Circadian Rhythm and Glaucoma: What do We Know?

Epigenetic Activation of Circadian Clock Genes Elicits Inflammation in Experimental Murine Dry Eye

PURPOSE

To explore whether circadian clock genes contribute to elicit inflammation in experimental dry eye (EDE).

METHODS

RNA sequencing analyzed mRNA expression patterns in EDE model. RT-qPCR and/or Western blot determined the expression of inflammatory factors and circadian genes during EDE. MethylTarget™ assays determined the promoter methylation levels of Per genes in vivo. Per2 or Per3 knockdown assessed their effects on inflammatory factors in vitro.

RESULTS

We utilized an intelligently controlled environmental system (ICES) to establish a mouse EDE model. The significant upregulated genes were enriched for circadian rhythms. Therein lied oscillatory and time-dependent upregulation of PER2 and PER3, as well as their promoter hypomethylation during EDE. Silencing PER2 or PER3 significantly decreased inflammatory factor expression and also reversed such increased inflammatory response in azacitidine (AZA) treatment in vitro model.

CONCLUSIONS

Our findings suggest that DNA methylation mediated the upregulation of PER2 and PER3, leading to inflammatory response in EDE.

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.

Challenging the "Topical Medications-First" Approach to Glaucoma: A Treatment Paradigm in Evolution

Topical glaucoma medications are effective and safe, but they have numerous well-documented limitations that diminish their long-term utility and sustainability. These limitations can include high rates of nonadherence (with associated glaucoma progression), concerning side effects, inconsistent circadian intraocular pressure (IOP) control, complex dosing regimens, difficulty with self-administration, costs, and decreased quality of life. Despite these limitations, topical medications traditionally have been first-line in the glaucoma treatment algorithm, as no other minimally invasive treatment alternatives existed. In recent years, however, novel interventional therapies-including sustained-release drug-delivery platforms, selective laser trabeculoplasty, and micro-invasive glaucoma surgery procedures-have made it possible to intervene earlier without relying on topical medications. As a result, the topical medication-first treatment approach is being reevaluated in an overall shift toward earlier more proactive interventions.

Association between lifestyle habits and glaucoma incidence: a retrospective cohort study

BACKGROUND/OBJECTIVES

Although lifestyle habits may represent modifiable risk factors of glaucoma, the association between lifestyle factors and glaucoma is not well understood. The aim of this study was to investigate the association between lifestyle habits and the development of glaucoma.

SUBJECTS/METHODS

Participants who underwent health check-ups from 2005 to 2020 using a large-scale administrative claims database in Japan were included in the study. Cox regression analyses were performed where glaucoma development was regressed on the lifestyle (body mass index, current smoking, frequency and amount of alcohol consumption, eating habits, exercise habits and quality of sleep), age, sex, hypertension, diabetes mellitus and dyslipidaemia.

RESULTS

Among the 3,110,743 eligible individuals, 39,975 developed glaucoma during the mean follow-up of 2058 days. Factors associated with increased risk of glaucoma were overweight/obese (vs. moderate weight: hazard ratio, 1.04 [95% confidence interval, 1.02-1.07]), alcohol consumption of 2.5-4.9 units/day, 5-7.4 units/day, and ≥7.5 units/day (vs. <2.5 units/day: 1.05 [1.02-1.08], 1.05 [1.01-1.08] and 1.06 [1.01-1.12], respectively), skipping breakfast (1.14 [1.10-1.17]), late dinner (1.05 [1.03-1.08]) and daily walking of 1 h (1.14 [1.11-1.16]). Factors associated with decreased risk of glaucoma were daily alcohol consumption (vs. rarely: 0.94 [0.91-0.97]) and regular exercise (0.92 [0.90-0.95]).

CONCLUSIONS

Moderate body mass index, having breakfast, avoiding late dinner, limiting alcohol intake to <2.5 units/day, and regular exercise were associated with a reduced risk of developing glaucoma in the Japanese population. These findings may be useful for promoting glaucoma prophylaxis.

Subjective and Objective Measurement of Sleep Quality and Activity in Glaucoma

PRCIS

Glaucoma patients exhibit worse indices of sleep function by both objective and subjective metrics compared with controls.

PURPOSE

The purpose of this study is to characterize the sleep parameters and physical activity levels of glaucoma patients compared with controls.

PATIENTS AND METHODS

A total of 102 patients with a diagnosis of glaucoma in at least 1 eye and 31 control subjects were enrolled in the study. Participants completed the Pittsburgh Sleep Quality Index (PSQI) during enrollment and then wore wrist actigraphs for 7 consecutive days to characterize circadian rhythm, sleep quality, and physical activity. The primary outcomes of the study were subjective and objective metrics of sleep quality using the PSQI and actigraphy devices, respectively. The secondary outcome was physical activity, measured by the actigraphy device.

