Essilor (France)

Light plays a crucial role in human biology. However, while the general pathways involved in light perception are well-understood, the specific neural mechanisms explaining why some individuals experience an adverse behavioral response to light (hypersensitivity), while others rather the opposite (hyposensitivity) remain unclear. Here, leveraging the high temporal resolution of EEG, we set out to test the hypothesis that, in hyposensitive individuals, an excessive sensory stimulation may lead to neural hyper-excitability. Such an enhanced response, in turn, might be key to mitigate discomfort. We conducted our study on 21 participants, who underwent light exposure tests at varying intensities. Our findings revealed that hyposensitive individuals, who are less averse to intense light exposure, can rely on a more efficient neuroprotective mechanism against sensory overload, when compared to hypersensitive individuals. Such a mechanism is mainly and consistently expressed through the increase in power of beta and gamma oscillations, along with a delayed onset of the P100 component in response to light stimuli. These findings open the door for future research to adaptive technologies that utilize EEG markers to create personalized, real-time interventions for light sensitivity, such as adaptive wearable devices or environmental systems that dynamically adjust lighting based on neural feedback, providing immediate relief for hypersensitive individuals.

Introduction: Research has demonstrated links between driving ability and perceptual-cognitive abilities. Such research is typically conducted in older adult populations due to well-established cognitive decline even in healthy ageing. Still, some authors have argued that the relationship should not be neglected in younger drivers. This study investigated whether training three-dimensional multiple object tracking (3D-MOT)—a dynamic, speeded tracking task soliciting multiple forms of attention and speed-of-processing—would produce beneficial transfer to measures of simulated driving performance and whether the effect might vary in older and younger adults. Methods: 34 subjects (20 young adult, 14 older adult) divided into 3D-MOT and active control groups were recruited and trained twice weekly for 5 weeks during 30-minute laboratory sessions (10 total). Pre- and post-training driving performance was assessed using previously-validated objective driving measures on driving simulator scenarios pre-programmed with dangerous events necessitating participants to react appropriately to avoid collisions. Results: Younger and older adults exhibited very different learning outcomes on the specific 3D-MOT training paradigm employed in this study, suggesting it may not have been optimal for both age groups. This appeared to be further reflected in differential training transfer outcomes. Nevertheless, analysis of covariance revealed a statistically significant increase in the distance at which participants trained using 3D-MOT finished executing braking maneuvers in response to dangerous events compared to active controls [F(1,29) = 4.59, p = .041, η2p = .14]. Conclusion: The findings are consistent with the idea that 3D-MOT training enhances perceptual-cognitive ability and that this can translate to quicker reactions during a simulated driving task. This result provides a rationale for future studies examining whether such training may produce long-term improvements in driver safety in the real world.

This chapter aims to estimate the myopia among school children of Bangalore region, Karnataka, India. Myopia is one of the most common visual problems that affects both children and adults. High myopia increases the risk of developing irreversible vision loss due to pathologic changes in the retina, as well as the risk of glaucoma, cataract, and amblyopia. The current study included students aged 5 to 15 years from urban and rural schools in the Bangalore region. A total of 3038 students were screened from six different schools, with 1510 girls and 1528 boys. The students were subjected to basic eye examinations such as visual acuity and dry retinoscopy. In addition, the power of the glasses the children were already wearing for the past correction was recorded. According to the findings of this study, 4% (241) of the 6076 eyes screened had myopia. Myopia affected 3.18% (94) of 2954 rural children and 4.71% of 3122 urban children. It was concluded that urban school children in Bangalore, Karnataka, had a higher frequency of myopia than rural school children.

ABSTRACT Purpose To assess the performance of a new device for the clinical determination of light discomfort on a large sample of healthy human subjects. Methods A total of 489 subjects ranging from 20 to 70 years old (241 men, 248 women) were evaluated with the LUMIZ™ 100 to determine light discomfort. Repeatability was assessed by means of within-subject standard deviation, coefficient of variation (CoV), and intraclass correlation coefficient (ICC). Repeated measures ANOVA, Kruskal-Wallis, and correlation analysis were applied to test for differences between repeated measures, and effect of age on reliability. Results Discomfort thresholds obtained are well distributed across the light intensity range available (25 to 10211 lux). Intrasession ICCs are higher than 0.849 for all thresholds, and 85% of CoV are below 10%. Thresholds obtained in the first set of measurements are highly correlated with the median of three sets (r2 > 0.8). Intersession, 64% of CoV are below 10%. Age does not affect discomfort thresholds (p = 0.30), nor affect reliability (variance on CoV, p = 0.368) Conclusions The new device provides good intrasession repeatability for the clinical determination of light discomfort thresholds, although variance is slightly greater between sessions. The system is useful for the clinical determination of light discomfort.

