The impact of acute dynamic exercise on intraocular pressure: role of the beta 2-adrenergic receptor polymorphism

Low cardiorespiratory fitness is associated with elevated intraocular pressure among apparently healthy adults

PURPOSE

To evaluate the association of cardiorespiratory fitness with elevated intraocular pressure (IOP) in healthy adults.

METHODS

In this cross-sectional study, we evaluated 17,990 asymptomatic self-referred adults free of diabetes or cardiovascular disease who were screened in a preventive healthcare setting. All subjects underwent measurement of IOP and completed a maximal exercise stress test according to the Bruce protocol. Fitness was categorized into age and sex-specific quintiles according to the treadmill time and dichotomized to low (lowest quintile) and non-low fitness groups. Elevated IOP was defined as ≥ 21 mmHg.

RESULTS

Median age was 45 (IQR 39-52) years and 12,073 (67%) were men. There were 3,351 (19%) subjects in the low fitness group. Median IOP was 14 mmHg (IQR 12-16) with elevated IOP documented in 188 (1%) subjects. Univariate binary logistic regression model demonstrated that compared with non-low fitness group, subjects in the low fitness group were 2.2 times more likely to have elevated IOP (95% CI 1.598-2.95, p<0.001). Multivariate binary logistic regression with adjustment to known cardiovascular risk factors (age, sex, hypertension, smoking, overweight, regular physical activity, low HDL cholesterol, high triglycerides, and fasting glucose levels) successfully demonstrated that lower fitness was independently and significantly associated with a 90% increased likelihood of elevated IOP (95% CI 1.37-2.61, p<0.001). Subgroup analysis revealed that the association was more pronounced among women compared with men (OR 3.8 vs. 1.6, p for interaction = 0.069).

CONCLUSIONS

Low cardiorespiratory fitness is independently associated with increased IOP among apparently healthy adults.

Evaluation of ADRB2 and OATP2A1 genetic polymorphisms in Indian patients with primary open-angle glaucoma

The emergence of adrenergic β2-receptor (ADRB2) blockers has revolutionized glaucoma treatment, while the discovery of prostaglandin analogs has further expanded therapeutic options. Organic anion transporting polypeptide 2A1 (OATP2A1/SLCO2A1) facilitates the corneal transport of topical prostaglandins into anterior segment of eye. Our study aims to elucidate the prevalence of genetic polymorphisms in the ADRB2 and OATP2A1 to address variations in therapeutic responses among glaucoma patients. The study cohort comprised primary open-angle glaucoma patients (POAG, n = 77), compared to non-glaucomatous controls (n = 60) to identify polymorphisms rs1042713 (Arg16Gly, A > G) and rs1042714 (Gln27Glu, C > G) in the ADRB2 gene and rs34550074 (Ala396Thr, A > G) in OATP2A1 gene, using Sanger sequencing. Among the enrolled subjects (n = 137), the POAG group exhibited significantly elevated intraocular pressure ( P  < 0.001) and cup-to-disc ratio ( P  < 0.0001). The GA genotype of rs1042713 ( P  < 0.01) and the GG genotype of rs1042714 ( P  < 0.05) were positively associated with POAG, while rs34550074 ( P  > 0.05) showed no significant correlation with the disease. This study reveals the association of the ADRB2 gene polymorphisms with POAG, whereas OATP2A1 polymorphism did not show significant correlation.

Effects of regular exercise on intraocular pressure

BACKGROUND

Exercise may potentially provide an adjunctive measure to help control intraocular pressure in glaucoma patients. However, currently, there is still no substantial evidence that regular exercise can produce a prolonged effect of intraocular pressure reduction. We aim to determine the effects of regular exercise on intraocular pressure in healthy individuals.

