Acute Intraocular Pressure Responses to Reading: The Influence of Body Position

Exploring the relationship between accommodation and intraocular pressure: a systematic literature review and meta-analysis

PURPOSE

To investigate the relationship between accommodation and intraocular pressure (IOP).

METHODS

Systematic literature search and meta-analysis following PRISMA guidelines was conducted on studies analyzing the relationship between accommodation and intraocular pressure. After removal of duplicates, title and abstract screening, full-text analysis was performed to select relevant articles and meta-analysis was then conducted as well.

RESULTS

Of the 1357 records identified, 17 met the selection criteria and were included. Overall, all studies showed that accommodation can influence IOP levels and meta-analysis indicated a significant IOP reduction of 1.10 mmHg (95%CI, -1.77; -0.42) following accommodative stimulus in healthy individuals, albeit with high heterogeneity among studies. Differences in IOP changes between emmetropic and progressing myopic individuals were not significant. Controversial results were obtained in patients with glaucoma with significantly lower IOP fluctuations being noted in eyes with previous trabeculectomy; however, the clinical heterogeneity of enrolled patients among studies made it not possible to combine results. Type of accommodative task, extraocular muscle contraction, head and body position all could potentially play a role in the measured IOP changes with, interestingly, near reading on a smartphone suggesting IOP increase.

CONCLUSION

Accommodation has an impact on IOP measurements and, overall, determines IOP decrease in healthy individuals. While such variations might not hold clinical significance for individuals in good health, their impact in patients with glaucoma should be considered. Further studies focused on specific components of such relationship are required to elucidate their individual impact and to define their potential role as non-pharmacological strategies to reduce IOP levels in selected patient categories.

Intraocular Pressure Changes While Reading Smartphone Digital Text Versus Printed Text in Healthy Individuals and those with Glaucoma

PRCIS

Reading results in a rise in intraocular pressure (IOP) which is greater while using smartphones compared with printed text among healthy and individuals with medically controlled primary open angle glaucoma (POAG).

PURPOSE

To compare the effect of reading for 30 minutes using smartphone and printed text on IOP.

PATIENTS AND METHODS

Sixty healthy volunteers and 22 patients with medically controlled POAG were asked to perform reading tasks using printed text followed by digital (smartphone) text under standardized conditions. IOP assessment was done using a rebound tonometer at baseline and subsequently at 10, 20, and 30 minutes of reading and 10 and 20 minutes post completion of reading tasks. IOP variations from baseline were measured and compared. Paired and independent ' T ' test analysis was performed to study IOP variations, and a P -value <0.05 was considered statistically significant.

RESULTS

The mean baseline IOP among volunteers and patients withPOAG was 14.58 (±2.91) and 15.02 (±2.18) mmHg, respectively. There was a rise in IOP in all participants with reading using either of the modalities, which normalized after 20 minutes of cessation. There was a statistically significant difference in rise in IOP from baseline between the 2 modalities (printed text reading and smartphone reading) at 20 minutes {+0.78 & +2.01 ( P =0.002)} and 30 minutes {+0.64 & +1.72 ( P =0.004)} among healthy volunteers and at 20 minutes {+0.78 & +2.01 ( P =0.002)} among POAG patients.

CONCLUSION

Reading is associated with the rise in IOP in both healthy volunteers and POAG individuals. The IOP rise is more marked with smartphone compared with printed text reading.

Differences Between Angle Configurations in Different Body Positions by Ultrasound Biomicroscopy in Patients with Cortical Age-Related Cataract

Purpose

To investigate the differences in parameters related to angle configuration and lens position in patients with cortical age-related cataract by ultrasound biomicroscopy (UBM) in different body positions.

Methods

Prospective study with 55 patients with cortical age-related cataract proposed for phacoemulsification, examined using a Compact Touch STS UBM (Quantel Medical, France). UBM bag/balloon technology was applied to measure the central anterior chamber depth (ACD) and lens vault (LV) in horizontal and vertical orientation in sitting and supine positions, angle opening distance (AOD500), trabecular iris angle (TIA) and iris lens angle (ILA) in four quadrants: superior, inferior, nasal, and temporal.

