Effects of mild, moderate and severe exercise on intraocular pressure of sedentary subjects

Acute Effects of Resistance Exercise on Intraocular Pressure in Healthy Adults: A Systematic Review

ABSTRACT

Hackett, DA, Li, J, Wang, B, Way, KL, Cross, T, and Tran, DL. Acute effects of resistance exercise on intraocular pressure in healthy adults: A systematic review. J Strength Cond Res 38(2): 394-404, 2024-Intraocular pressure (IOP) tends to fluctuate during a resistance exercise (RE). This systematic review examines the acute effects of RE on IOP in healthy adults and factors that influence changes in IOP. Five electronic databases were searched using terms related to RE and IOP. A strict inclusion criterion was applied, which included being 55 years or younger with no medical conditions and RE intensity needing to be quantifiable (e.g., based on a maximal effort). Thirty-four studies met the inclusion criteria for this review. Isometric and isotonic contractions produced similar changes in IOP during RE up to 28.7 mm Hg. Exercises that involved larger muscle mass, such as squats and leg press, were found to produce changes in IOP during exercise ranging from 3.1 to 28.7 mm Hg. Smaller changes in IOP during RE were found for exercises engaging less muscle mass (e.g., handgrip and bicep curls). Intraocular pressure was found to increase during RE when lifting heavier loads and with longer exercise durations (e.g., greater repetitions). The Valsalva maneuver (VM) and breath-hold during RE accentuated the change in IOP, with more extreme changes observed with the VM. However, most studies showed that postexercise IOP returned to baseline after approximately 1 minute of recovery. An acute increase in IOP is observed during RE in healthy adults with fluctuations of varying magnitude. Factors that independently increase IOP during RE include exercises involving larger muscle mass, heavy loads, greater set duration, and when the VM or breath-hold is performed.

Effect of Aerobic Exercise at Different Intensities on Intraocular Pressure in Young Males

PRCIS

High intensity aerobic exercise significantly reduced intraocular pressure in healthy young male adults.

OBJECTIVE

This study sought to determine how aerobic exercise at various intensities affects intraocular pressure (IOP) in young adults.

DESIGN

A repeated measures design was adopted.

PARTICIPANTS

A group of 20 volunteers (mean age: 21.24±1.73 y) took part in this study.

METHODS

IOP was measured with a tonometer (iCare TA01i, Icare Finland, Finland). Subjects completed 4 cycle ergometer sessions. During the first session, power was increased by 60 W every 3 minutes until exhaustion, corresponding to peak power. For the 3 following tests, each lasting 25 minutes, subjects exercised at intensities of 50%, 70%, and 85% of peak power, respectively, and measurements were taken every 5 minutes.

MAIN OUTCOME MEASURES

IOP, as determined using a tonometer, was the primary measure.

RESULTS

There was a significant reduction ( P <0.05) in IOP of both eyes during the 25 minutes high-intensity (85%) exercise test. There were also significant interactions between exercise durations and intensities. During high-intensity exercise, IOP, blood pressure, blood lactate, and the rating of perceived exertion were significantly related ( P <0.01).

CONCLUSIONS

These data show a significant reduction in IOP at high-intensity aerobic exercise, which may have implications for the management of ocular health.

Association of Exercise and Swimming Goggles With Modulation of Cerebro-ocular Hemodynamics and Pressures in a Model of Spaceflight-Associated Neuro-ocular Syndrome

Importance

Astronauts on International Space Station missions demonstrate adverse neuro-ocular changes. Reversing a negative translaminar pressure gradient (TLPG) by modulating cerebral blood flow, decreasing intracranial pressure, or increasing intraocular pressure (IOP) has been proposed as potential intervention for spaceflight-associated neuro-ocular syndrome (SANS).

Objective

To examine whether exercise (resistance, moderate-intensity aerobic, and high-intensity aerobic) or artificially increasing IOP is associated with modulated cerebro-ocular hemodynamic and pressure changes during head-down tilt (HDT), an analogue of spaceflight, in healthy adults.

Design, Setting, and Participants

A single-center investigation was conducted at Johnson Space Center, Houston, Texas, from January 1, 2014, to December 31, 2016, in 20 healthy men.