METHODS

We conducted a prospective, interventional study at the University of Malaya Medical Centre. Our subjects consist of 45 healthy participants in the intervention arm, and 38 healthy control participants who were age- and gender-matched. The intervention arm was enrolled into a supervised exercise programme for a 6-week period, where controls were asked to continue their usual daily lifestyle. The intervention consists of three sessions every week, which focused on aerobic exercise and strength training.

RESULTS

Baseline intraocular pressure was measured, and then remeasured again at the end of 6 weeks of exercise conditioning. In the intervention group, there was a reduction of baseline intraocular pressure from pre-intervention mean intraocular pressure of 15.55 ± 2.63 mmHg, down to 13.36 ± 3.16 mmHg at 6 weeks, a statistically significant reduction of -2.18 ± 2.25 mmHg (p < 0.001) post-intervention. On the other hand, the control group recorded a non-statistically significant mean increase of 0.63 ± 2.47 mmHg (p = 0.123) at 6 weeks.

CONCLUSIONS

Our study concluded that regular exercise results in a significant intraocular pressure reduction in healthy individuals.

Aerobic exercise reduces intraocular pressure and expands Schlemm's canal dimensions in healthy and primary open-angle glaucoma eyes

Purpose

Aerobic exercise (AE) has been reported to decrease intraocular pressure (IOP) in healthy subjects and there are concomitant morphological changes in the anterior segment of the eye including the Schlemm's canal (SC). However, its effects on IOP and SC morphology in glaucoma patients had not been studied before. We aim to investigate the effect of AE on the IOP and SC dimension in both healthy and primary open-angle glaucoma (POAG) eyes.

Methods

The area and diameter of SC and IOP were measured in 35 primary open-angle glaucoma (POAG) patients (59 eyes) and 36 healthy subjects (72 eyes) before and after performing moderate intensity of AE by running on a treadmill for 30 min. SC was imaged by swept-source optical coherence tomography (SS-OCT) for evaluation.

Results

In comparison with baseline values, mean IOP decreased significantly following AE in both POAG and healthy eyes (both P < 0.001), in which POAG eyes showed a greater degree of reduction compared to healthy eyes (P = 0.002). In comparison with baseline values, in both POAG and healthy eyes, the average cross-sectional area (POAG: 80.48 +/- 59.54 vs. 99.20 +/- 54.87 pixels; healthy: 151.84 +/- 52.76 vs. 198.23 +/- 53.70 pixels; both P < 0.001) and diameter (POAG: 3.73 +/- 1.69 vs. 4.33 +/- 1.74 pixels; healthy: 5.61 +/- 1.02 vs. 6.47 +/- 1.20 pixels; both P < 0.001) of SC significantly increased after AE. In POAG, both treated and untreated with IOP-lowering medications, a significant reduction in mean IOP and increase in SC dimensions following AE were observed (all P < 0.05), and there were no significant differences of such measurements between the two subgroups (all P > 0.05).

Conclusion

AE-induced reduction in IOP and an increase in SC dimensions in POAG eyes as in healthy eyes. Further studies to evaluate the long-term effect of AE on IOP control and SC morphology in POAG seem warranted.

Long-term regular exercise and intraocular pressure: the Hisayama Study

PURPOSE

To investigate the association between long-term regular exercise (exercise frequency and exercise time) and 5-year changes in intraocular pressure in a general Japanese population.

METHODS

This population-based, cohort study was conducted in 2007. A total of 3119 Japanese community dwellers aged ≥ 40 years underwent eye examinations including intraocular pressure measurement with a noncontact tonometer. Of these, 1871 subjects (801 men and 1070 women) who underwent intraocular pressure measurement in 2012 participated. We assessed the associations of exercise frequency and exercise time with intraocular pressure using a linear regression model, adjusted for age and possible risk factors that can affect intraocular pressure.

