Nearwork-induced transient myopia (NITM) and permanent myopia--is there a link?

Protocol for a parallel assignment prospective, randomised, double-blinded, placebo-controlled trial to evaluate the efficacy of 0.01% atropine for near work-induced transient myopia and myopic progression in China

INTRODUCTION

Assessment of near work-induced transient myopia (NITM) is important for permanent myopia development and progression. Atropine eye drop has been reported to be beneficial in reducing initial NITM and slowing down myopic progression. This study aimed to investigate the efficacy of 0.01% atropine in treating NITM and its possible association with the progression of refractive change in Chinese myopic children.

METHODS AND ANALYSIS

The study is designed as a parallel assignment prospective, randomised, double-blinded, placebo-controlled trial conducted at He Eye Specialist Hospital in Shenyang, China. One hundred fifty participants will be randomly assigned in a 1:1 ratio to receive 0.01% atropine or placebo eye drop once nightly bilaterally for 1 year. Initial NITM, cycloplegic refraction, axial length, best-corrected visual acuity, intraocular pressure and pupil diameter will be measured at baseline, 4 weeks, 12 weeks, 24 weeks, 36 weeks and 48 weeks. Visual Function Questionnaire will be administered at baseline and each follow-up visit. Adverse events also will be monitored and documented at each subsequent follow-up visit.

ETHICS AND DISSEMINATION

A parallel assignment prospective, randomised, double-blinded, placebo-controlled trial to evaluate the efficacy of 0.01% atropine for near work-induced transient myopia and myopic progression registered on 10 September 2023. Ethics approval number: IRB (2023) K025.01. The study's findings will be shared regardless of the effect's direction.

TRIAL REGISTRATION NUMBER

NCT06034366.

Analysis of 2-year spherical equivalent progression in emmetropic children with non-cycloplegic refraction: a retrospective chart review

BACKGROUND

We aimed to investigate children with an emmetropic non-cycloplegic refraction (NCR) to compare the difference in progression of NC spherical equivalent (SE) over 2 years between the children with emmetropic and hyperopic cycloplegic refraction (CR) values.

METHODS

Through a retrospective medical record review, 59 children aged under 10 years were evaluated. Refractive error was calculated as the average of the SE values of both eyes. According to the CR results, children with emmetropia (-0.50 to 1.00 diopter [D]) were assigned to group 1 (n = 29), and those with hyperopia (≥ 1.00 D) were assigned to group 2 (n = 30). The prevalence of myopia and SE progression were compared over 2 years. Correlations between final SE progression and baseline age and refractive error were analyzed and multiple regression analysis was conducted. Receiver operating characteristic curves that achieved the best cutoff points to distinguish between the groups were calculated.

RESULTS

Group 1 showed significantly myopic SE changes compared to baseline at the 1-year follow-up, and group 1 was significantly myopic compared with group 2 at the 2-year follow-up. Myopia prevalence was 51.7% in group 1 and 6.7% in group 2 after 1 year, and 61.1% and 16.7% after 2 years, respectively. In the correlation analysis, baseline age, baseline CR, and difference between CR and NCR showed significant correlations with the 2-year SE progression (r = -0.359, p = 0.005; r = 0.450, p < 0.001; r = -0.562, p < 0.001, respectively). However, NCR refractive error showed no significant correlation (r = -0.097, p = 0.468). In multiple regression analysis, baseline age (β= -0.082), and CR-NCR difference (β= -0.214) showed a significant effect on SE progression for 2 years. When an NCR value of 0.20 D was set as the cut-off value to distinguish between the groups, a sensitivity of 70% and specificity of 92% were obtained.

CONCLUSION

Even if NCR showed emmetropia, children with baseline CR values of emmetropia showed greater SE progression compared with those with hyperopia. Cycloplegia is essential to confirm the correct refractive status in children. It may be useful for predicting prognosis of SE progression.

The effect of atropine 0.01% eyedrops on relative peripheral refraction in myopic children

BACKGROUND

Relative peripheral refraction (RPR) is a significant factor that participates in myopic development. Here, we evaluated the effects of atropine 0.01% eyedrops, as an antimyopia drug, on RPR.

METHODS

Seventy-three children were enrolled from a randomized, double-blinded, placebo-0.01% atropine eyedrops cross-over trial. The study group had used the placebo for one year and then crossed over to atropine 0.01% eyedrops for half a year. The control group had used 0.01% atropine for one year and then crossed over to placebo eyedrops for half a year. Central and horizontal peripheral refractions (15° and 30° at the temporal and nasal retina) were measured under non-cycloplegia and cycloplegia.

RESULTS

No significant differences in age, gender, and central refraction were identified between the two groups (P > 0.05). Under non-cycloplegia, the control group showed significant relative hyperopia in the temporal 30° retina and the nasal retina (P = 0.031; P < 0.001; P < 0.001). In the study group, the relative hyperopia in the temporal 30° retina disappeared (P = 0.983). After cycloplegia, the control group had less myopia in central refractions and less hyperopia in temporal RPR (P < 0.001; P = 0.039; P < 0.001). The study group did not present significant changes in central refractions and temporal RPR (P = 0.122; P = 0.222; P = 0.475).

CONCLUSIONS

For myopic children, atropine 0.01% eyedrops can alleviate relative hyperopia in the temporal retina and the hyperopic shift before cycloplegia. The effect might participate in myopia control.

A comparative study of the prevalence of myopia and behavioral changes in primary school students

Objective

To analyze the changes in the prevalence of myopia and its relation to ocular biological parameters, and behaviors among primary school students in China, and understand the prevention and control of myopia.

