Raimundo Jiménez

Interocular Differences in Higher-order Aberrations on Binocular Visual Performance

Purpose. To analyze the influence of higher-order aberrations on binocular visual performance under mesopic conditions. Methods. We measured aberrations in both eyes of 35 emmetropic observers with a Wasca aberrometer. Binocular visual performance was checked with both binocular summation for contrast sensitivity function and a parameter that characterizes stereopsis (maximum disparity). Results. Binocular summation and maximum disparity significantly decrease with increasing interocular differences in higher-order aberrations (total, coma, and spherical aberration). Conclusions. At least some aspects of binocular visual performance are less effective for large interocular differences in higher-order eye aberrations.

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.

Prevalence of Refractive Errors in School-Age Children in Burkina Faso

The prevalence of myopia and refractive errors is known to vary among different societies, and these differences may be attributed partly to differences in genetic background and partly to environmental factors, especially the amount of near work performed. The goal of this study was to determine the prevalence of refractive errors in school-age children in Burkina Faso, west-central Africa, whose population is largely illiterate, with nonurban customs and lifestyle.

Prevalence of refractive errors in children in Equatorial Guinea.

Purpose The aim of this work is to evaluate the epidemiological aspects of the refractive errors in school-aged children in Malabo (Island of Bioko), Equatorial Guinea (western-central Africa). Methods A total of 425 schoolchildren (209 male subjects and 216 female subjects, aged between 6 and 16 years) were examined to evaluate their refraction errors in Malabo, Equatorial Guinea (western-central Africa). The examination included autorefraction with cycloplegia, measurement of visual acuity (VA) for far vision, and the curvature radii of the main meridians of the anterior surface of the cornea. Results A low prevalence of myopia was found (⩽−0.50 diopters [D] spherical equivalent), with unilateral and bilateral myopia being 10.4 and 5.2%, respectively. The prevalence of unilateral and bilateral hypermetropia (≥2.0 D spherical equivalent) was 3.1 and 1.6%, respectively. Astigmatism (⩽−0.75 D) was found in unilateral form in 32.5% of these children, whereas bilateral astigmatism was found in 11.8%. After excluding children having any ocular pathology, the low prevalence of high refractive errors signified good VA in these children. Significant differences were found in the distribution of the refractive errors by age and type of schooling (public or private) but not by sex. In general, the radii of the anterior of the cornea did not vary significantly with age. Conclusions The mean refractive errors found were low and therefore VA was high in these children. There was a low prevalence of myopia, with significantly higher values in those who attended private schools (educationally and socioeconomically more demanding). Astigmatism was the most frequent refractive error.

Optical quality and vision with iris-coloring soft contact lenses.

Purpose To study the influence of iris-coloring soft contact lenses, designed for changing apparent iris color, on optical quality and vision. Methods Eighty subjects were included in this study. All participants were classified as emmetropic, with monocular best-corrected visual acuity of 20/20 or better. For 40 subjects, we measured the optical quality (aberrations, the Strehl ratio, and the objective scattering index) and visual performance before and after wearing the cosmetic soft contact lenses. We also measured the optical quality and visual performance for the other 40 subjects but with a different kind of lens (fantasy soft contact lenses). Results Iris-coloring soft contact lenses significantly increased coma-like and total higher-order aberrations and objective scattering index (p < 0.05). We also found a significant deterioration in the Strehl ratio. The contrast sensitivity function significantly decreased only after wearing the fantasy soft contact lenses (p = 0.047). Conclusions Iris-coloring soft contact lenses deteriorate the optical quality and worsen the contrast sensitivity function. Iris-coloring soft contact lens wearers should be informed about the effects on optical quality and visual function.

Ametropias in school-age children in Fada N'Gourma (Burkina Faso, Africa).

Purpose. To assess epidemiological aspects of refractive errors in school-age children in Burkina Faso (west-central Africa). Methods. A total of 315 school children (ranging from 6 to 16 years of age and belonging to different ethnic groups) taken at random from two urban schools in eastern Burkina Faso were examined to assess their refractive error, which was determined by non-cycloplegic retinoscopy with optical fogging. The standard Refractive Error Study in Children (RESC) definitions of refractive errors were used: myopia ≤−0.5 D spherical equivalent (SE) in at least one eye, hyperopia ≥2 D SE in at least one eye, astigmatism ≤−0.75 D cylinder in at least one eye, and anisometropia ≥1 D SE difference between the two eyes. Results. Unilateral myopia and bilateral myopia were found in 2.5 and 1%, respectively; unilateral hyperopia in 17.1%, bilateral hyperopia in 8.6%; astigmatism in at least one eye in 11.7%. The highest prevalence value (18.4%) of astigmatism (≤−0.75 D) in at least one eye was found in the Gourmantché ethnic group. The low prevalence of large refractive errors makes visual acuity in these children very good (visual acuity logarithm of the minimum angle of resolution −0.073 ± 0.123 SD). Conclusions. There was a low prevalence of myopia in these African school children. Clinically significant high hyperopia (≥+2 D SE) was also uncommon. There were no significant differences between the distributions of refractive errors according to gender or ethnicity. With respect to age groups, the prevalences of hyperopia and astigmatism were significantly higher in the younger age groups.

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.

Optical quality and visual performance after cataract surgery with biaxial microincision intraocular lens implantation

Purpose To evaluate the time course of the optical quality and visual performance with a microincision monofocal intraocular lens (Incise). Setting Hospital Torrecárdenas, Almería, Spain. Design Prospective study. Methods The visual and refractive outcomes were evaluated in eyes with the microincision IOL preoperatively and 1, 3, and 6 months postoperatively. The modulation transfer function (MTF) cutoff frequency, Strehl ratio, and objective scatter index (OSI) were used to measure optical quality. The contrast sensitivity function (CSF) and the visual disturbance index characterized visual performance. Results In the 32 study eyes, the mean values preoperatively and 6 months postoperatively, respectively, were MTF cutoff frequency (11.40 cycles per degree [cpd] ± 8.39 [SD] and 23.33 ± 11.68 cpd; P < .001), Strehl ratio (0.078 ± 0.32 and 0.15 ± 0.07; P < .05), and OSI (7.44 ± 3.25 and 1.57 ± 0.26; P < .001). At each spatial frequency, the CSF significantly differed between preoperatively and postoperatively (P < .001). The mean visual disturbance index changed from 0.70 ± 0.28 to 0.31 ± 0.17 (P < .001). For all parameters studied, statistically significant differences were found between the preoperative and postoperatively values, with no differences between the results 1, 3, and 6 months after surgery (P > .05). Conclusions Biaxial microincision cataract surgery provided optimum clinical outcomes. The optical quality and visual performance improved significantly 1 month after surgery, with the results remaining stable at 6 months. The postoperative visual function was similar to that in subjects of the same age with healthy eyes. Financial Disclosure None of the authors has a financial or proprietary interest in any material or method mentioned.

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