Jesús Vera

Driving time modulates accommodative response and intraocular pressure

Driving is a task mainly reliant on the visual system. Most of the time, while driving, our eyes are constantly focusing and refocusing between the road and the dashboard or near and far traffic. Thus, prolonged driving time should produce visual fatigue. Here, for the first time, we investigated the effects of driving time, a common inducer of driver fatigue, on two ocular parameters: the accommodative response (AR) and the intraocular pressure (IOP). A pre/post-test design has been used to assess the impact of driving time on both indices. Twelve participants (out of 17 recruited) completed the study (5 women, 24.42±2.84years old). The participants were healthy and active drivers with no visual impairment or pathology. They drove for 2h in a virtual driving environment. We assessed AR and IOP before and after the driving session, and also collected subjective measures of arousal and fatigue. We found that IOP and AR decreased (i.e., the accommodative lag increased) after the driving session (p=0.03 and p<0.001, respectively). Moreover, the nearest distances tested (20cm, 25cm, and 33cm) induced the highest decreases in AR (corrected p-values<0.05). Consistent with these findings, the subjective levels of arousal decreased and levels of fatigue increased after the driving session (all p-values<0.001). These results represent an innovative step towards an objective, valid, and reliable assessment of fatigue-impaired driving based on visual fatigue signs.

Intraocular Pressure Responses to Maximal Cycling Sprints Against Different Resistances: The Influence of Fitness Level

Purpose: This study investigated the acute effect of maximal cycling sprint against difference resistances on intraocular pressure (IOP) depending on participants’ fitness level. Methods: In total, 26 physically active collegiate men performed 5 maximal cycling sprints against different resistances in a randomized order, and IOP was measured immediately before and after each sprint. Participants were divided in 2 subgroups (low fit and high fit) according to their maximum power output relative to body weight to assess the influence of fitness level. Two identical testing sessions were performed to assess the repeatability of IOP values. Results: We found that IOP decreases with the lightest resistance (P<0.01), whereas IOP increases with heavier resistances (P<0.01), and it showed a positive linear tendency (r=0.99). Our results suggest that participants’ fitness level seems to influence IOP responses, with a more stable response in the high-fit group. A strong intersession repeatability of IOP values was observed (intraclass correlation coefficient range, 0.82 to 0.98; coefficients of variations range, 1.76% to 6.23%). Conclusions: We conclude that (1) IOP is sensitive to cycling resistance in all-out sprints, with a lowering effect on the lightest resistance and an increasing effect with medium and heavy resistances, (2) high fitness level is beneficial to avoid IOP fluctuations during sprints, and (3) these changes are comparable when measured on 2 different days under the same experimental conditions. A progressive involvement in physical activity may be desirable to avoid IOP peaks during highly demanding physical effort. Future studies are needed to clarify the consequences of exercise in glaucoma patients.

Effect of examination stress on intraocular pressure in university students

Intraocular pressure (IOP) has been investigated as a possible objective index of mental stressors. Here, we assessed the effect of examination stress on IOP in 33 university students. A repeated-measures design was used with two experimental conditions (examination and control) and two points of measurements (pre- and post-sessions). Also, the cardiovascular response, subjective perceived stress, as well as calculated ocular perfusion pressure and blood-pulse pressure were determined. A Bayesian statistical analysis showed higher IOP values in the examination in comparison to the control condition (BF01 < 0.001). A similar pattern was found for the cardiovascular indices (diastolic and systolic blood pressure, and heart rate), and these findings were corroborated by subjective reports (BF01 < 0.001 in all cases). Our data incorporates evidence in relation to the utility of IOP as an objective marker of examination stress, and it may help in the assessment and management of stress in applied scenarios.

Intraocular pressure increases after complex simulated surgical procedures in residents: an experimental study

BackgroundSurgeons’ overload is one of the main causes of medical errors that might compromise patient safety. Due to the drawbacks of current options to monitor surgeons’ load, new, sensitive, and objective indices of task (over)load need to be considered and tested. In non-health-care scenarios, intraocular pressure (IOP) has been proved to be an unbiased physiological index, sensitive to task complexity (one of the main variables related to overload), and time on task. In the present study, we assessed the effects of demanding and complex simulated surgical procedures on surgical and medical residents’ IOP.MethodsThirty-four surgical and medical residents and healthcare professionals took part in this study (the experimental group, N = 17, and the control group, N = 17, were matched for sex and age). The experimental group performed two simulated bronchoscopy procedures that differ in their levels of complexity. The control group mimicked the same hand-eye movements and posture of the experimental group to help control for the potential effects of time on task and re-measurement on IOP. We measured IOP before and after each procedure, surgical performance during procedures, and perceived task complexity.ResultsIOP increased as consequence of performing the most complex procedure only in the experimental group. Consistently, residents performed worse and reported higher perceived task complexity for the more complex procedure.ConclusionsOur data show, for the first time, that IOP is sensitive to residents’ task load, and it could be used as a new index to easily and rapidly assess task (over)load in healthcare scenarios. An arousal-based explanation is given to describe IOP variations due to task complexity.Graphical Abstract