RESULTS

The mean 5-year intraocular pressure change ± standard deviation was - 0.84 ± 1.9 mmHg. After adjustment for age, sex, systolic blood pressure, diabetes, total cholesterol, high-density lipoprotein cholesterol, body mass index, waist circumference, smoking habit, alcohol intake, work intensity levels, and intraocular pressure at baseline, we observed that increased exercise frequency (times/week) and increased exercise time (min/week) were both significantly associated with reduced intraocular pressure (p < 0.05 each). In the subgroup analyses based on the presence/absence of possible confounding risk factors, there was no evidence of heterogeneity among all subgroups (p for heterogeneity > 0.2).

CONCLUSIONS

Increased exercise frequency levels and increased exercise time are both independently associated with reduced intraocular pressure levels after adjustment for confounding factors.

Postexercise Recovery of Schlemm's Canal and Intraocular Pressure in Healthy Individuals: An Observational Study Using Swept-Source Optical Coherence Tomography

Purpose

To observe the recovery process of postexercise Schlemm's canal (SC) and intraocular pressure (IOP) in healthy individuals.

Methods

Twenty healthy individuals were recruited. SC and IOP were evaluated before exercise, immediately after exercise, and 15, 30, and 60 minutes after exercise. Superior, inferior, nasal, and temporal SC quadrants were evaluated using swept-source optical coherence tomography (SS-OCT).

Results

Average SC area (3726.81 ± 1167.06 vs. 4660.57 ± 1284.82 µm²) and perimeter (324.11 ± 58.95 vs. 367.19 ± 73.34 µm) increased, and IOP (14.02 ± 2.33 vs. 11.65 ± 1.90 mmHg) decreased significantly during exercise (all p < 0.001). After exercise, both SC and IOP recovered to preexercise values, and the recovery time for postexercise SC dimensions (15 minutes) was shorter than that for postexercise IOP (60 minutes). After adjusting for age, gender, axial length, central corneal thickness, and spherical equivalent, postexercise changes in SC dimensions were not significantly associated with postexercise changes in IOP compared with preexercise values (all p > 0.05). There were no significant differences in the observable SC proportion before and after exercise (all p > 0.05).

Conclusions

The exercise-induced SC expansion and IOP reduction could recover to preexercise values after exercise, and SC recovered to preexercise values ahead of IOP. Moreover, SC might be regulated by the sympathetic nerves and could be an important causative factor of changes in IOP during and after exercise.

Relationship Between Post-Exercise Changes in the Lens and Schlemm's Canal: A Swept-Source Optical Coherence Tomography Study

AIM

To observe post-exercise changes in the lens and Schlemm's canal (SC) in healthy individuals using swept-source optical coherence tomography (SS-OCT).

METHODS

Thirty-five healthy, young individuals were recruited and performed aerobic exercise by jogging for 20 minutes. The SC area, SC perimeter, trabecular meshwork (TM) length, TM thickness, lens vault (LV), and lens thickness (LT) were assessed by SS-OCT before and after exercise.

RESULTS

Following aerobic exercise, SC area (4260.85 ± 1476.02 vs. 5158.24 ± 1527.42 μm², p < 0.001), SC perimeter (349.21 ± 62.22 vs. 391.24 ± 71.77 μm, p < 0.001), TM length (781.16 ± 114.83 vs. 816.46 ± 121.26 μm, p < 0.001), and TM thickness (111.52 ± 19.30 vs. 116.96 ± 17.57 μm, p = 0.004) increased significantly, while LV (-0.134 ± 0.198 vs. -0.195 ± 0.198 mm, p < 0.001) decreased significantly and LT showed no significant post-exercise changes (3.86 ± 0.32 vs. 3.85 ± 0.32 mm, p = 0.801). Moreover, post-exercise changes in SC area were significantly associated with post-exercise changes in LV (β = -6487.83; p = 0.040).

CONCLUSIONS

Aerobic exercise induces both backward axial displacement of the lens and SC expansion. This backward axial displacement of the lens could be an important causative factor of the post-exercise SC expansion via the lens-zonular-ciliotrabecular vector and the connecting fibrils between ciliary body and SC.