Exposure

On 3 separate days, participants rested supine, were tilted to -15° HDT, and then completed 1 of 3 experimental exercise conditions (moderate-intensity aerobic, resistance, or high-intensity interval aerobic). A subset of 10 participants wore swimming goggles on all days.

Main Outcomes and Measures

Applanation rebound tonometry was used to noninvasively assess IOP, and compression sonography was used to assess internal jugular venous pressure (IJVP). Estimated TLPG was calculated as the difference between IOP and IJVP. Cerebral inflow and outflow were measured in extracranial arteries using color-coded duplex ultrasonography.

Results

Twenty men participated in the study (mean [SD] age, 36 [9] years). Compared with supine IOP (mean [SD], 19.3 [3.7] mm Hg), IJVP (mean [SD], 21.4 [6.0] mm Hg), and estimated TLPG (mean [SD], -2.1 [7.0] mm Hg), -15° HDT was associated with increased IOP (mean difference, 2.3 mm Hg; 95% CI, 1.4-3.3 mm Hg; P < .001) and IJVP (mean difference, 10.5 mm Hg; 95% CI, 8.9-12.2 mm Hg; P < .001) and with decreased TLPG (mean difference, -8.2 mm Hg; 95% CI, -10.1 to -6.3 mm Hg; P < .001). Exercise (regardless of modality) at -15° HDT was associated with decreased IOP (mean difference, -1.6 mm Hg; 95% CI, -2.6 to -0.6 mm Hg; P = .002) and TLPG (mean difference, -3.5 mm Hg; 95% CI, -6.2 to -0.7 mm Hg; P = .01) compared with rest. Both IOP (mean difference, 2.9 mm Hg; 95% CI, 0.7-5.1 mm Hg; P = .01) and TLPG (mean difference, 5.1 mm Hg; 95% CI, 0.8-9.4 mm Hg; P = .02) were higher in participants who wore swimming goggles compared with those not wearing goggles.

Conclusions and Relevance

In this study, exercise was associated with decreased IOP and estimated translaminar pressure gradient in a spaceflight analogue of HDT. The addition of swimming goggles was associated with increased IOP and TLPG in HDT. Further evaluation in spaceflight may be warranted to determine whether modestly increasing IOP is an effective SANS countermeasure.

Exercise-Induced Changes in Ocular Blood Flow Parameters in Primary Open-Angle Glaucoma Patients

PURPOSE

To evaluate exercise-induced changes in ocular blood flow (OBF) parameters in primary open-angle glaucoma (POAG) patients.

METHODS

A prospective observational study was carried out, in which medically treated patients with POAG were enrolled. Following inclusion, all patients performed a 40-min cycloergometry in a standardized fashion. The following parameters were measured and compared immediately before and 1 and 30 min after the exercise: intraocular pressure (IOP; Goldman applanation tonometry), mean arterial pressure (MAP), ocular pulse amplitude (OPA; assessed by dynamic contour tonometry), and ocular perfusion pressure (OPP; 2/3 MAP - IOP). In addition, we investigated possible factors associated with OBF parameter changes immediately after exercise.

RESULTS

A total of 30 eyes (30 patients; mean age was 62.9 ± 1.7 years) were included. Most patients were women (53%), and median visual field mean deviation index was -3.5 dB. Both MAP (mean change, 21%) and IOP (mean change, 17.3%) increased significantly immediately after the workout (p < 0.01), persisting higher than baseline following 30 min (p < 0.01%). Regarding OBF parameters, both OPA (mean change, 58.8%) and OPP (mean change, 21.7%) increased significantly immediately after the workout and persisted higher than baseline 30 min after the workout (p < 0.01). Regression analysis revealed that only age was significantly associated with OPA variation (R2 0.14; p < 0.05). No significant associations were found for OPP (p ≥ 0.19).

CONCLUSION

Aerobic exercise leads to a significant short-time increase in OBF parameters in patients with POAG. Even though IOP seems to present a modest elevation, it is accompanied by a significant increase in MAP, leading to higher OBF measurements. Exercise-induced short-term changes and its possible implications for glaucoma prognosis deserve further investigation.

[Unmet research and developmental needs in ophthalmology : A consensus-based road map of the European Vision Institute for 2019-2025]

PURPOSE

To define unmet needs in ophthalmology which can realistically be addressed in the next years (2019-2025) and to describe potential avenues for research to address these challenges.