RESULTS

From the PSQI survey, glaucoma patients had higher (worse) scores compared with controls for sleep latency, sleep duration, and subjective sleep quality, whereas scores for sleep efficiency were lower (better), suggesting more time spent in bed asleep. By actigraphy, time in bed was significantly higher in glaucoma patients as was time awake after sleep onset. Interdaily stability, quantifying the synchronization to the 24-hour light-dark cycle, was lower in glaucoma patients. There were no other significant differences between glaucoma and control patients with regard to rest-activity rhythms or physical activity metrics. In contrast to the survey data, findings from the actigraphy demonstrated that there were no significant associations between the study group and controls regarding sleep efficiency, onset latency, or total sleep time.

CONCLUSIONS

In this study, patients with glaucoma demonstrated several subjective and objective differences in sleep function when compared with controls, whereas physical activity metrics were similar.

AUTOPHAGY IN THE EYE: FROM PHYSIOLOGY TO PATHOPHYSOLOGY

Autophagy is a catabolic self-degradative pathway that promotes the degradation and recycling of intracellular material through the lysosomal compartment. Although first believed to function in conditions of nutritional stress, autophagy is emerging as a critical cellular pathway, involved in a variety of physiological and pathophysiological processes. Autophagy dysregulation is associated with an increasing number of diseases, including ocular diseases. On one hand, mutations in autophagy-related genes have been linked to cataracts, glaucoma, and corneal dystrophy; on the other hand, alterations in autophagy and lysosomal pathways are a common finding in essentially all diseases of the eye. Moreover, LC3-associated phagocytosis, a form of non-canonical autophagy, is critical in promoting visual cycle function. This review collects the latest understanding of autophagy in the context of the eye. We will review and discuss the respective roles of autophagy in the physiology and/or pathophysiology of each of the ocular tissues, its diurnal/circadian variation, as well as its involvement in diseases of the eye.

Association of Glaucoma with Poor Quality of Sleep in an Ethiopian Glaucoma Population – A Comparative Cross-Sectional Study

Background

Glaucoma is a group of ocular disorders characterized by progressive optic nerve damage resulting in irreversible visual field defects. Poor quality of sleep in glaucoma patients could be explained by the reduction of the light input to the circadian system as a result of damage to photosensitive retinal ganglion cells in the retina. Information is limited on the association of poor quality of sleep with glaucoma in general and the Ethiopian glaucoma population in particular.

Objective

The study aimed to explore the association between poor quality of sleep and glaucoma at a Tertiary Eye Care Center in Ethiopia.

Methods

An institutional-based comparative cross-sectional study was conducted among 200 glaucoma and 201 non-glaucoma participants recruited by systematic random sampling. Each group was administered with a Pittsburgh Sleep Quality Index (PSQI) questionnaire. Stata-14 was employed for data analysis; an independent t-test was used to show the statistical difference in the global mean PSQI score for the two groups. A binary logistic regression model was applied to identify factors associated with poor quality of sleep. Statistical significance was declared at a 95% confidence interval and a p-value of <0.05.

Results

The prevalence of poor quality of sleep was 82.5% among the glaucoma population, which statistically differed (p<0.001) from the non-glaucomatous population (55.7%). Poor quality of sleep in glaucoma was associated with older age (adjusted odds ratio (AOR)=4.4, 95% confidence interval (CI): 1.5–5.4), depression (AOR=2.9, 95% CI: 1.1–7.3), visual impairment (AOR=3.9, 95% CI: 1.3–12.3) and severe glaucoma (AOR=2.5, 95% CI: 1.1–5.9).

Conclusion and Recommendation

Poor quality of sleep was significantly higher in the glaucoma population compared to their non-glaucoma control. It was associated with older age, depression, visual impairment and advanced glaucoma. Incorporating psychiatric counseling into the existing glaucoma follow-up was recommended.