Methods

Cross-sectional surveys were performed on 7–9-year-old children in the yrs. 2012 and 2019. In addition, spherical equivalent refraction (SER), axial length (AL), and AL/corneal radius ratio (AL/CR ratio) were collected without cycloplegia. Participants completed detailed questionnaires on behavior related to myopia.

Results

Data was collected on 623 children (8.02 ± 0.57 years old) in 2012 and 536 students in 2019 (8.09 ± 0.65 years old). The prevalence of myopia was 37.7% in 2012 and 39.9% in 2019. The SER was -0.25 (0.92) D in 2012 and -0.25 (1.25) in 2019. There was no statistical difference in the prevalence of myopia and SER over the 7 years (all P > 0.05). In 2019, the prevalence of myopia among girls demonstrated an increasing trend (33.8% vs. 37.8%), but there was no statistical difference (P > 0.05). The mean AL and AL/CR ratio of boys were decreasing (all P < 0.05). The proportion of children reading more than 2 h and using digital devices for more than 2 h per day after their classes in the 2019 group both decreased (all P < 0.05). However, the proportion of activities performed outdoors for more than 2 h./day decreased significantly (P = 0.001).

Conclusion

Compared with 2012, the prevalence of myopia in primary school students in 2019 was under control, which may be related to the improvement of children's near-work behavior, but there was the problem of insufficient outdoor activity time. In terms of ocular biological parameters, the risk of myopia for boys in 2019 was lower.

A Review of Intraocular Pressure (IOP) and Axial Myopia

The pathogenesis of myopia is driven by genetic and environmental risk factors. Accommodation not only alters the curvature and shape of the lens but also involves contraction of the ciliary and extraocular muscles, which influences intraocular pressure (IOP). Scleral matrix remodeling has been shown to contribute to the biomechanical susceptibility of the sclera to accommodation-induced IOP fluctuations, resulting in reduced scleral thickness, axial length (AL) elongation, and axial myopia. The rise in IOP can increase the burden of scleral stretching and cause axial lengthening. Although the accommodation and IOP hypotheses were proposed long ago, they have not been validated. This review provides a brief and updated overview on studies investigating the potential role of accommodation and IOP in myopia progression.

The impact of the COVID-19 pandemic, online-learning on the state of visual system and psychological state of students

The aim of this study: to identify and analyze changes in the lifestyle and psychological sphere of students who are undergoing online training in quarantine isolation due to the COVID-19 pandemic. Material and methods: 160 students were examined for the myopic refraction using the Duochrome Test, as well as shifts in the quality of vision as a result of online learning. All participants were also interviewed to ascertain living conditions and psychological status during domestic learning related to COVID-19 isolation. Result: it was found that 42.5 % participants have myopia, most of them students of 1 and 4 courses (26.5 % and 30.9 %, respectively). 85.6 % respondents noted deterioration in health after long-term visual work with personal computer and/or smartphone. The leading symptoms associated with work on digital displays were: decreased visual acuity and binocular vision disorders (81.9 %), headache (75.6 %), back muscle pain (71.9 %), eyes redness (55.6 %), dry and itchy eyes (45 % of respondents). It has been established what 75.6 % respondents indicated deterioration in their psychological condition as a result of quarantine restrictions: 68.1 % – stress, 48.8 % – emotional instability (irritability), 51.9 % – sleep disorders (insomnia), 16.3 % – depression. It is determined that daily average working time in the conditions of domestic online learning was 6.4±2.6 hours (compared to 4.1±1.7 hours in the pre-quarantine period). Conclusion: revealed deterioration in the quality of vision, general well-being and the psychological sphere of students who are undergoing online quarantine training due to the COVID-19 pandemic.

Impact of dual-focus soft contact lens wear on near work-induced transient myopia

CLINICAL RELEVANCE

Dual-focus soft contact lenses are effective in slowing myopia progression; however, their influence on near work-induced transient myopia (NITM) remains unknown. When performing a 5-min near task at 20 cm, we observed that dual-focus soft contact lens wear induced greater lags of accommodation and a lower initial NITM than single-vision soft contact lenses, which provides relevant information for better understanding the impact of using this optical design on the accommodative function.

BACKGROUND

NITM has been proposed as a myogenic factor, although it is a matter of debate by the scientific community. The main objective of this study was to assess the short-term effect of wearing dual-focus soft contact lenses for myopia control on the steady-state accommodative response and NITM.

METHODS

Twenty-four young myope adults wore, on two different days, dual-focus and single-vision soft contact lenses, while the accommodative response was dynamically measured with an open-field autorefractor during the execution of the NITM task. The shift and the time required to recover baseline levels in the refractive state after performing the 5-min near task (20 cm) were the main dependent variables.

RESULTS

We found a lower magnitude of accommodation during the execution of the near task with the dual-focus in comparison to the single-vision soft contact lenses (p < 0.001). There was a lower initial NITM with the dual-focus when compared to the single-vision lenses (corrected p-value = 0.003, Cohen's d = 0.68), but no statistically significant differences were observed for decay duration (p = 0.984).

CONCLUSIONS

Dual-focus soft contact lens wear causes a reduced accommodative response during a near task, and an initial small myopic shift at distance after a 5-min period of near viewing. The current findings may help to understand the mechanisms involved in myopia control with this optical strategy.

Greater axial elongation associated with low accommodative lag: new insights on accommodative lag theory for myopia

PURPOSE

We aimed to test the accommodative lag and mechanical tension theories for myopia by assessing the influence of the lag of accommodation on axial elongation by using three different near targets that are known to influence the accommodative response differently.