METHODS

Outcomes of a consensus process within the European Vision Institute (EVI, Brussels) are outlined. Disease areas which are discussed comprise glaucoma, retinal dystrophies, diabetic retinopathy, dry eye disease, corneal diseases, cataract and refractive surgery.

RESULTS

Unmet needs in the mentioned disease areas are discussed and realistically achievable research projects outlined.

CONCLUSION

Considerable progress can be made in the field of ophthalmology and patient-relevant outcomes in the near future.

Unmet Needs in Ophthalmology: A European Vision Institute-Consensus Roadmap 2019-2025

PURPOSE

To define unmet needs in ophthalmology that can realistically be addressed in the next 5 years (2019-2025) and describe potential avenues for research to address these challenges.

METHODS

Outcomes of a consensus process within the European Vision institute (Brussels) are outlined. Disease areas that are discussed comprise glaucoma, retinal dystrophies, diabetic retinopathy, dry eye disease, corneal diseases, cataract and refractive surgery.

RESULTS

Unmet needs in the mentioned disease areas are discussed and realistically achievable research projects outlined.

CONCLUSIONS

Considerable progress can be made in the ophthalmic field and patient-relevant outcomes in the near future.

The evaluation of intraocular pressure fluctuation in glaucoma subjects during submaximal exercise using an ocular telemetry sensor

Purpose:

To evaluate the effect of acute submaximal exercise on intraocular pressure (IOP) fluctuations in open-angle glaucoma (OAG) subjects using an ocular telemetry sensor (OTS, Sensimed TriggerFish^®).

Methods:

Twelve OAG subjects aged 45–65 years with no medical limitation for exercise were included in this prospective study. A submaximal exercise test was performed using a cycle ergometer for 20 min during which OTS voltages and metabolic parameters were recorded continuously. IOP voltages taken before, during, and after exercise were compared using the Friedman test and correlations with the metabolic parameters were evaluated using the Spearman analysis.

Results:

In two subjects, the OTS stopped functioning after a few hours. Median OTS measurements were 37.60 mVeq 10 min before exercise [interquartile range (IQR) 137.27], 51.75 (IQR 121.2), 62.35 (IQR 123.72), 54.6 (IQR 141.3), and 59.7 mVeq (IQR 196.7) during exercise (4 time points, 5 min apart), and 50.7 (IQR 147.35) and 64.2 mVeq (IQR 103.25) 10 and 30 min after exercise and the change was statistically non-significant (P = 0.66). No correlations were found between OTS and metabolic parameters measured at the same time points (P > 0.05). Nocturnal acrophase pattern was detected in five subjects (50%), diurnal acrophase in two patients, and double-hump in two patients. Median IOP voltages in the morning, afternoon/evening, and night were 335.84, 149.15, and 341.38 mVeq, respectively (P < 0.001).

Conclusion:

Continuous IOP monitoring did not reveal a remarkable voltage change in OAG patients during or immediately after exercise, but nocturnal IOP peaks in half of the patients.

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.

Intraocular pressure and glaucoma: Is physical exercise beneficial or a risk?

Intraocular pressure may become elevated with muscle exertion, changes in body position and increased respiratory volumes, especially when Valsalva manoeuver mechanisms are involved. All of these factors may be present during physical exercise, especially if hydration levels are increased. This review examines the evidence for intraocular pressure changes during and after physical exercise. Intraocular pressure elevation may result in a reduction in ocular perfusion pressure with the associated possibility of mechanical and/or ischaemic damage to the optic nerve head. A key consideration is the possibility that, rather than being beneficial for patients who are susceptible to glaucomatous pathology, any intraocular pressure elevation could be detrimental. Lower intraocular pressure after exercise may result from its elevation causing accelerated aqueous outflow during exercise. Also examined is the possibility that people who have lower frailty are more likely to exercise as well as less likely to have or develop glaucoma. Consequently, lower prevalence of glaucoma would be expected among people who exercise. The evidence base for this topic is deficient and would be greatly improved by the availability of tonometry assessment during dynamic exercise, more studies which control for hydration levels, and methods for assessing the potential general health benefits of exercise against any possibility of exacerbated glaucomatous pathology for individual patients who are susceptible to such changes.

