Resting intraocular pressure of steel factory workers is related to their physical fitness

Modeling complex age-related eye disease

Modeling complex eye diseases like age-related macular degeneration (AMD) and glaucoma poses significant challenges, since these conditions depend highly on age-related changes that occur over several decades, with many contributing factors remaining unknown. Although both diseases exhibit a relatively high heritability of >50%, a large proportion of individuals carrying AMD- or glaucoma-associated genetic risk variants will never develop these diseases. Furthermore, several environmental and lifestyle factors contribute to and modulate the pathogenesis and progression of AMD and glaucoma. Several strategies replicate the impact of genetic risk variants, pathobiological pathways and environmental and lifestyle factors in AMD and glaucoma in mice and other species. In this review we will primarily discuss the most commonly available mouse models, which have and will likely continue to improve our understanding of the pathobiology of age-related eye diseases. Uncertainties persist whether small animal models can truly recapitulate disease progression and vision loss in patients, raising doubts regarding their usefulness when testing novel gene or drug therapies. We will elaborate on concerns that relate to shorter lifespan, body size and allometries, lack of macula and a true lamina cribrosa, as well as absence and sequence disparities of certain genes and differences in their chromosomal location in mice. Since biological, rather than chronological, age likely predisposes an organism for both glaucoma and AMD, more rapidly aging organisms like small rodents may open up possibilities that will make research of these diseases more timely and financially feasible. On the other hand, due to the above-mentioned anatomical and physiological features, as well as pharmacokinetic and -dynamic differences small animal models are not ideal to study the natural progression of vision loss or the efficacy and safety of novel therapies. In this context, we will also discuss the advantages and pitfalls of alternative models that include larger species, such as non-human primates and rabbits, patient-derived retinal organoids, and human organ donor eyes.

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.

Correlating Intraocular Pressure, Blood Pressure, and Heart Rate Changes after Jogging

Purpose

To examine the effects of jogging on intraocular pressure (IOP), blood pressure (BP), and heart rate (HR).

METHODS

Twenty-nine healthy individuals-25 athletes and 4 untrained-were studied. IOP, systolic and diastolic BP, and HR were measured before and just after 20 minutes of jogging (submaximal - 70% - aerobic exercise).

Results

IOP decreased after jogging. Only three individuals had unchanged IOP in one eye and one individual in both eyes. The IOP decrease (1 to 8 mmHg) was statistically significant (p<0.001). BP increased after jogging (systolic: 0 to 60 mmHg, statistically significant changes, p<0.001; diastolic: 0 to 15 mmHg, statistically significant changes, p<0.001). HR increased as well (15 to 80 pulses/min, statistically significant changes, p<0.001). However, there were individuals who presented a significant decrease of IOP and a mild BP rise and vice versa, and also individuals with mild IOP decrease and significant HR change and vice versa. The statistical analysis clearly showed that there are no linear quantitative correlations between BP or HR changes and IOP changes.

CONCLUSIONS

IOP decreases after jogging. Changes in BP and HR values have no linear quantitative correlation with IOP decrease.

Comparison of the influence of aerobic and resistance exercise of the upper and lower limb on intraocular pressure

PURPOSE

To compare the influence of aerobic and resistance exercise on intraocular pressure (IOP).

METHODS

Twenty-one healthy subjects participated. Aerobic exercise was performed using a cycle ergometer, and resistance exercise was performed with a leg curl and a butterfly machine. Intraocular pressure was measured at baseline, during exercise and 10 min after. During resistance exercise, a Valsalva manoeuvre was prevented.

RESULTS

Before aerobic exercise, the mean IOP was 18.8±2.7 mmHg. It was 16.5±2.8 after 10, 17.1±2.6 after 20 and 16.7±3.3 mmHg after 30 min of exercise. After 10 min, the IOP returned to baseline (18.8 ±2.7 mmHg). The mean IOP before resistance exercise with the leg curl machine was 17.0 (15.6-18.4; 65%Wmax ) and 16.8 (15.3-18.3) mmHg; 75%Wmax ) and did not change significantly during the experiment. The mean IOP before resistance exercise with the butterfly machine (65%Wmax ) was 16.4 (15.2-17.6) and increased to 17.2 (16.0-18.4) mmHg (p<0.05). After 10 min of recreation, it recovered to 16.3 (15.0-17.5) mmHg. At 75%Wmax , the mean baseline IOP was 16.3 (15.2-17.4) mmHg, and there were no significant changes.

CONCLUSIONS

Aerobic exercise leads to a significant decrease of IOP. There was no influence of resistance exercise on IOP as long as a Valsalva manoeuvre was prevented.

Occupational lifting tasks and retinal detachment in non-myopics and myopics: extended analysis of a case-control study

Objectives

Lifting heavy weights involves the Valsalva manoeuvre, which leads to intraocular pressure spikes. We used data from a case-control study to further investigate the hypothesis that occupational lifting is a risk factor for retinal detachment.

Methods

The study population included 48 cases (patients operated for retinal detachment) and 84 controls (outpatients attending an eye clinic). The odds ratios (OR) of idiopathic retinal detachment were estimated with a logistic regression model (adjusted for age, sex and body mass index). Three indexes were used to examine exposure to lifting; 1) maximum load lifted, 2) average weekly lifting, 3) lifelong cumulative lifting.

Results

For all indexes, the most exposed subjects showed an increased risk of retinal detachment compared with the unexposed (index 1: OR 3.57, 95% confidence interval [CI] 1.21-10.48; index 2: OR 3.24, 95% CI 1.32-7.97; index 3: OR 2.23, 95% CI 1.27-8.74) and dose-response relationships were apparent.