Results

We found no significant difference in ACD between sitting and supine positions (p = 0.053); LV was significantly greater in the supine position (p < 0.001); AOD500 in superior and inferior quadrants were significantly longer in the sitting position (p = 0.001; p < 0.001); TIA in superior and inferior quadrants was significantly greater in the sitting position (p < 0.001; p < 0.001), and TIAmax-min was significantly smaller in the sitting position (p = 0.001); ILA in temporal quadrant was significantly larger in the sitting position (p = 0.015) and ILAmax-min was significantly smaller in the sitting position (p < 0.001).

Conclusion

The anterior chamber angle was narrower and the lens was positioned more anteriorly in the supine than in the sitting position in cortical age-related cataract. Different positions may affect the angle configuration and the relative space of lens through different directions of mechanics and modes of action.

Influence of the body positions adopted for resistance training on intraocular pressure: a comparison between the supine and seated positions

OBJECTIVES

A variety of factors are known to mediate on the intraocular pressure (IOP) response to resistance training. However, the influence of the body position adopted during resistance training on IOP remain unknown. The objective of this study was to determine the IOP response to the bench press exercise at three levels of intensity when performed in supine and seated positions.

METHODS

Twenty-three physically active healthy young adults (10 men and 13 women) performed 6 sets of 10 repetitions against the 10-RM (repetition maximum) load during the bench press exercise against three levels of intensity (high intensity: 10-RM load; medium intensity: 50% of the 10-RM load; and control: no external load) and while adopting two different body positions (supine and seated). A rebound tonometer was employed to measure IOP in baseline conditions (after 60 s in the corresponding body position), after each of the 10 repetitions, and after 10 s of recovery.

RESULTS

The body position adopted during the execution of the bench press exercise significantly affected the changes in IOP (p < 0.001, η_p² = 0.83), with the seated position providing lower increases in IOP levels compared to the supine position. There was an association between IOP and exercise intensity, with greater IOP values in the more physically demanding conditions (p < 0.001, η_p² = 0.80).

CONCLUSIONS

The use of seated positions, instead of supine positions, for the execution of resistance training should be prioritized for maintaining more stable IOP levels. This set of findings incorporates novel insights into the mediating factors on the IOP response to resistance training. In future studies, the inclusion of glaucoma patients would allow to assess the generalizability of these findings.

Does body position, age, and heart rate induce IOP's changes?

OBJECTIVES

The main goal of this research was to determine the differences between the values of intraocular pressure (IOP) in the supine and sitting positions, and to assess the effect of age and cardiovascular parameters.

METHODS

Seventy-two healthy adults were enrolled and classified into age groups: 20-30 years (group A), 31-40 years (group B), and 41-71 years (group C). Corneal biometry and cardiovascular parameters, such as heart rate (HR), were measured. IOP measurements were taken in the sitting position (IOP_S) and in the supine position (IOP_L) using the iCare^® Pro tonometer.

RESULTS

A significant difference between the IOP_S and IOP_L in the entire cohort was found (p < 0.001). Regarding the age subgroups, a significant difference (p < 0.001) between the IOP_S and IOP_L was obtained in group A (2.6 ± 1.6 mmHg) and group C (1.5 ± 1.3 mmHg). There were no significant differences in the IOP_S between groups. The highest IOP values were obtained for group A. The correlations between HR and IOP_S are statistically significant for group A and group B, and for HR and IOP_L-S for group B only. Multivariate analysis showed that HR has a significant influence on the difference in IOP in the two body positions.

CONCLUSION

A statistically significant difference between the effect of age and the values of IOP_S and IOP_L was shown. Cardiovascular parameters showed some relevant statistical dependencies, but with a rather marginal significance in young people. The influence of body position for the measurement of IOP for healthy subjects does not seem to matter, despite the fact that there are some dependencies that are statistically significant.