Intrinsically photosensitive retinal ganglion cells in glaucoma

Glaucoma is a group of eye diseases afflicting more than 70 million people worldwide. It is characterized by damage to retinal ganglion cells (RGCs) that ultimately leads to the death of the cells and vision loss. The diversity of RGC types has been appreciated for decades, and studies, including ours, have shown that RGCs degenerate and die in a type-specific manner in rodent models of glaucoma. The type-specific loss of RGCs results in differential damage to visual and non-visual functions. One type of RGC, the intrinsically photosensitive retinal ganglion cell (ipRGC), expressing the photopigment melanopsin, serves a broad array of non-visual responses to light. Since its discovery, six subtypes of ipRGC have been described, each contributing to various image-forming and non-image-forming functions such as circadian photoentrainment, the pupillary light reflex, the photic control of mood and sleep, and visual contrast sensitivity. We recently demonstrated a link between type-specific ipRGC survival and behavioral deficits in a mouse model of chronic ocular hypertension. This review focuses on the type-specific ipRGC degeneration and associated behavioral changes in animal models and glaucoma patients. A better understanding of how glaucomatous insult impacts the ipRGC-based circuits will have broad impacts on improving the treatment of glaucoma-associated non-visual disorders.

Differential effects of experimental glaucoma on intrinsically photosensitive retinal ganglion cells in mice

Glaucoma is a group of eye diseases characterized by retinal ganglion cell (RGC) loss and optic nerve damage. Studies, including this study, support that RGCs degenerate and die in a type-specific manner following the disease insult. Here we specifically examined one RGC type, the intrinsically photosensitive retinal ganglion cell (ipRGC), and its associated functional deficits in a mouse model of experimental glaucoma. We induced chronic ocular hypertension (OHT) by laser photocoagulation and then characterized the survival of ipRGC subtypes. We found that ipRGCs suffer significant loss, similar to the general RGC population, but ipRGC subtypes are differentially affected following chronic OHT. M4 ipRGCs, which are involved in pattern vision, are susceptible to chronic OHT. Correspondingly, mice with chronic OHT experience reduced contrast sensitivity and visual acuity. By comparison, M1 ipRGCs, which project to the suprachiasmatic nuclei to regulate circadian rhythmicity, exhibit almost no cell loss following chronic OHT. Accordingly, we observed that circadian re-entrainment and circadian rhythmicity are largely not disrupted in OHT mice. Our study demonstrates the link between subtype-specific ipRGC survival and behavioral deficits in glaucomatous mice. These findings provide insight into glaucoma-induced visual behavioral deficits and their underlying mechanisms.

Association Between Postillumination Pupil Response and Glaucoma Severity: A Cross-Sectional Analysis of the LIGHT Study

Purpose

This study determines whether the functional and structural severity of glaucoma is associated with intrinsically photosensitive retinal ganglion cell (ipRGC) function.

Methods

This cross-sectional study assessed 148 eyes from 148 patients with glaucoma (mean age 70.5 years). The ipRGC function was assessed by postillumination pupil response (PIPR) using the pupil diameter after exposure to blue and red light. Main outcome measures were as follows: six-second PIPR amplitude, net PIPR, and net PIPR change. Functional and structural glaucoma severities were evaluated using visual field mean deviation (MD) and the circumpapillary retinal nerve fiber layer (RNFL) thickness, respectively.

Results

Multivariable analysis adjusting for age, sex, body mass index, hypertension, diabetes, oral medication use, cataract surgery, axial length, and topical alpha₂-adrenergic receptor agonist use showed that worsening in visual field MD was significantly associated with higher blue six-second PIPR amplitude (regression coefficient per −1 dB worsening, 0.25; 95% confidence intervals [CI], 0.14, 0.37; P < 0.001). The thinner RNFL thickness was significantly associated with higher blue six-second PIPR amplitude, lower Net PIPR change, and lower net PIPR (blue six-second PIPR amplitude: regression coefficient per 10-µm thinning, 1.29; 95% CI, 0.72, 1.87; P < 0.001; net PIPR change: regression coefficient, −0.70; 95% CI, −1.26, −0.14; P = 0.015; net PIPR: regression coefficient, −0.03; 95% CI, −0.05, −0.001; P = 0.044). No significant association was found between glaucoma severity and red six-second PIPR amplitude.

Conclusions

Our findings revealed a significant association between functional and structural glaucoma severity and impaired ipRGC function independent of potential confounders.

Therapeutic Effects of Melatonin on Ocular Diseases: Knowledge Map and Perspective

Melatonin plays a critical role in the pathophysiological process including circadian rhythm, apoptosis, and oxidative stress. It can be synthesized in ocular tissues, and its receptors are also found in the eye, triggering more investigations concentrated on the role of melatonin in the eye. In the past decades, the protective and therapeutic potentials of melatonin for ocular diseases have been widely revealed in animal models. Herein, we construct a knowledge map of melatonin in treating ocular diseases through bibliometric analysis and review its current understanding and clinical evidence. The overall field could be divided into twelve topics through keywords co-occurrence analysis, in which the glaucoma, myopia, and retinal diseases were of greatest research interests according to the keywords burst detection. The existing clinical trials of melatonin in ocular diseases mainly focused on the glaucoma, and more research should be promoted, especially for various diseases and drug administration. We also discuss its bioavailability and further research topics including developing melatonin sensors for personalized medication, acting as stem cell therapy assistant drug, and consuming food-derived melatonin for facilitating its clinical transformation.

