respectively. No difference in the area of the FAZ among the three groups was observed (AD group: 0.34 ± 0.11 mm2; MCI group: 0.36 ± 0.12 mm2; control group: 0.33 ± 0.12 mm2, p > 0.05). The ganglion cell complex (GCC) thickness, inner parafovea thickness, and peripapillary retinal nerve fiber layer (p-RNFL) thickness were associated with the superficial vascular density. We found no significant correlation between the global cognition (MMSE scores) or between the Fazekas score and retinal OCT angiogram flow density.

CONCLUSION

The superficial vascular density in the AD and MCI patient groups was significantly lower than that in the HC group. Our findings suggest the retinal microvascular dysfunction occurred in MCI and AD.

The Association between Vision Impairment and Incidence of Dementia and Cognitive Impairment: A Systematic Review and Meta-analysis

TOPIC

The magnitude and direction of the association between vision impairment and incident dementia and cognitive impairment in prospective cohort studies was estimated by systematic review and meta-analysis. The global burden of dementia associated with vision impairment then was estimated.

CLINICAL RELEVANCE

Because a predominant proportion of vision impairment is preventable or treatable, investigating its association with dementia may help to identify an important modifiable factor for the prevention of dementia.

METHODS

A literature search was conducted using PubMed, Embase, Web of Science, and Google Scholar on September 15, 2020. Relative risks (RRs) were pooled using random-effects models and stratified analyses for subgroups representing different study characteristics. Publication bias was evaluated with funnel plots and the Egger test. The global burden of dementia associated with vision impairment was estimated based on the Global Burden of Disease Study data on the prevalence of dementia and vision impairment.

RESULTS

In the meta-analysis of 14 prospective cohort studies with 6 204 827 participants and 171 888 dementia patients, the pooled RR associated with vision impairment was 1.47 (95% confidence interval [CI], 1.36-1.60). In the meta-analysis of 12 prospective cohort studies with 45 313 participants and 13 350 patients with cognitive impairment, the pooled RR was 1.35 (95% CI, 1.28-1.41). Stratified analyses showed that the associations of vision impairment with incident dementia and cognitive impairment were similar across methods of vision assessment, length of follow-up, and study quality. The global number of people with dementia associated with moderate or severe vision impairment in 2016 was 2.1 million (80% uncertainty interval, 1.0-3.3 million), which accounted for 4.7% (95% CI, 2.3%-7.5%) of the global burden of dementia. Economic inequality was significant for the burden of dementia associated with vision impairment.

DISCUSSION

The overall quality of the body evidence was low because of the observational design of the studies included in the analysis. Vision impairment is associated with an increased risk of both dementia and cognitive impairment in older adults. Screening and treating vision impairment, especially in low- and middle-income countries, may help to alleviate the global burden of dementia.

Association between open-angle glaucoma and Alzheimer's disease in Sweden: a long-term population-based follow-up study

BACKGROUND

Open-angle glaucoma (OAG) and Alzheimer's disease (AD) are two age-related neurodegenerative diseases of significant public health importance. Epidemiological studies have indicated that there might be an association between the disorders.

METHODS

Predictors of AD, including mixed and unspecified dementia, were analysed in a cohort of 712 residents aged 65-74 years, examined in a population survey in the rural district of Tierp, Sweden, from 1984 to 1986. To expand the sample size, 821 people were recruited by means of glaucoma case records established at the Eye Department in Tierp from 1978 to 2007. In this way, the cohort comprised 1,533 people, representing more than 21,000 person-years at risk. Medical records were reviewed to identify subjects diagnosed with dementia. Those with a follow-up duration shorter than 2 years were excluded.

RESULTS

By the conclusion of the study, in August 2020, 307 subjects had received a diagnosis of AD, including mixed and unspecified dementia. Of these cases, 55 were affected with definite OAG at baseline. Higher age and ischemic heart disease were the only predictors of AD identified. In multivariate analysis, adjusting for age, participation in the population survey and competing events, no association was found between OAG and AD (hazard ratio 1.08; 95% confidence interval: 0.80-1.47).

CONCLUSION

In this long-term follow-up study of subjects aged 65-74 years old in Sweden, OAG was not associated with AD.

Neurodegeneration in Alzheimer's disease and glaucoma: overlaps and missing links

The eye is said to be the window into the brain. Alzheimer’s disease (AD) and glaucoma both being diseases of the elderly, have several epidemiological and histological overlaps in pathogenesis. Both these diseases are neurodegenerative conditions. Over the years, a consensus has developed that both may be two ends of a singular spectrum of diseases. Epidemiological studies have shown that more Alzheimer’s patients may be suffering from glaucoma than general healthy population. Retinal ganglion cell damage is a characteristic of both diseases, along with discovery of amyloid-β and tau protein deposition in the retina and aqueous humor of eye. The latter two proteins are known to be pathognomonic of AD. Other pathways such as the insulin receptor pathway also seem to be affected in both diseases similarly. In spite of these overlaps, there are few missing links which still need more evidence, namely, intraocular pressure mechanisms, cerebrospinal fluid pressure and trans-lamina cribrosa pressure gradients, vascular autoregulation factors, etc. Several factors point towards a common pathogenesis at some level for both diseases and prospective studies are necessary to study the natural course of both diseases.

Association between glaucoma and the risk of Alzheimer's disease: A systematic review of observational studies

To address inconsistency as well as investigate the relationship between glaucoma and the risk of Alzheimer's disease (AD). We systematically conducted this meta-analysis based on observational studies published up to 15 January 2018, identified from PubMed and Web of Science. Two team members independently extracted the data and assessed the quality of each included study. Summary relative risk (RR) and 95% confidence intervals (CIs) were calculated using a random-effects model. Eight observational studies with 6870 AD cases were included. The majority of these studies (n = 6) were graded as low risk according to the Newcastle-Ottawa Quality Assessment Scale. Individuals diagnosed with glaucoma, compared to those who were not, had an increased risk of AD (RR = 1.52; 95% CI: 1.41-1.63; I²  = 97%, p < 0.001). A significant finding was also observed for primary open-angle glaucoma (RR = 1.52; 95% CI: 1.41-1.63; I²  = 97%, p < 0.001). However, when stratified by study design, only the case-control studies (RR = 1.08; 95% CI: 0.89-1.31; I²  = 37.3%, p = 0.207) yielded significant results, while the cohort studies did not (RR = 1.08; 95% CI: 0.89-1.31; I²  = 97.7%, p < 0.001). Of note, our meta-regression analysis suggested that study design might be a source of heterogeneity (p = 0.009). Additionally, a significantly positive association was observed when the analyses were restricted to Asia (RR = 2.03; 95% CI: 1.02-4.07). There was no significant publication bias in these analyses. Recent evidence suggests that glaucoma may increase the risk of AD. Additional cohort studies are needed to confirm these findings and to have improved knowledge on the true nature of this association.