Conclusion

These results reinforce the hypothesis that heavy occupational lifting may be a relevant risk factor for retinal detachment.

Relationship of incident glaucoma versus physical activity and fitness in male runners

PURPOSE

To assess the dose-response relationship of vigorous physical activity (running distance, km x d(-1)) or cardiorespiratory fitness (meters-per-second pace during a 10-km footrace) to the risk for incident glaucoma.

DESIGN

Prospective epidemiologic cohort study.

METHODS

Participant-reported, physician-diagnosed incident glaucoma was compared with distance run per week and 10-km footrace performance in a cohort of 29,854 male runners without diabetes followed prospectively for 7.7 yr. The survival analyses were adjusted for age, hypertension, current and past cigarette use, and intakes of meat, fish, fruit, and alcohol.

RESULTS

Two hundred incident glaucoma cases were reported during follow-up. The risk for reported glaucoma decreased 37% per meter per second increment in a 10-km race performance (P = 0.005). Relative to the least fit men (i.e., slowest, < or = 3.5 m x s(-1)), the risk for incident-reported glaucoma declined 29% in those who ran 3.6-4.0 m x s(-1) (P = 0.06), 54% for those who ran 4.1-4.5 m x s(-1) (P = 0.001), 51% for those who ran 4.6-5.0 m x s(-1) (P = 0.04), and glaucoma was nonexistent among the 781 men who exceeded 5.0 m x s(-1) (P = 0.03). The risk for incident, reported glaucoma decreased 5% per kilometer per day run at baseline (P = 0.04), which remained significant when adjusted for the 10-km race performance (5% reduction per kilometer per day, P = 0.04), and both body mass index and race performance (P = 0.04). Baseline hypertension was unrelated to the incident glaucoma.

CONCLUSIONS

These data provide preliminary evidence that vigorous physical activity may reduce glaucoma risk, which, in the absence of medical record validation, could represent ocular hypertension in addition to frank glaucoma. Additional follow-up with validation is needed to identify the type of glaucoma affected.

Lifestyle, nutrition, and glaucoma

The only proven strategy to prevent primary open-angle glaucoma (POAG) is the use of ocular hypotensive therapy among people diagnosed with ocular hypertension. In this review, various modifiable lifestyle factors, such as exercise, diet, and cigarette smoking, that may influence intraocular pressure and that have been studied in relation to the risk of developing POAG are discussed. Epidemiologic studies on lifestyle factors are few, and the current evidence suggests that there are no environmental factors that are clearly associated with POAG; however, a few factors merit further study. This review also outlines future directions for research into the primary prevention of POAG.

LONG-TERM EFFECTS OF MILD EXERCISE ON INTRAOCULAR PRESSURE IN ATHLETES AND SEDENTARY SUBJECTS

The long-term effects of acute submaximal exercise on intraocular pressures (IOPs) of right-and left-eyes and recovery times to basement levels of IOP in postexercise periods in sedentary and physically fit subjects were investigated. Twenty-five sedentary and 24 physically fit subjects, ranging in age 17 to 22 years, participated. Intraocular pressures were measured by a pneumotonometer. Measurements were taken in the morning at about nine (at rest) and immediately, 30 min and 2 h after acute submaximal exercise. In sedentary subjects, IOPs of both right- and left-eyes decreased immediate after exercise, but, these decreases in both eyes continued 30 min and 2 h after exercise. In physically fit subjects, IOPs of both right- and left-eyes increased immediate after exercise, but decreased after 30 min exercise compared to basement levels, and this decrease continued 2 h after exercise. Acute submaximal exercise decreased IOPs of right and left eyes over a period 2 h in sedentary and physically fit subjects. IOP reducing after exercise was different between right- and left-eyes in sedentary subjects. These results suggest that exercise can be used in ocular hypertension treatment.

EFFECT OF ACUTE SUBMAXIMAL EXERCISE ON INTRAOCULAR PRESSURE IN ATHLETES AND SEDENTARY SUBJECTS

The existing literature is controversial regarding the relationship between physical fitness and intraocular pressure (IOP). Therefore, the effects of acute submaximal exercise on IOP were compared in athletes and sedentary subjects. Acute exercise increased IOP in male athletes, but had no effect in sedentary men. Also, it decreased IOP in sedentary women, but had no effect in female athletes. Sex and physical fitness both were significant factors influencing the changes in IOP due to exercise. These results suggest that acute dynamic exercise is useful to decrease IOP in sedentary women, but not in male athletes. These results may help glaucoma screeners.

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

Effects of mutations in the beta 2-adrenergic receptor (beta 2AR) gene on intraocular pressure (IOP), in response to acute dynamic exercise, were investigated in 19 healthy males (age 22.6 +/- 2.8 years). Intraocular pressures were measured pre- and post-exercise. Weight, height, body mass index, and maximal oxygen (VO2max) uptake were recorded and subjects were genotyped for Arg16Gly, Gln27Glu and Thr164Ile mutations of the beta 2AR gene. Post-exercise, reductions in mean IOP values were found in 16 subjects with the Gly16Gly and Arg16Gly genotypes, but these values remained low in the eight patients with the Gly16Gly genotype 3 h post-exercise, whereas they returned to baseline within 1 h in the eight subjects with the Arg16Gly genotype. beta 2AR stimulation during exercise could be an important regulator of IOP response and determining beta 2AR polymorphisms may improve understanding of pathogenesis and treatment selection in ophthalmic diseases, e.g. glaucoma.