Comparison of the influence of light between circularly polarized and linearly polarized smartphones on dry eye symptoms and asthenopia

Closing eyes with artificial tears: A simple and effective strategy to combat screen-related asthenopia and dry eye symptoms

Background

The widespread use of various video display terminals (VDTs) always had a detrimental impact on ocular health. Prolonged use of smartphones has been one of the leading causes of dry eye (DE) and asthenopia. Therefore, the purpose of this study is to find a simple and effective strategy to combat screen-related DE and asthenopia.

Methods

A group of healthy participants aged 18 and above were randomly assigned to three groups and tasked with a 2 h smartphone reading task. After 1 ​h of usage, each group adopted different methods of rest: no rest (Group A), a 10 min eye-closed rest (Group B), or a 10 min eye-closed joint artificial tears rest (Group C). Ophthalmological examinations and questionnaires were administered to all participants before and after the 2 h reading task.

Results

90 qualified volunteers, including 29 males and 61 females, were randomly assigned to three groups. Group A demonstrated a significant increase in the severity of DE and asthenopia as evidenced by all the evaluated indices. On the other hand, Group C did not exhibit any notable change in DE and asthenopia symptoms, with an improvement in corneal fluorescein staining (CFS) results (P ​> ​0.05) when compared to the pre-reading values. Group B showed a significant increase in ocular surface disease index (OSDI) (P ​≤ ​0.05) and a decrease in critical flicker frequency (CFF) (P ​≤ ​0.05).

Conclusions

Close-eye rest with artificial tears may be a convenient and effective prevention strategy for screen-related DE and asthenopia.

Switchable Dual Circularly Polarized Luminescence in Through-Space Conjugated Chiral Foldamers

Organic materials with switchable dual circularly polarized luminescence (CPL) are highly desired because they can not only directly radiate tunable circularly polarized light themselves but also induce CPL for guests by providing a chiral environment in self-assembled structures or serving as the hosts for energy transfer systems. However, most organic molecules only exhibit single CPL and it remains challenging to develop organic molecules with dual CPL. Herein, novel through-space conjugated chiral foldamers are constructed by attaching two biphenyl arms to the 9,10-positions of phenanthrene, and switchable dual CPL with opposite signs at different emission wavelengths are successfully realized in the foldamers containing high-polarizability substitutes (cyano, methylthiol and methylsulfonyl). The combined experimental and computational results demonstrate that the intramolecular through-space conjugation has significant contributions to stabilizing the folded conformations. Upon photoexcitation in high-polar solvents, strong interactions between the biphenyl arms substituted with cyano, methylthio or methylsulfonyl and the polar environment induce conformation transformation for the foldamers, resulting in two transformable secondary structures of opposite chirality, accounting for the dual CPL with opposite signs. These findings highlight the important influence of the secondary structures on the chiroptical property of the foldamers and pave a new avenue towards efficient and tunable dual CPL materials.

Efficient Ultraviolet Circularly Polarized Luminescence in Zero-Dimensional Hybrid Cerium Bromides

Ultraviolet circularly polarized luminescence (UV-CPL) with high photon energy shows great potential in polarized light sources and stereoselective photopolymerization. However, developing luminescent materials with high UV-CPL performance remains challenging. Here, we report a pair of rare earth Ce3+-based zero-dimensional (0D) chiral hybrid metal halides (HMHs), R/S-(C14H24N2)2CeBr7, which exhibits characteristic UV emissions derived from the Ce 5d-4f transition. The compounds show simultaneously high photoluminescent quantum yields of (32-39)% and large luminescent dissymmetry factor (|glum|) values of (1.3-1.5)×10-2. Thus, the figures of merits of R/S-(C14H24N2)2CeBr7 are calculated to be (4.5-5.8)×10-3, which are superior to the reported UV-CPL emissive materials. Additionally, nearly 91 % of their PL intensities at 300 K can be well preserved at 380 K (LED operating temperature) without phase transition or decomposition, demonstrating the excellent structural and optical thermal stabilities of R/S-(C14H24N2)2CeBr7. Based on these enantiomers, the fabricated UV-emitting CP-LEDs exhibit high polarization degrees of ±1.0 %. Notably, the UV-CPL generated from the devices can significantly trigger the enantioselective photopolymerization of diacetylene with remarkable stereoselectivity, and consequently yield polymerized products with the anisotropy factors of circular dichroism (gCD) up to ±3.9×10-2, outperforming other UV-CPL materials and demonstrating their great potential as UV-polarized light sources.

The Chinese version of the Computer Vision Syndrome Questionnaire: translation and cross-cultural adaptation

BACKGROUND

The Spanish version of the Computer Vision Syndrome Questionnaire (CVS-Q^©) is a validated instrument, with good psychometric properties, to measure Computer Vision Syndrome (CVS) in workers using Video Display Terminals (VDTs). To date, there are no known valid instruments in Chinese for the assessment of CVS despite the high exposure to VDTs at work that this population presents. For this, the purpose of this study is to translate and cross-culturally adapt the CVS-Q^© into Chinese.