Intraocular pressure is not associated with acute mountain sickness

OBJECTIVE

Acute mountain sickness (AMS) is common at high altitude and may lead to high altitude cerebral edema (HACE) if not properly recognized. Previous studies have suggested that AMS is associated with increases in intracranial pressure (ICP). Increased ICP has been associated with increased intra-ocular pressure (IOP). This study was designed to determine the association between IOP and AMS.

METHODS

Subjects were recruited from a convenience sample of travelers in the Khumbu region of Nepal, elevation 14,410 ft (4392 m). Study participation involved completion of a questionnaire to assess for AMS by the Lake Louise Score (LLS), followed by three IOP measurements in each eye. Investigators were blinded to the LLS. Subjects with a history of ocular surgery were excluded. Three IOP measurements per eye were made using an applanation tonometer (Tono-Pen XL(®), Reichart Technologies) and averaged across both eyes. Multivariable logistic regression analysis was used to estimate the association between IOP and AMS while adjusting for age, ascent or descent, and use of acetazolamide. IOP and blood O2 saturation were compared using a Spearman correlation coefficient.

RESULTS

161 subjects were enrolled with a median age of 36 (IQR: 29-45) years; 60% were male, 75% were ascending, and 64% were taking acetazolamide; additionally, 38%, (95% CI: 31%-47%) were diagnosed with AMS (LLS ≥3). The median IOP was 21 (IQR 18-24) mmHg. The logistic regression model demonstrated no association between IOP and AMS as measured by LLS (odds ratio [OR] 1.0, 95% CI: 0.9-1.1),age (OR 1.0, 95% CI: 0.9-1.0) or with use of acetazolamide (OR 1.4, 95% CI: 0.6-2.6). Ascent (OR 0.4, 95% CI: 0.2-0.9) was negatively associated with IOP but not significantly so. IOP and O2 saturation were not correlated (p=0.93).

CONCLUSIONS

IOP measured at high altitude is not associated with the diagnosis of AMS. Other approaches to diagnose AMS easily and accurately are needed.

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.

The Effect of Aerobic Exercise on Intraocular Pressure in Horse

The present study was planned to investigate the effect of the intensity of exercise on intraocular pressure (IOP), systolic and diastolic blood pressure, glycaemia and blood lactate concentration in regularly trained Italian saddle jumper horses. On the first day five female horses performed 1 h of walking on an electronically controlled horse-walker at 100 m/min; on the second day 1 h session consisted of 5 min of walk, 30 min of trot, 20 min of gallop and one exercise of a 300 m long trail with eight jumps 90 cm high to be run in 1 min. The studied indicators were collected at rest, immediately after the exercise and 30 min after the exercise. Analysis of variance (ANOVA) showed a significant effect of different workloads on blood lactate concentration, systolic and diastolic blood pressure. No significant difference was found in IOP reduction when comparing aerobic and moderate anaerobic exercise. Our results confirm that the lack of a significant change in IOP in the athletic horse after mild exercise is in accordance with the human athlete. The cardiovascular and haematological changes induced by aerobic and moderate anaerobic exercise had no significant effect on IOP, either.

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.

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.

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.

COMPARISON OF THE EFFECTS OF ACUTE AND REGULAR EXERCISE ON INTRAOCULAR PRESSURE IN TURKISH ATHLETE AND SEDENTARIANS

The aim of this study was to investigate the changes that take place in IOP in athletes and people leading sedentary lives subjected to aerobic and anaerobic exercise and how chronic exercise could affect these changes. The study included 20 sportsmen (Group 1), and 20 people leading sedentary lives (Group 2). The intensity of the exercise for both groups was determined according to the Karvonen protocol and executed as an aerobic exercise program involving running on a treadmill for 30 min. Subjects in both groups were subjected to anaerobic exercise according to the Wingate test protocol for 30 s. The intraocular pressure of all subjects before exercise and after aerobic and anaerobic exercise were measured. The IOP before and after exercise aerobic and anaerobic were evaluated by the Willcoxon test whereas the right and left IOP before exercise and after the aerobic and anaerobic exercise programs in both groups were evaluated using the Mann Whitney U test. p values of <.05 were considered significant. Significant differences were found when the pre-exercise and post-aerobic and anaerobic exercise IOPs of the groups were compared (p < .05). Comparison of the post-anaerobic and aerobic exercise revealed a fall in the IOPs of the subjects after the aerobic exercise (p < .01). In this study, exercise was found to lead to a fall in the IOP in both sportsmen and those leading sedentary lives with the fall less apparent under anaerobic conditions than under aerobic conditions. In conclusion, therefore, it can be said that in those with an increased intraocular pressure, regular, moderately intense aerobic exercise rather than short-lived intense exercise could be more useful.