METHODS

Forty-two young adults were recruited for the study. Axial length was measured using a non-contact biometer, before and immediately after a 15 minute visual task, with one of the three near targets placed 20 cm from the eye: reading text from a paper, reading text from a smartphone and watching a video on a smartphone. The accommodative response was determined using an open-field autorefractor while the participants viewed the near target monocularly.

RESULTS

Lag of accommodation was significantly different for the three tasks: watching a video (mean ± standard error of the mean [SEM] 0.92 ± 0.10 D); reading text on the smartphone (0.59 ± 0.08 D); and reading text on paper (0.24 ± 0.09 D). There was a significant (p < 0.05) increase in axial length after reading text from a paper (10.5 ± 1.9 µm after 15-min) and reading text from a smartphone (5.2 ± 2.7 µm), but not after watching a video on a smartphone (-0.5 ± 1.7 µm, p = 0.47). Vitreous chamber depth increased significantly more with the reading tasks compared with watching a video (reading text from a paper and smartphone: 33.9 ± 4 µm and 31.7 ± 4 µm vs. watching a video on a smartphone: 14.6 ± 5 µm, p = 0.001).

CONCLUSION

Greater changes in axial length associated with the low lag of accommodation failed to support the theory that lag of accommodation during visual tasks could be the trigger for axial elongation. Reading on paper and smartphone at the closest reading distance may stimulate high accommodative demand and axial elongation as a consequence, possibly due to increased "ciliary muscle tension" during accommodation.

IMI Accommodation and Binocular Vision in Myopia Development and Progression

The role of accommodation in myopia development and progression has been debated for decades. More recently, the understanding of the mechanisms involved in accommodation and the consequent alterations in ocular parameters has expanded. This International Myopia Institute white paper reviews the variations in ocular parameters that occur with accommodation and the mechanisms involved in accommodation and myopia development and progression. Convergence is synergistically linked with accommodation and the impact of this on myopia has also been critiqued. Specific topics reviewed included accommodation and myopia, role of spatial frequency, and contrast of the task of objects in the near environment, color cues to accommodation, lag of accommodation, accommodative-convergence ratio, and near phoria status. Aspects of retinal blur from the lag of accommodation, the impact of spatial frequency at near and a short working distance may all be implicated in myopia development and progression. The response of the ciliary body and its links with changes in the choroid remain to be explored. Further research is critical to understanding the factors underlying accommodative and binocular mechanisms for myopia development and its progression and to guide recommendations for targeted interventions to slow myopia progression.

Effect of reading with a mobile phone and text on accommodation in young adults

Purpose

To investigate the effects of reading with mobile phone versus text on accommodation accuracy and near work-induced transient myopia (NITM) and its subsequent decay during near reading in young adults with mild to moderate myopia.

Methods

The refractions of 31 young adults were measured with an open-field autorefractor (WAM-5500, Grand Seiko) for two reading tasks with a mobile phone and text at 33 cm. The mean age of the young adults was 24.35 ± 1.80 years. The baseline refractive aspects were determined clinically with full distance refractive correction in place. The initial NITM and its decay time and accommodative lag were assessed objectively immediately after binocularly viewing a mobile phone or text for 40 min.

Results

The mean ± standard deviation (SD) initial NITM magnitude was greater for reading with text (0.23 ± 0.26 D) than for reading with mobile phone (0.12 ± 0.17 D), but there was no significant difference between the two reading tasks (p = 0.082). The decay time (median, first quartile, and third quartile) was 60 s (16, 154) and 70 s (32, 180) in the phone task and text task groups, respectively. There was also no significant difference in the decay time between the two reading types in general (p = 0.294). The accommodative lags of text tasks and mobile phones tasks were equivalent (1.27 ± 0.52 D vs 1.31 ± 0.64 D, p = 0.792).

Conclusion

There were no significant differences in accommodative lags and the initial NITM and its decay time between reading with a mobile phone and text in young adults.

Occupational health issues experienced by UK embryologists: informing improvements in clinical reproductive science practice

A consultation exercise was undertaken with UK embryologists to construct knowledge of the occupational health issues they experience in everyday practice. Data were obtained from 223 eligible survey responses. Work-related ill health was self-reported by 58.3% of respondents, 76.2% of whom reported multiple issues. The most frequently disclosed ill-health conditions were musculoskeletal disorders (45.3%) and stress and mental health problems (27.8%). Other issues with an incidence above 3% were ocular and auditory problems and needlestick and liquid nitrogen injuries. Shoulder injury or pain correspondingly increased in incidence with length of time in service. Absence from work and/or light duties were necessitated for 34.5% of those affected. Assessment of the evidence base for these work-related ill-health conditions explored contributory and ameliorating factors, which enabled a series of evidence-based recommendations to be formulated via the adoption of a GRADE-based framework.

The association between nearwork-induced transient myopia and progression of refractive error: A 3-year cohort report from Beijing Myopia Progression Study

PURPOSE

To investigate the natural change of nearwork-induced transient myopia (NITM), and its association with the progression of refractive error.

METHODS

Students of the Beijing Myopia Progression Study were examined at baseline and follow-up examinations, which included cycloplegic autorefraction. Initial NITM and its decay were assessed objectively immediately after binocularly-viewing and performing a sustained 5-minute near task (20 cm).