Seasonal variation in neurohormones, mood and sleep in patients with primary open angle glaucoma - implications of the ipRGC-system

Primary open angle glaucoma is associated with an increased risk of mood and sleep disorders. These adversities have been suggested to relate to a disrupted function of the intrinsically photosensitive retinal ganglion cells (ipRGCs). The ipRGCs are key components in the nonvisual photoreceptive system that mediates light effects on mood, sleep and circadian rhythm. We assessed the diurnal hormone levels, pupillary responses and mood and sleep under seasons with different photoperiods in 24 patients with glaucoma and 24 age- and sex-matched healthy controls to investigate responses to naturalistic seasonal changes in daylight. The patients had moderate-to-advanced glaucoma with substantial visual field defects and reductions in the ipRGC-mediated pupillary responses (p < .001). In winter, compared with summer, patients with glaucoma had higher daytime melatonin concentration (p < .001) and lower nighttime cortisol (p = .002). In winter, the daytime melatonin level was inversely correlated with the ipRGC-mediated pupillary responses in the control group (p = .04). In the control group, there were no significant changes in hormone levels between seasons or any correlations between neurohormone levels and the ipRGC-mediated responses. The two groups showed a similar response to season with lower depression scores in summer compared with winter. In between-group comparison, the nocturnal melatonin level (area under curve from 20:00 h to 08:00 h) in summer was lower in glaucoma compared with controls (p = .03). In winter, nocturnal cortisol (at 04:00 h) was lower (p = .004) and daytime cortisol (12:00 h and 16:00 h) was higher (p = .007) in glaucoma compared with controls. In conclusion, we found that patients with glaucoma displayed a seasonal variation in diurnal hormone levels that was not present in healthy controls. Such neurohormonal changes may contribute to the increased risk of mood and sleep disorders seen in patients with glaucoma.

Short-term Evaluation of Negative Pressure Applied by the Multi-Pressure Dial System to Lower Nocturnal IOP: A Prospective, Controlled, Intra-subject Study

Introduction

The purpose of this study was to investigate the short-term safety and feasibility of negative pressure application by the Multi-Pressure Dial (MPD) System to lower nocturnal intraocular pressure (IOP) in subjects with open-angle glaucoma (OAG).

Methods

A prospective, controlled, intra-subject study of 22 eyes from 11 subjects at a single site was performed. All subjects had a history of OAG and were currently using a topical prostaglandin. For each subject, the eye with the highest IOP in the supine position was selected as the treatment eye (TE) and the contralateral eye served as the control eye (CE). The negative pressure for the TE was set to 60% of the baseline IOP value with no negative pressure in the CE. IOP measurements were collected at three prespecified time points overnight in the supine position with active negative pressure. The primary outcome measure was mean IOP with the application of negative pressure.

Results

At the three overnight time points, the mean (± standard deviation) baseline IOP prior to negative pressure application was 22.2 ± 2.5 mmHg in the TE and 21.8 ± 2.5 mmHg in the CE. With the application of 60% negative pressure to the TE and no active negative pressure to the CE, the mean IOP was 14.2 ± 2.2 and 19.5 ± 2.4 mmHg, respectively. The mean percentage IOP reduction in the TE was 35% (p < 0.001). There were two minor adverse events, both unrelated to device wear, and there were no IOP spikes ≥ 10 mmHg.

Conclusion

The MPD can safely and effectively lower nocturnal IOP in the supine position. The MPD holds promise as a potential new, non-invasive treatment option for the control of nocturnal IOP.

Endocrine Dysfunction in Open Angle Glaucoma

The eye, like all organs, is exposed to the effects of the body's endocrine system. In addition, however, local branches of the endocrine system control important organ-specific functions, such as the production and drainage of aqueous humour. Similarly, the eye as a sensory organ acts back on endocrine controlled functions of the body, for example the day-night rhythm. This article aims to illustrate the physiological and pathological interactions of the eye and the endocrine functions of the body in the context of glaucoma. 1. The renin-angiotensin-aldosterone system, which as a local system is involved in the control of aqueous humour production and outflow. 2. The hormone endothelin, which as a strong vasoconstrictor plays a role in the dysregulated perfusion of the optic nerve and retina, and 3. the disruption of the day-night rhythm in advanced glaucoma, which is thought to be caused by damage to light-sensitive ganglion cells.