Intraocular pressure fluctuation during resistance exercise

Objective

To evaluate the effect of weightlifting (leg press) on intraocular pressure (IOP).

Design

Prospective cohort study.

Subjects

A total of 24 participants met the inclusion criteria and completed the study procedures. Participants had an average age of 22.7±2.7 years and included nine women. The mean baseline IOP was 13.9 mm Hg (SD=2.4) with an average body mass index of 24.5 (SD= 3.1).

Methods

The maximum load for a single lift was found for each participant. Participants then performed three leg press regimens: one repetition using 95% of maximal load (1RM), six repetitions using 75% of maximal load (6RM) and isometric push against a weight much heavier than maximal load (ISO).

Main outcome measure

IOP was measured pre-exercise, during and immediately following the exercise using an iCare TA01i rebound tonometer. Blood pressure and HR were being monitored continuously during the lift. Optical coherence tomography images were obtained pre and postexercise session.

Results

The average maximum weight lifted by our participants was 331.9 Kg (SD=97.3). Transient increased IOP was observed across the 1RM, 6RM and ISO exercises with an average increase in 26.4 mm Hg (23.7 mm Hg to 28.7 mm Hg) to reach an average max IOP of 40.7 mm Hg (27.8 mm Hg to 54.2 mm Hg), with an absolute maximum of 70 mm Hg in one participant.

Conclusions

There is a transient and dramatic fluctuation in IOP with resistance training. This coupled with regular exposure to resistance training is potentially a significant risk factor for glaucoma. It should be noted that this study has been carried out in a healthy young population, and, thus, the external validity of these results in glaucoma participants requires further investigation.

Outcome, influence factor and development of CLS measurement in continuous IOP monitoring: A narrative review

A large fluctuation in intraocular pressure (IOP) and a high peak IOP remain the risk factors for progressive visual field loss in patients with glaucoma, which is a leading cause of irreversible blindness. However, IOP measurements during working time cannot provide sufficient information on IOP to guide clinicians in setting IOP target values. Contact lenses are extensively used in ophthalmology to correct the refractive error, and recently, they are serving as platforms for detection and drug delivery. Contact lens sensor (CLS) is a feasible and promising approach to continuously monitor IOP, with superior tolerance, non-invasiveness, and without sleep disturbance. The present work reviewed the associations between progressive course and Triggerfish® CLS outputs as well as the relationship between treatments and Triggerfish® CLS outputs. Moreover, it further summarized state-of-the-art CLS devices of the past decade.

Intraocular pressure increases during dynamic resistance training exercises according to the exercise phase in healthy young adults

PURPOSE

To determine the intraocular pressure (IOP) changes caused by the execution of lower body and upper body resistance training exercises leading to muscular failure depending on the exercise phase (concentric vs. eccentric). We also assessed the influence of the exercise type (back squat vs. biceps curl) and level of effort on the IOP response.

METHODS

Nineteen physically active young adults performed four sets (2 exercise type × 2 exercise phase) of 10 repetitions leading to muscular failure while adopting a normal breathing pattern. IOP was measured by rebound tonometry at baseline, after each of the ten repetitions, and after 1 min of recovery.

RESULTS

There was a main effect of the exercise phase (p < 0.001, η² = 0.56), observing greater IOP values in the eccentric condition of the back squat and concentric condition of the biceps curl. Also, greater IOP values were obtained for the back squat in comparison with the biceps curl (p < 0.001, η² = 0.61), and IOP progressively increases with the level of accumulated effort (p < 0.001, η² = 0.88; Pearson r = 0.97-0.98).

CONCLUSIONS

IOP fluctuates during the different phases of the repetition in dynamic resistance training exercises, being greater IOP values observed during the more physically demanding phases of the exercise (eccentric phase of the back squat and concentric phase of the biceps curl). A heightened IOP response is positively associated with muscle size (back squat > biceps curl) and with the level of effort (number of accumulated repetitions). Based on these findings, highly demanding dynamic resistance training should be avoided when maintaining stable IOP levels is desirable.