RESULTS

There were 223 students with both NITM and cycloplegic refractive data enrolled. There were 142 myopic (63.7%), 32 emmetropic (14.4%), and 49 hyperopic (22.0%) students according to their baseline cycloplegic refraction. The annual refractive change was -0.45 (-0.73, -0.21) D. From the baseline to the one-year and two-year follow-up periods, the initial NITM (median) increased significantly in the myopic students (0.16, 0.21, and 0.20D, p = 0.01, respectively). The overall proportion of NITM decay types shifted significantly from none being induced at baseline (non-induced: 17.0%, complete decay 57.4%, incomplete decay 25.6%) to incomplete decay at the 2-year follow-up (non-induced: 6.7%, complete decay 65.0%, incomplete decay 28.3%, p = 0.01). For the hyperopic students, after adjusting for risk factors, for every 1 diopter increase in the initial NITM at baseline, there was approximately a -1.48 diopter more relative myopic refractive progression (p = 0.01). No significant association was found between refractive change and the NITM parameters for either the myopic or emmetropic students after adjusting for the same confounders. However, this relation was significant in the hyperopes (p = 0.01).

CONCLUSION

NITM was only found to be significantly associated with the progression of a myopic refractive shift among the hyperopes.

Effect of Ultra-high-definition Television on Ocular Surface and Fatigue

PURPOSE

To investigate the effects of watching ultra-high-definition television (UHD TV) on subjective ocular fatigue and objective ocular surface indices.

METHODS

A total of 76 volunteers were recruited for this study. Subjects watched UHD TV for 10 minutes at a viewing distance of 110 cm. Best-corrected visual acuity, refractive errors, tear break-up time, corneal staining grading, conjunctival redness grading by slit-lamp examination, tear meniscus measurement by anterior segment optical coherence tomography, and ocular symptom scores were obtained before and immediately after watching UHD TV. Subgroup analyses were conducted according to participant age (old age group &gt;50 years vs. young age group ≤50 years) and dry-eye syndrome (presence vs. absence). The relationship between subjective and objective indices was evaluated.

RESULTS

The mean age of subjects was 39.6 ± 12.4 years. Watching UHD TV induced a decrease in tear break-up time in the non-dry-eye group (p &lt; 0.001) but not in the dry-eye group (p = 0.726). Corneal staining grades increased in all subgroups, and the changes were particularly larger in the older group (p = 0.038). The increase in ocular symptom scores was larger in the dry-eye group (p = 0.08) and in the older group (p = 0.016). The decrease in tear break-up time and ocular symptom scores after watching UHD TV was significantly correlated with tear break-up time.

CONCLUSIONS

Tear break-up time significantly decreased in non-dry-eye subjects after watching UHD TV. Subjective ocular discomfort increased significantly in subjects over the age of 50 and in participants with dry-eye syndrome.

Factors associated with myopia in Korean children: Korea National Health and nutrition examination survey 2016-2017 (KNHANES VII)

BACKGROUND

To evaluate the prevalence and risk factors associated with myopia and high myopia in children in South Korea.

METHODS

A total of 983 children 5-18 years of age who participated in the Korean National Health and Nutrition Examination Survey 2016-2017 (KNHANES VII), a nationwide population-based cross-sectional study, were evaluated. Myopia and high myopia were defined as a spherical equivalent (SE) ≤ - 0.5 diopters (D) and SE ≤ --6.0 D. The association between refractive errors and potential risk factors for myopia was analyzed.

RESULTS

The prevalence of myopia and high myopia was 65.4 and 6.9%, respectively. Older age and parental myopia were significantly associated with both myopia and high myopia, while higher body mass index (BMI) was associated with high myopia only. Although the proportion of subjects who spent more time on near work activities (≥4 h/day) was sequentially increased with increased refractive error, this tendency was not statistically significant by multivariable logistic regression.

CONCLUSIONS

Korean children had a high prevalence of myopia and high myopia. In this age group, the risk of myopia increased with aging and parental myopia. Higher BMI may be associated with high myopia.

Use of Topical 0.01% Atropine for Controlling Near Work-Induced Transient Myopia: A Randomized, Double-Masked, Placebo-Controlled Study

Purpose: To investigate the efficacy and safety of topical low-concentration (0.01%) atropine for controlling near work-induced transient myopia (NITM) in a young Chinese population. Methods: This was a randomized, double-blinded, placebo-controlled study. The participants were randomly divided into the 0.5% hydroxypropyl-methylcellulose-treated group (control group) or 0.01% atropine-treated group (study group). Participants' pulse rate, respiration rate, intraocular pressure, pupil diameter, and magnitude of initial NITM were evaluated at baseline and on day 7 and 14 during treatment. In addition, ocular discomfort and adverse effects were recorded. Results: Of the initial 176 participants, 145 (82.4%) completed the 14-day treatment and all evaluations. At baseline, no difference in the magnitude of initial NITM was observed between the control and study groups (P = 0.826). However, the magnitude of initial NITM of the study group was significantly lower at both day 7 (-0.11 ± 0.227 D) and day 14 (0.076 ± 0.183 D) after treatment initiation, compared with the magnitude of initial NITM in the control group (P < 0.001). No serious complications were observed. However, significantly larger pupil diameters were noted on day 7 and 14 in the study group than in the control group (P < 0.001). Conclusions: We speculate that daily topical 0.01% atropine application effectively reduced the magnitude of initial NITM, without any serious complications. The minimal pupil dilation induced by the treatment was acceptable. Low-concentration atropine may be useful in clinical settings as treatment for young patients with NITM.