Baseline Intraocular Pressure Is Associated With Subjective Sensitivity to Physical Exertion in Young Males

ABSTRACT Purpose: The purposes of this study were to (a) investigate the effect of physical effort (cycling for 60 min at 60 ± 5% of individually computed reserve heart-rate capacity), combined with 2 different levels of cognitive demand (2-back, oddball), on intraocular pressure (IOP) and subjective judgments of perceived exertion (ratings of perceived exertion [RPE]), affect (Affective Valence subscale of the Self-Assessment Manikin [SAM]), and mental workload (National Aeronautics and Space Administration Task Load Index [NASA-TLX]); and (b) ascertain whether baseline IOP, measured before exercise, is associated with individual differences in subjective assessments of effort and affective response during exercise. Method: Seventeen participants (Mage = 23.28 ± 2.37 years) performed 2 physical/cognitive dual tasks, matched in physical demand but with different mental requirements (2-back, oddball). We assessed IOP before exercise, after 2 min of active recovery, and after 15 min of passive recovery, and we also collected RPE and SAM measures during the sessions (28 measurement points). We used NASA-TLX and cognitive performance as checks of the mental manipulation. Results: (a) Intraocular pressure increased after concomitant physical/mental effort, with the effect reaching statistical significance after the 2-back task (p = .002, d = 0.35) but not after the oddball condition (p = .092, d = 0.29). (b) Baseline IOP was associated with subjective sensitivity to effort and showed statistical significance for the oddball condition (p = .03, ƞp2 = .622) but not for the 2-back task (F < 1). Conclusions: Results suggest a relationship between IOP and physical/cognitive effort, which could have implications for the management of glaucoma. Additionally, a rapid measure of IOP could be used as a marker of individual effort sensitivity in applied settings.

Acute intraocular pressure responses to high-intensity interval-training protocols in men and women

ABSTRACT We aimed (1) to test the acute impact of two high-intensity interval-training (HIIT) protocols differing in the level of effort on intraocular pressure (IOP) responses, and (2) to elucidate whether the IOP responses differ between men and women. Twenty-four physically active collegiate (12 men and 12 women) performed three protocols: low-fatigue HIIT (eight 30-m sprints with 60-s of rest), high-fatigue HIIT (eight 30-m sprints with 30-s of rest), and control (walking). IOP was taken at baseline, after sprints and recovery by rebound tonometry. Our data revealed an acute IOP reduction during both HIIT protocols compared to the control condition (effect size [ES]:0.81–1.65). The differences between both HIIT protocols were generally negligible (ES<0.30), however, the reduction of IOP was moderately higher for the low-fatigue HIIT protocol after the 7th (ES: 0.67) and 8th (ES: 0.74) sprints. Women showed a more prominent lowering effect on IOP during the control condition (ES: 0.42–1.02), and during the two first sprints of both HIIT protocols (ES: 0.54–1.03). These findings highlight that a time-efficient HIIT protocol may acutely reduce IOP levels, while low-fatigue HIIT protocol could be recommended since it induced a higher reduction on IOP than the high-fatigue HIIT protocol.

Effect of the level of effort during resistance training on intraocular pressure

Abstract Background: We aimed to evaluate the influence of the level of effort during four basic resistance exercises leading to muscular failure on intraocular pressure (IOP) and ocular perfusion (OPP), as well as the role of exercise type and sex. Methods: Twenty-five young adults (12 women) performed 10 repetitions against their 10-RM (repetition maximum) load in the squat, military press, biceps curl and calf raise exercises. IOP was measured before, during and after exercise, whereas OPP was indirectly assessed before and after each exercise. Results: There was a progressive IOP rise during exercise (p < 0.001, η² = 0.531), which was dependent on exercise type (p = 0.020, η² = 0.125). The squat exercise induced higher IOP increments in comparison to the other exercises (corrected p-values < 0.001), and higher IOP values were found for the military press and biceps curl than for the calf raise exercise (corrected p-values = 0.012 and 0.002). OPP exhibited a significant reduction when leading to muscular failure (p = 0.001, η² = 0.364), being statistically significant for the squat and military press exercises (corrected p-values = 0.037 and 0.047). No effect of sex was found for IOP and OPP (p > 0.05). Conclusions: A single set of resistance training leading to muscular failure causes an instantaneous and progressive IOP rise in healthy young individuals. These IOP rises depend on exercise type (squat > military press = biceps curl > calf raise), but not on participant´s sex. OPP diminished as a consequence of performing resistance training exercise, being statistically significant for the squat and military press exercises. Future studies should include glaucoma patients aiming to corroborate the generalizability of our findings.