There is growing evidence of the negative impact of light at night (LAN) on sleep. The low levels of blue light emitted by screens and domestic lighting are sufficient to induce strong melatonin suppression on young adults. Only broadband dark-orange lenses evidenced to limit this effect but with highly compromised vision. We performed a cross-over randomized clinical study in the evening home environment on young adults to compare the effects of an innovative selective filter of circadian light to non-filtering lenses and to dark-orange lenses (dark positive control) on sleep quality, melatonin production and visual comfort. Participants were evening screen users devoid ofany major health problem and excluded for prescription medications or sleep disruption. Each eyewear was worn 7 consecutive evenings for 4 hours prior to the usual bedtime using screens, with 7 days of wash-out in between. Hourly saliva samples (Bühlmann) were collected and radioimmuno-assayed for melatonin concentration. Sleep staging was analyzed with a digital tri-axial accelerometer (MotionWatch). Sleep and day alertness were assessed with standard Leeds and Karolinska Sleepiness Scale. Visual comfort and lens aesthetics were rated. MANOVA with Tukey tests were used for statistical analysis. 56 healthy young adults (27.9yrs ± 5.8SD) participated. 4-hour exposure to light from screens and domestic lighting with non-filtering lenses before bedtime significantly suppressed melatonin by 47% compared to the dark condition. Our selective filter reduced the suppression to 12% (p<0.001), improved objectively measured sleep duration by 27 min (p<0.001) and advanced L5 onset by 25 min (p<0.001). Leeds scores were increased with both filters, especially sleep quality (p<0.001). The visual experience was significantly improved with the selective filter compared to the darkorange one. We bring confirmatory proof that low levels of LAN are sufficient to decrease sleep quality and melatonin production at bedtime, likely to lead to misalignment of circadian phase. Our highly selective filter significantly counteracted these effects, while considerably improving vision and lens aesthetics compared to current dark-orange lenses. ESSILOR RESEARCH FRANCE

Due to their narrow reflection peak as well as their compact structure, Guided Mode Resonance Filters (GMRFs) are attractive for many applications. We demonstrate the possibility to modulate the properties of a GMRF by associating with liquid crystals (LCs). By impregnating the diffraction grating with LCs, it is possible to switch between an active and an inactive state depending on the polarization of the light or the applied voltage. In this paper we fabricated and characterized the first diffraction order of LC-impregnated gratings with different periods (0,8 to 5,0µm) and depths (130 to 840nm) to test the ability of liquid crystals to adjust the diffraction properties. Finally, 99.8% of diffraction turn off with a 90° rotation polarization at zero voltage and 90 to 99% by applying a voltage of 30 V according to the grating dimensions. The effect of the grating dimension on the diffraction modulation capacity will be discussed.

Introduction : Beyond their refractive distinction, Myopes and Emmetropes show behavioral differences, especially in the presence of blur. Our study's aim is to compare cortical responses in the primary visual cortex (V1) between the two populations and explore correlations with optometric measurements. Protocol : We studied 21 young adults (18 to 35 years), including 10 Myopes and 11 Emmetropes. The total wavefront aberration with natural pupil diameter is measured for both eyes without correction. Once equipped with their visual correction, they undergo an fMRI exam at 3T. This includes a sequence of retinotopy and stimulation for 18s, viewing natural images or tables of optotypes, either sharp or with a 2 diopter artificial blur. To maintain the subject's attention, a detection task of gradual reversal of blur level was introduced at the end of the stimulation (last 6 seconds). Analysis : Data were processed with BrainVoyager and Matlab. The parts of V1 corresponding to the fovea, the perifovea and 3° of eccentricity, were located for each subject. Then cortical activity was integrated over the static stimulation duration. Values obtained were compared with optometric measures. Results : The main significant correlations are between the mean total wavefront aberration of both eyes (rms) and perifovea. For Myopes correlations are for sharp scenes (left, right and both hemisphere R ² = 0.64, p = 0.01) and sharp optotypes (right and both hemisphere R ² = 0.58, p = 0.01). For Emmetropes correlations are significant only for the left hemisphere activity for sharp optotypes (R ² = 0.46, p = 0.02) and sharp scenes (R ² = 0.38, p = 0.04). Conclusion : The level of cortical activity of V1 corresponding to the perifovea of corrected Myopes remains correlated with the total wavefront aberration, when taking into account both ametropia and pupil diameter. This correlation is much weaker for Emmetropes. Meeting abstract presented at VSS 2014