Objective User Visual Experience Evaluation When Working with Virtual Pixel-Based 3D System and Real Voxel-Based 3D System

Volumetric display shows promising implications for healthcare related applications as an innovative technology that creates real three-dimensional (3D) image by illuminating points in three-dimensional space to generate volumetric images without image separation. We used eccentric photorefractometry to objectively study ocular performance in a practical environment by evaluating near work-induced refraction shift, accommodative microfluctuations, and pupil size for 38 young adults after viewing anaglyph, and volumetric 3D content for prolonged time. The results of our study demonstrate that participants who performed relative depth estimation task on volumetric 3D content were less likely to experience task-induced myopic refraction shift. For both 3D content types, we observed pupil constriction, that is possibly related to visual fatigue. For anaglyph 3D pupil constriction, onset was observed significantly sooner, compared to volumetric 3D. Overall, sustained work with 3D content, and small disparities or the fully eliminated possibility of accommodation-vergence conflict, not only minimizes near work-induced myopic shift, but also provide beneficial accommodation relaxation that was demonstrated in this study as hypermetropic shift for nearly half of participants.

Effects of Progressive Addition Lens Wear on Digital Work in Pre-presbyopes

SIGNIFICANCE

Growing popularity of handheld digital devices imposes significant challenges to our visual system and clinical management. This study aimed to determine the effects of lens design on parameters that may influence the refractive management of pre-presbyopic adult computer users.

PURPOSE

To determine the effects of wearing conventional single-vision lenses (SVL) versus progressive addition lenses (PAL) on the working distance and refractive status.

METHODS

Adult computer users, recruited from two age cohorts (18 to 25 years, n = 19; 30 to 40 years, n = 45), were prescribed SVLs and PALs designed for use with handheld digital devices. For each lens type, the working distance and refractive shift (post-task − pre-task) were measured immediately after lens delivery (T0) and after 1 month of lens wear (T1). Working distances were recorded with an automatic ultrasound device while the participants were playing a video game. Refractive status through the subjects' glasses was measured before (pre-task) and after playing the game (post-task). Questionnaires assessing the frequencies of 10 digital work–related visual symptoms were conducted for both lens types at T1.

RESULTS

Switching from SVL to PAL increased the working distance in both cohorts (mean ± SEM = 1.88 ± 0.60 cm; P = .002) and induced a small but significant positive refractive shift (+0.08 ± 0.04 D, P = .021) in the older cohort at T1. In the younger cohort, the changes in working distance due to the switching lens design were correlated with myopic error (r = +0.66, P = .002). In the older cohort, the changes in refractive shift due to switching lens design were correlated with amplitude of accommodation at both time points (r for T0 and T1 = −0.32 and −0.30, respectively; both P < .05). Progressive addition lens was rated as causing less “increased sensitivity to light” compared with SVL.

CONCLUSIONS

Switching from SVL to PAL increased the working distance and induced a positive refractive shift in the majority of pre-presbyopic adults.

Emmetropes and myopes differ little in their accommodation dynamics but strongly in their ciliary muscle morphology

Previous work suggested an association between near vision and myopia. We therefore investigated the accommodation process in emmetropes and myopes regarding morphologic changes of the ciliary muscle (CM) and power changes of the lens for different accommodation demands. The temporal CM of 18 emmetropic and 20 myopic students was imaged via anterior segment optical coherence tomography during far and near accommodation (2.5D, 3D, 4D). Additionally, accommodation dynamics to the stimuli pattern far-near-far (15 s each; 2.5D, 3D, 4D) were recorded with eccentric infrared photorefraction. OCT images were processed using custom-developed software facilitating the analysis of selective CM thickness (CMT) readings and CMT profiles. Anterior CMT readings were significantly smaller in myopes. Starting at 1.4 mm posterior to the scleral spur (SP), myopic CM became thicker than emmetropic. Anterior CMT changes (ΔCMT) continuously increased with accommodation demand in myopes while emmetropic ΔCMT only increased from 2.5D to 3D. Compared to emmetropes, myopes showed smaller ΔCMT but increased CM movement relative to SP. There were no significant differences between the groups for accommodation changes from far to near vision and vice versa, velocity, microfluctuations, power spectra or lag of accommodation. At 4 D, larger ΔCMT were associated with lower lens changes for disaccommodation. While CM shape, movement, and thickness showed distinct differences depending on refractive error, emmetropes and myopes did not differ in their dynamic accommodation. Further analysis is necessary to evaluate whether the CM's anatomical shape or predispositions in its intramuscular constituents are causative factors in myopigenesis.

Prolonged nearwork affects the ciliary muscle morphology

There is evidence for a possible link between myopia development and near vision. We investigated the effect of prolonged nearwork on ciliary muscle (CM) morphology and accommodation in 18 myopic and 17 emmetropic subjects (age 19 to 25). The CM was imaged during far (0.25 D) and near vision (4 D) using optical coherence tomography (OCT), and accommodation to a step pulse (0.25 D - 4 D - 0.25 D, 15 s each) was assessed by eccentric infrared photorefraction before and after a 30-min reading task at 25 cm. OCT images were analyzed using a custom-developed semi-automatic segmentation algorithm to determine CM thickness (CMT) profiles and selective CMT readings. Accommodation was assessed using a non-linear model. On average, the CM got thinner after nearwork, predominantly at 0.0-1.4 mm posterior to the scleral spur in emmetropes, and at 1.0-1.9 mm in myopes. Selective CMT readings confirmed a significant thinning after nearwork (univariate ANOVA F_1,66 = 26.313, p < 0.001), without any influence of the subjects' refractive state (F_1,66 = 1.887, p = 0.174) or the target distance (F_1,66 = 0.014, p = 0.907). The mean accommodation response for targets at infinity was significantly increased after nearwork (F_1,32 = 7.775, p = 0.009), with a larger myopic shift in myopes (F_1,32 = 11.310, p = 0.002). No change in velocity of accommodation was found. Sharing properties of striated muscles, the CM was expected to increase its thickness, but the opposite was found. Previous studies suggesting sustained nearwork to result in a CM spasm cannot be confirmed by the data presented here. Further research exploring the possible impact of sympathetic innervation is necessary as it is activated during intense nearwork.