Measuring mental workload: ocular astigmatism aberration as a novel objective index

Abstract This study assessed the effect of two perceptually matched mental tasks with different levels of mental demand on ocular aberrations in a group of young adults. We measured ocular aberration with a wavefront sensor, and total, internal and corneal RMS (root mean square) aberrations were calculated from Zernike coefficients, considering natural and scaled pupils (5, 4.5, and 4 mm). We found that total, internal and corneal astigmatism RMS showed significant differences between mental tasks with natural pupils (p < .05), and this effect was maintained with 5 mm scaled pupils (total RMS astigmatism, p < .05). Consistently, pupil size, intraocular pressure, perceived mental load and cognitive performance were influenced by the level of mental complexity (p < .05 for all). The findings suggest that ocular astigmatism aberration, mediated by intraocular pressure, could be an objective, valid reliable index to evaluate the impact of cognitive processing in conjunction with others physiological markers in real world contexts. Practitioner Summary: The search continues for a valid, reliable, convenient method of measuring mental workload. In this study we found ocular astigmatism aberration is sensitive to the cumulative effect of mental effort. It shows promise of being a novel ocular index which may help to assess mental workload in real situations.

Fitness Level Modulates Intraocular Pressure Responses to Strength Exercises

ABSTRACT Purpose/Aim: The execution of strength exercises has demonstrated to increase the intraocular pressure (IOP) levels, and it may have a negative impact on the ocular health. We aimed to explore the influence of fitness level on the acute IOP response to strength exercises performed under different loading conditions, as well as to test whether the IOP responses differ between the bench press and jump squat when performed against the same relative loads. Materials and Methods: Forty military personnel males were divided in two subgroups (20 high-fit and 20 low-fit) based on their relative to body mass one-repetition maximum (1-RM). Participants performed an incremental loading test in the bench press and jump squat exercises, and IOP was assessed before and after each repetition by rebound tonometry. Results: IOP increased immediately after executing both exercises (p < 0.01 in both cases), being the magnitude of the IOP increment positively and linearly associated with the increment of the load in both groups (i.e., high-fit and low-fit) and in both exercises (R2 range: 0.81–1.00). Higher fitness level attenuated the IOP rise produced by both exercises (p < 0.01 in both cases). The bench press induced higher IOP increments than the jump squat for both groups at relative loads of ~50%1-RM and ~60%1-RM (p < 0.01 in all cases). Conclusions: These data indicate that IOP increases as a consequence of performing strength exercises, being the increment accentuated with the increase of the load and in the bench press compared to the jump squat exercise. Of special importance would be that the IOP responses were significantly reduced in high-fit individuals. These findings should be addressed in glaucoma patients.

Visual function, performance, and processing of basketball players versus sedentary individuals

Background Athletes tend to have better visuo-motor performance than do sedentary individuals. However, several basic visual-function and perceptual parameters remain unexplored to date. In this study, we investigated whether differences exist in visual function, performance, and processing between basketball players and individuals without a sport-involvement background. Methods A total of 33 healthy men with no visual impairment or pathology were divided into 2 groups, depending on the involvement in sport (semi-professional basketball players and sedentary individuals). We tested their baseline heart-rate variability in the resting position apart from subjective questionnaires to determine their physical fitness level, and we checked their visual function, performance, and processing through an extended battery of optometric tests. Results The 2 groups differed in resting heart-rate variability parameters (p < 0.001), confirming their dissimilarities in regular time practising sports per week. The basketball players showed a closer breakpoint and recovery nearpoint of convergence, a higher fusional-vergence rate, better discriminability halos, and better eye–hand coordination (all p values < 0.05). Conclusion These results show evidence that athletes, basketball players in this case, exhibit better performance in several visual abilities in comparison to a group of individuals without sporting backgrounds, suggesting an improvement due to the systematic involvement of those skills during basketball practice.