Changes in intraocular pressure after exercise test

BACKGROUND

The decrease in intraocular pressure (IOP) within exercise has been recently suggested; however, this change remained ambiguous following exercise test. The present study aimed to assess changes in IOP induced by exercise test in patients who suspected to coronary artery disease (CAD) and indicated for exercise test evaluation.

METHODS

In a cross-sectional study at the cardiovascular research center of Amin Heart Hospital in Isfahan, 101 eyes from 51 consecutive patients suspected to CAD aged 30-70 years referred for exercise testing were evaluated. IOP was measured at the three time points of before exercise test as well as 5 and 20 min after completing exercise test using Schiotz tonometer. All exercise tests were programmed by the treadmill.

RESULTS

The mean IOP in all assessed eyes was 16.12 ± 2.61 mmHg initially that was gradually decreased to 13.79 ± 2.40 mmHg 5 min after the exercise test, but elevated to 15.67 ± 2.26 mmHg 20 min after the test. Assessing IOP following exercise testing showed a significant decrease in IOP in 75 eyes (74.3%), remained unchanged in 19.8% of eyes, and even elevated in 5.9% of eyes. There was a significant direct association between patients' age and IOP changes assessed by the Pearson's correlation test (r = 0.350,P = 0.009). No significant difference was revealed in the trend of the changes in IOP after exercise test between men and women, between left-sided and right-sided eyes as well as between different body mass index subgroups.

CONCLUSION

IOP temporarily reduced after exercise test, but return to baseline value shortly after test. This lowering is more evident in advanced aging.

The short-term effects of exercise on intraocular pressure, choroidal thickness and axial length

Purpose

To explore ocular changes in healthy people after exercise.

Methods

Twenty five volunteers underwent exercise for 15 minutes on a treadmill. Measurements of choroidal thickness, intraocular pressure (IOP), ocular biometry, and blood pressure were taken before and after exercise. Enhanced Depth Imaging optical coherence tomography (EDI-OCT) was used to measure choroidal thickness at the fovea. Intraocular pressure (IOP) was measured by Goldmann applanation tonometry. Ocular biometric measures were collected using A scan ultrasound. Blood pressure was measured concurrently with the acquisition of the scans.

Results

Twenty five volunteers (25 eyes) with a mean age of 25.44±3.25 years were measured. There was a significant increase in systolic and diastolic pressure after exercise (P<0.05). The IOP showed a significant decrease after exercise (P<0.05). However there was no significant difference in the mean choroidal thickness, ocular axial length, anterior chamber depth, lens thickness, or vitreous length before and after exercise measurements (P>0.05).

Conclusion

There was a significant decrease in IOP from exercise without a change in choroidal thickness and ocular biometric measures. IOP and choroidal thickness were not correlated, suggesting that the IOP decrease from exercise is not due to changes in choridal thickness.

Glaucomics: a call for systems diagnostics for 21(st) century ophthalmology and personalized visual health

This article analyzes and theorizes the current knowledge silos at the intersection of omics science, ophthalmology, personalized medicine, and global visual health. Visual disorders represent one of the largest health care expenditures in the United States, costing $139 billion per year. In middle-income and industrialized countries, glaucoma is a World Health Organization priority category eye disease, known for difficulties in its early diagnosis, chronic progressive nature, and large person-to-person differences in drug efficacy and safety. A complex disease, glaucoma is best conceptualized as a syndrome displaying an ostensibly common clinical end-point, but with vastly heterogeneous molecular underpinnings and host-environment interactions. About 12% of all global blindness is attributable to glaucoma. Glaucomics is a term that we coin here so as to introduce omics science and systems diagnostics to ophthalmology, a field that can benefit enormously from personalized medicine, and which has sadly lagged behind in systems diagnostics compared to fields such as oncology. We define glaucomics as the integrated use of multi-omics and systems science approaches towards rational discovery, development, and tandem applications of diagnostics and therapeutics, for glaucoma specifically, and for personalized visual health, more broadly. We propose that glaucoma is one of the neglected lowest hanging fruits and actionable targets for omics and systems diagnostics in 21(st) century ophthalmology for the salient reasons we describe here. Additionally, we offer an analysis on two of the most pertinent neglected tropical diseases (NTDs), trachoma and river blindness, which continue to plague visual health in developing countries. We conclude with a call for research on omics applications in glaucoma and personalized visual health.