The difference between cycloplegic and non-cycloplegic autorefraction and its association with progression of refractive error in Beijing urban children

PURPOSE

To investigate the difference between cycloplegic and non-cycloplegic autorefraction and its association with the progression of refractive error in Beijing urban children.

METHODS

A total of 386 children aged 6-17 years were enrolled in the baseline investigation of the Beijing Myopia Progression Study in 2010. They were invited for follow-up vision examinations in the years 2011, 2012, and 2013, including cycloplegic (cyclopentolate 1%, three times) autorefraction. We investigated the difference between the cycloplegic spherical equivalent (SE) and the non-cycloplegic SE (DSE) provided by autorefraction and its association with refractive error progression. The progression of refractive error was defined as the difference between the cycloplegic SE at follow-up and at baseline.

RESULTS

Two hundred and nineteen children (57%) with completed refractive data (mean ± standard deviation: -1.36 ± 2.44 D at baseline) were ultimately enrolled. The DSE reduced from 0.51 ± 0.72 D at baseline to 0.19 ± 0.43 D in the third year of follow-up (p = 0.01). The baseline DSE was positively associated with the children's baseline cycloplegic refraction (β = 0.193 dioptre dioptre^-1 , p < 0.001). After further divided by refractive status, the DSE was consistently higher in the hyperopic group than in either the emmetropic or myopic groups at each follow-up (all p < 0.001). In the multivariate regression analysis, the myopic children with larger baseline DSE (β = -0.404 dioptre dioptre^-1 , p = 0.01) exhibited more myopic refractive change. However, baseline DSE was not found to be a significant risk factor (relative risk, 95% confidence interval: 1.06, 0.79-1.41) for those with newly developed myopia.

CONCLUSION

In this sample, the children's DSE was found to be increased as the hyperopic refraction increased. Furthermore, greater the DSE was associated with the progression of refractive error among the myopic children, but not with the onset of myopia.

Factors Associated with Visual Fatigue from Curved Monitor Use: A Prospective Study of Healthy Subjects

Purpose

To investigate the factors associated with visual fatigue using monitors with various radii of curvature.

Methods

Twenty normal healthy adults (8 men, 12 women; mean age, 26.2 ± 2.5 years) prospectively watched five types of monitors including flat, 4000R, 3000R, 2000R, and 1000R curved monitors for 30 min. An experienced examiner measured the ophthalmological factors including near point of accommodation (NPA), near point of convergence (NPC), refraction, parameters during pupil response at light and saccadic movement just before and after the visual tasks. The questionnaires about subjective ocular symptoms were also investigated just before and after the visual tasks.

Results

The NPA increased after the visual tasks with a flat monitor compared with the curved monitors, with the 1000R curved monitor showing the smallest change (p = 0.020). The NPC increased for every monitor after the visual tasks; the largest increase occurred with the flat monitor (p = 0.001). There was no difference in refractive error, pupil response, or saccadic movement in the comparison of before and after the visual tasks. Among the nine factors in the questionnaire, the score of “eye pain” was significantly higher for the flat monitor versus the 1000R curved monitor after the visual tasks (p = 0.034).

Conclusions

We identified NPA, NPC, and eye pain as factors associated with visual fatigue. Also, the curvature of the monitor was related to the visual fatigue.

Ocular Outcomes Comparison Between 14- and 70-Day Head-Down-Tilt Bed Rest

Purpose

To compare ocular outcomes in healthy subjects undergoing 14- and/or 70-day head-down-tilt (HDT) bed rest (BR).

Methods

Participants were selected by using NASA standard screening procedures. Standardized NASA BR conditions were implemented. Subjects maintained a 6° HDT position for 14 and/or 70 consecutive days. Weekly ophthalmologic examinations were performed in the sitting (pre/post-BR only) and HDT positions. Mixed-effects linear models compared pre- and post-HDT BR observations between 14- and 70-day HDT BR in best-corrected visual acuity, spherical equivalent, intraocular pressure (IOP), Spectralis OCT retinal nerve fiber layer thickness, peripapillary and macular retinal thicknesses.

Results

Sixteen and six subjects completed the 14- and 70-day HDT BR studies, respectively. The magnitude of HDT BR–induced changes was not significantly different between the two studies for all outcomes, except the superior (mean pre/post difference of 14- vs. 70-day HDT BR: +4.69 μm versus +11.50 μm), nasal (+4.63 μm versus +11.46 μm), and inferior (+4.34 μm versus +10.08 μm) peripapillary retinal thickness. A +1.42 mm Hg and a +1.79 mm Hg iCare IOP increase from baseline occurred during 14- and 70-day HDT BR, respectively. Modified Amsler grid, red dot test, confrontational visual field, color vision, and stereoscopic fundus photography were unremarkable.

Conclusions

Seventy-day HDT BR induced greater peripapillary retinal thickening than 14-day HDT BR, suggesting that time may affect the amount of optic disc swelling. Spectralis OCT detected retinal nerve fiber layer thickening post BR, without clinical signs of optic disc edema. A small IOP increase during BR subsided post HDT BR. Such changes may have resulted from BR-induced cephalad fluids shift. The HDT BR duration may be critical for replicating microgravity-related ophthalmologic changes observed in astronauts on ≥6-month spaceflights.