METHODS

A study with five consecutive stages: direct translation, synthesis of translations, back translation, consolidation by a committee of experts, and pre-test. During the pre-test, a cross-sectional pilot study was conducted on VDT users (n = 44) who completed the Chinese version of the questionnaire plus an ad hoc post-test to assess the comprehensibility of the scale and to verify aspects of its applicability and feasibility. Data concerning sociodemographic information, general and ocular health, use of optical correction and varying exposure to VDTs was also collected.

RESULTS

The entire sample considered the Chinese version of the CVS-Q^© simple, clear, and easy to understand and 95.5% also found it easy to complete. 88.7% considered that the scale did not need any improvement. The final version of the Chinese scale to measure CVS was obtained (the CVS-Q CN^©). The mean age of participants was 31.3 ± 9.8 years, 47.6% were women, and 57.1% used VDTs to work for more than 8 h/day.

CONCLUSIONS

The CVS-Q CN^© can be considered an easy tool to assess CVS in workers exposed to digital devices in China. This version would facilitate research, its use in clinical practice, and the prevention of occupational hazards in the workplace.

TFOS Lifestyle: Impact of the digital environment on the ocular surface

Eye strain when performing tasks reliant on a digital environment can cause discomfort, affecting productivity and quality of life. Digital eye strain (the preferred terminology) was defined as "the development or exacerbation of recurrent ocular symptoms and/or signs related specifically to digital device screen viewing". Digital eye strain prevalence of up to 97% has been reported, due to no previously agreed definition/diagnostic criteria and limitations of current questionnaires which fail to differentiate such symptoms from those arising from non-digital tasks. Objective signs such as blink rate or critical flicker frequency changes are not 'diagnostic' of digital eye strain nor validated as sensitive. The mechanisms attributed to ocular surface disease exacerbation are mainly reduced blink rate and completeness, partial/uncorrected refractive error and/or underlying binocular vision anomalies, together with the cognitive demand of the task and differences in position, size, brightness and glare compared to an equivalent non-digital task. In general, interventions are not well established; patients experiencing digital eye strain should be provided with a full refractive correction for the appropriate working distances. Improving blinking, optimizing the work environment and encouraging regular breaks may help. Based on current, best evidence, blue-light blocking interventions do not appear to be an effective management strategy. More and larger clinical trials are needed to assess artificial tear effectiveness for relieving digital eye strain, particularly comparing different constituents; a systematic review within the report identified use of secretagogues and warm compress/humidity goggles/ambient humidifiers as promising strategies, along with nutritional supplementation (such as omega-3 fatty acid supplementation and berry extracts).

Analysis of the Outcomes of the Screen-Time Reduction in Computer Vision Syndrome: A Cohort Comparative Study

Purpose

To analyze the outcomes of screen-time reduction on the foveal responses that associates computer vision syndrome (CVS) using multifocal electroretinogram (mfERG) examination.

Methods

This prospective multicenter cohort comparative study included 49 eyes of 49 medical students divided into two groups. Group A (control group) included 25 eyes with no CVS diagnosis while group B (CVS group) included 24 eyes with CVS diagnosis. All students responded to the valid and reliable CVS-Form 3 (CVS-F3) questionnaire and underwent complete ophthalmic and mfERG examinations twice at the time recruitment in the study and four weeks after strict reduction of the daily screen-hours to ≤1 screen-hour daily to document associated foveal responses.

Results

We documented statistically significant reduction in foveal responses in CVS versus control groups in mean mfERG Rings 1, 2, and 5 with Quadrants 1, 2, and 4 (P=<0.0001, 0.0001, 0.0003, 0.001, 0.002, and 0.006, respectively). Following the screen-time reduction, the second mfERG examination revealed significant post-reduction improvements in foveal responses in CVS group particularly in mean mfERG Rings 1, 2, 3, and 5 with Quadrants 1 and 4 (P=<0.0001, <0.0001, 0.0005, 0.02, <0.0001, and 0.04, respectively).

Conclusion

This study documented the screen-induced foveal dysfunction that associates CVS using mfERG examination, which revealed remarkable significant improvements in foveal responses in the 4 weeks following strict screen-time reduction. These improvements were also associated with corresponding improvements in the visual performances. We suggest that the potential screen-induced foveal dysfunction outcomes might be reversible with strict screen-time reduction. We also recommend that educational institutional policies should limit online education-hours and redesign the mandated computer system use program to guard against visual sequelae of CVS.

Clinical Trials Registration

ClinicalTrials.gov (ID: NCT04405648).