Progress toward personalized medicine for glaucoma

How will you respond when a patient asks, "Doctor, what can I do to prevent myself from going blind from glaucoma like mom?". There is optimism that genetic profiling will help target patients to individualized treatments based on validated disease risk alleles, validated pharmacogenetic markers and behavioral modification. Personalized medicine will become a reality through identification of disease and pharmacogenetic markers, followed by careful study of how to employ this information in order to improve treatment outcomes. With advances in genomic technologies, research has shifted from the simple monogenic disease model to a complex multigenic and environmental disease model to answer these questions. Our challenges lie in developing risk models that incorporate gene-gene interactions, gene copy-number variations, environmental interactions, treatment effects and clinical covariates.

Aerobic exercise and intraocular pressure in normotensive and glaucoma patients

BACKGROUND

With the increasing number of people participating in physical aerobic exercise, jogging in particular, we considered that it would be worth knowing if there are should be limits to the exercise with regard to the intraocular pressure (IOP) of the eyes. The purpose of this study is to check IOP in healthy and primary glaucoma patients after aerobic exercise.

METHODS

145 individuals were subdivided into seven groups: normotensives who exercised regularly (Group A); normotensives in whose right eye (RE) timolol maleate 0.5% (Group B), latanoprost 0.005% (Group C), or brimonidine tartrate 0.2% (Group D) was instilled; and primary glaucoma patients under monotherapy with beta-blockers (Group E), prostaglandin analogues (Group F) or combined antiglaucoma treatment (Group G) instilled in both eyes. The IOP of both eyes was measured before and after exercise.

RESULTS

A statistically significant decrease was found in IOP during jogging. The aerobic exercise reduces the IOP in those eyes where a b-blocker, a prostaglandin analogue or an alpha-agonist was previously instilled. The IOP is also decreased in glaucoma patients who are already under antiglaucoma treatment.

CONCLUSION

There is no ocular restriction for simple glaucoma patients in performing aerobic physical activity.

Influencing ocular blood flow in glaucoma patients: the cardiovascular system and healthy lifestyle choices

The cardiovascular system and lifestyle choices play important roles in influencing ocular blood flow regulation in patients with glaucoma. This includes the presence of vascular risk factors, abnormal autoregulatory responses, tissue oxygenation, and mitochondrial oxidative stress. Based on this comprehensive review, novel therapeutic approaches may be considered in selected patients for preventing and (or) delaying the progression of glaucoma.

Pharmacogenetics of ophthalmic topical beta-blockers

Glaucoma is the second leading cause of blindness worldwide. The primary glaucoma risk factor is elevated intraocular pressure. Topical beta-blockers are affordable and widely used to lower intraocular pressure. Genetic variability has been postulated to contribute to interpersonal differences in efficacy and safety of topical beta-blockers. This review summarizes clinically significant polymorphisms that have been identified in the beta-adrenergic receptors (ADRB1, ADRB2 and ADRB3). The implications of polymorphisms in CYP2D6 are also discussed. Although the candidate-gene approach has facilitated significant progress in our understanding of the genetic basis of glaucoma treatment response, most drug responses involve a large number of genes, each containing multiple polymorphisms. Genome-wide association studies may yield a more comprehensive set of polymorphisms associated with glaucoma outcomes. An understanding of the genetic mechanisms associated with variability in individual responses to topical beta-blockers may advance individualized treatment at a lower cost.