Eye growth and myopia development: Unifying theory and Matlab model

The aim of this article is to present an updated unifying theory of the mechanisms underlying eye growth and myopia development. A series of model simulation programs were developed to illustrate the mechanism of eye growth regulation and myopia development. Two fundamental processes are presumed to govern the relationship between physiological optics and eye growth: genetically pre-programmed signaling and blur feedback. Cornea/lens is considered to have only a genetically pre-programmed component, whereas eye growth is considered to have both a genetically pre-programmed and a blur feedback component. Moreover, based on the Incremental Retinal-Defocus Theory (IRDT), the rate of change of blur size provides the direction for blur-driven regulation. The various factors affecting eye growth are shown in 5 simulations: (1 - unregulated eye growth): blur feedback is rendered ineffective, as in the case of form deprivation, so there is only genetically pre-programmed eye growth, generally resulting in myopia; (2 - regulated eye growth): blur feedback regulation demonstrates the emmetropization process, with abnormally excessive or reduced eye growth leading to myopia and hyperopia, respectively; (3 - repeated near-far viewing): simulation of large-to-small change in blur size as seen in the accommodative stimulus/response function, and via IRDT as well as nearwork-induced transient myopia (NITM), leading to the development of myopia; (4 - neurochemical bulk flow and diffusion): release of dopamine from the inner plexiform layer of the retina, and the subsequent diffusion and relay of neurochemical cascade show that a decrease in dopamine results in a reduction of proteoglycan synthesis rate, which leads to myopia; (5 - Simulink model): model of genetically pre-programmed signaling and blur feedback components that allows for different input functions to simulate experimental manipulations that result in hyperopia, emmetropia, and myopia. These model simulation programs (available upon request) can provide a useful tutorial for the general scientist and serve as a quantitative tool for researchers in eye growth and myopia.

Near work-induced transient myopia in Indian subjects

PURPOSE

The aim was to determine the characteristics of near work-induced transient myopia (NITM) in asymptomatic Indian subjects and the influence of target size and contrast.

METHODS

Two studies were conducted: First, 24 myopes and 24 emmetropes viewed four targets (N8 and N12 with 50 and 90 per cent contrasts) placed at 0.2 m for five minutes. The refractive status was assessed objectively, before and after carrying out the near task, with the Grand Seiko WAM-5500 open-field autorefractor under monocular viewing conditions. Second, a different group of 24 myopes and 24 emmetropes viewed a N12 target with 90 per cent contrast for 60 minutes with pre- and post-refractive state measurements repeated as above. NITM was defined as the difference between pre-task and post-task distance refraction.

RESULTS

In the first study, myopes demonstrated an initial post-task myopic shift of 0.21 D, whereas emmetropes demonstrated a small hyperopic shift of 0.07 D (p < 0.001). The myopes demonstrated a decay time constant of 6.07 seconds. There was no effect of target size or contrast on the magnitude of the NITM or the decay time constant (p > 0.05). In the second study, myopes showed a NITM of 0.31 D, which was significantly greater than emmetropes (p < 0.001). The myopes demonstrated a decay time constant of 8.16 seconds.

CONCLUSION

The magnitude of the NITM was higher in myopes compared to emmetropes for both five minute and 60 minute viewing time. The NITM decayed slightly faster than that found in previous literature for some other ethnic groups. Potential reasons for these findings are discussed.

The impact of computer use in myopia progression: a cohort study in Spain

OBJECTIVE

Many subjects, especially highly educated subjects, are increasingly exposed to computer use. This exposure might represent an explanation for the growing rates of myopia.

METHODS

We assessed 17,217 Spanish university graduates from the SUN project, an open-recruitment cohort. Their mean age was 38.5 years (SD 12.1), and their mean time of exposure to computers was 14.3h/week (SD 14.6). We estimated multivariable-adjusted odds ratios (OR) for the risk of myopia development and/or progression (≥0.5 diopters) according to baseline exposure to computer and to changes in exposure.

RESULTS

The age and sex-adjusted OR comparing >40 h/week of exposure versus<10h/week was 1.34 (95% confidence interval (CI): 1.12-1.60). This association remained essentially unchanged after additional adjustments. Comparing participants who increased their exposure to computers, versus those with no change, the age and sex-adjusted OR was 1.49 (1.34-1.66). This result was unchanged after additional adjustments.

CONCLUSIONS

To our knowledge this is the first large longitudinal assessment in young adults, showing that exposure to computer use is associated with myopia development or progression in a cohort of Spanish university graduates. Further studies are needed to confirm these epidemiological findings.

Progression of lower and higher-order aberrations: a longitudinal study

BACKGROUND

The aim of the present study was to investigate the effect of near-work on lower and higher-order aberrations, and its progression over a 9-month period during the school year.

METHODS

Data from 24 young-adult myopic eyes, and 24 non-myopic eyes were used in this investigation. The lower-order aberrations, coma, spherical aberration (SA), and total root mean square (RMS) of higher order aberrations (total HOA) were measured using an open-field iTrace aberrometer, at both the initial baseline evaluation, and then at the follow-up visits over a 9-month period. Pupil size of 4 mm was used for the aberration measurements.

RESULTS

The group mean (SD) of the subjects (mean age: 23.6 +/- 3.4 years) at the initial and follow-up visit was 0.47D (0.47D) and 0.31D (0.41D), in the non-myopes and -3.58D (2.08D) and -3.86D (2.14D) in the myopes, respectively. Significant increases in myopic refraction were observed. The group mean (SD) total HOA at the initial and final visit was 0.12 (0.08) and 0.11 (0.06) microns, in the non-myopes, and 0.15 (0.08) and 0.15 (0.08) microns, in the myopes, respectively. The group mean RMS of the coma at the initial and final visit was 0.06 (0.04) and 0.07 (0.05), in the non-myopes, and 0.08 (0.06) and 0.09 (0.06) microns, in the myopes, respectively. The group mean SA of the subjects at the initial and last visit was 0.04 (0.04) and 0.03 (0.03), in the non-myopes, and 0.04 (0.04) and 0.04 (0.04) microns, in the myopes, respectively.