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.

Effects of submaximal exercise with water ingestion on intraocular pressure in healthy human males

The effects of exercise and water replacement on intraocular pressure (IOP) have not been well established. Furthermore, it is not known whether the temperature of the fluid ingested influences the IOP response. In the present study we determined the effect of water ingestion at three temperatures (10, 24 and 38 degrees C; 600 ml 15 min before and 240 ml 15, 30 and 45 min after the beginning of each experimental session) on the IOP of six healthy male volunteers (age = 24.0 +/- 3.5 years, weight = 67.0 +/- 4.8 kg, peak oxygen uptake (VO2peak) = 47.8 +/- 9.1 ml kg-1 min-1). The subjects exercised until exhaustion on a cycle ergometer at a 60% VO2peak in a thermoneutral environment. IOP was measured before and after exercise and during recovery (15, 30 and 45 min) using the applanation tonometry method. Skin and rectal temperatures, heart rate and oxygen uptake were measured continuously. IOP was similar for the right eye and the left eye and increased post-water ingestion under both exercising and resting conditions (P<0.05) but did not differ between resting and exercising situations, or between the three water temperatures. Time to exhaustion was not affected by the different water temperatures. Rectal temperature, hydration status, heart rate, oxygen uptake, carbon dioxide extraction and lactate concentration were increased by exercise but were not affected by water temperature. We conclude that IOP was not affected by exercise and that water ingestion increased IOP as expected, regardless of water temperature.

Complementary and alternative medicine for glaucoma

Given the recent interest in complementary and alternative medicine (CAM), some patients may seek such treatments to supplement their traditional glaucoma management. The prevalence of CAM use for glaucoma is approximately 5%. We reviewed the literature to determine the potential benefit of various alternative treatments. Aside from a temporary osmotic effect from high dose intravenous ascorbic acid, there is no evidence that megavitamin supplementation has a beneficial effect on glaucoma. During exercise, autoregulation in healthy eyes seems to maintain a consistent blood flow rate to the optic nerve despite fluctuations in intraocular pressure (IOP). In a glaucomatous eye, the very modest IOP-lowering that follows exercise may be offset by the initial elevation in IOP that occurs when one first initiates exercise. At this time, there is no evidence to encourage or discourage the use of special diets, acupuncture, relaxation techniques, or therapeutic touch specifically for the treatment of glaucoma. Very little research has been done on the majority of herbal remedies with regard to their treatment of glaucoma. Marijuana can cause a profound lowering of IOP, but the high nonresponse rate, short half life, and significant toxicity are strong indicators that it is not an appropriate therapeutic agent. Ginkgo biloba and some other Chinese herbal remedies do not affect IOP, but may improve blood flow to the optic nerve and, as such, may have a beneficial effect on glaucoma. These agents have recognized toxicities. Although there are some well-designed studies of alternative treatments, many of the recommendations for using alternative treatments are currently unsupported by the data provided.

Intraocular pressure changes: the influence of psychological stress and the Valsalva maneuver

The effects of psychological stress and the Valsalva maneuver on short-term variations of intraocular pressure (IOP) were studied in 49 healthy adults. Psychological stress consisted of mental arithmetic tasks presented in counterbalanced order by computer and by the experimenter. Additionally, a standardized Valsalva maneuver was performed (in counterbalanced order with the psychological stressors). IOP was measured with a Goldmann tonometer before and after performance of each stressor. All three stressors transiently and highly significantly increased IOP, although the Valsalva maneuver produced changes of a greater magnitude (10.2 mmHg) than the psychological stressors (1.3 mmHg). Subjective stress ratings and heart rate increased in response to all stressors. There were no effects of task sequence, eye muscle tension, sex, smoking status (some smokers misreported their smoking status), or regular marijuana use, but regular physical exercise was associated with less IOP increase during psychological stress.