CONCLUSIONS

There was a significant difference in myopic refraction, over the 9-month assessment period. However, no significant difference in total HOA, SA, and coma between the initial and follow-up visits in both the myopes and the non-myopes was observed.

Effect of watching 3-dimensional television on refractive error in children

Purpose

To investigate the effect of watching 3-dimensional (3D) television (TV) on refractive error in children.

Methods

Sixty healthy volunteers, aged 6 to 12 years, without any ocular abnormalities other than refractive error were recruited for this study. They watched 3D TV for 50 minutes at a viewing distance of 2.8 meters. The image disparity of the 3D contents was from -1 to 1 degree. Refractive errors were measured both before and immediately after watching TV and were rechecked after a 10-minute rest period. The refractive errors before and after watching TV were compared. The amount of refractive change was also compared between myopes and controls. The refractive error of the participants who showed a myopic shift immediately after watching TV were compared across each time point to assure that the myopic shift persisted after a 10-minute rest.

Results

The mean age of the participants was 9.23 ± 1.75 years. The baseline manifest refractive error was -1.70 ± 1.79 (-5.50 to +1.25) diopters. The refractive errors immediately after watching and after a 10-minute rest were -1.75 ± 1.85 and -1.69 ± 1.80 diopters, respectively, which were not different from the baseline values. Myopic participants (34 participants), whose spherical equivalent was worse than -0.75 diopters, also did not show any significant refractive change after watching 3D TV. A myopic shift was observed in 31 participants with a mean score of 0.29 ± 0.23 diopters, which resolved after a 10-minute rest.

Conclusions

Watching properly made 3D content on a 3D TV for 50 minutes with a 10-minute intermission at more than 2.8 meters of viewing distance did not affect the refractive error of children.

Association between video display terminal use and dry eye disease in school children

PURPOSE

To evaluate the risk factors of dry eye disease in school children associated with video display terminal use.

METHODS

Two-hundred eighty-eight children were classified in either a dry eye disease group or control group according to the diagnostic criteria of dry eye disease. The results of ocular examinations, including best-corrected visual acuity, slit-lamp examination, and tear break-up time, were compared between groups. The results of questionnaires concerning video display terminal use and ocular symptoms were also compared.

RESULTS

Twenty-eight children were included in the dry eye disease group and 260 children were included in the control group. Gender and best-corrected visual acuity were not significantly different between the two groups. Smartphone use was more common in the dry eye disease group (71%) than the control group (50%) (P = .036). The daily duration of smartphone use and total daily duration of video display terminal use were associated with increased risk of dry eye disease (P = .027 and .001, respectively), but the daily duration of computer and television use did not increase the risk of dry eye disease (P = .677 and .052, respectively).

CONCLUSIONS

The results showed that smartphone use is an important dry eye disease risk factor in children. Close observation and caution regarding video display terminal use, especially smartphones, are needed for children.

Nearwork-induced transient myopia (NITM) in anisometropia

OBJECTIVE

To assess the magnitude of nearwork-induced transient myopia (NITM) under binocular viewing conditions separately in each eye of individuals with mild to moderate anisometropia to determine the relationship between NITM and their interocular refractive error.

METHODS

Forty-three children and young adults with anisometropia [cycloplegic spherical equivalent (SE) difference >1.00 D] were tested (ages 9-28 years). NITM was measured with binocular viewing separately in each eye after binocularly performing a sustained near task (5 D) for 5 min incorporating a cognitive demand using an open-field, infrared autorefractor (Grand-Seiko, WAM-5500). Data were averaged over 10 s bins for 3 min in each eye. Initial NITM, its decay time (DT), and its decay area (DA) were determined. A-scan ultrasound ocular biometry was also performed to determine the axial length of each eye.

RESULTS

The more myopic eye exhibited increased initial NITM, DT, and DA as compared to the less myopic eye (0.21 ± 0.16 D vs 0.15 ± 0.13 D, p = 0.026; 108.4 ± 64.3 secs vs 87.0 ± 65.2 secs, p = 0.04; and 17.6 ± 18.7 D*secs vs 12.3 ± 15.7 D*secs, p = 0.064), respectively. The difference in DA and the difference in SE between the more versus less myopic eye were significantly correlated (r = 0.31, p = 0.044). Furthermore, 63% (27/43), 56% (24/43), and 70% (30/43) of the more myopic eyes exhibited increased initial NITM, longer DT, and larger DA, respectively, than found in the less myopic eye.

CONCLUSIONS

In approximately two-thirds of the anisometropic individuals, the initial NITM and its decay area were significantly increased in the more myopic eye as compared to the less myopic eye. NITM may play an important role in the development of interocular differences in myopia, although a causal relationship is yet to be established. Furthermore, the findings have potentially important implications regarding accommodative control and interocular accommodative responsitivity in anisometropia, in particular for anisomyopia.

Myopia prevention, near work, and visual acuity of college students: integrating the theory of planned behavior and self-determination theory

There has been little research examining the psychological antecedents of safety-oriented behavior aimed at reducing myopia risk. This study utilizes self-determination theory (SDT) and the theory of planned behavior (TPB) to understand the role of motivational and social-cognitive factors on individuals' near-work behavior. Adopting a prospective design, undergraduate students (n = 107) completed an initial questionnaire based on SDT in week 1, a second questionnaire containing measures of TPB variables in week 2, and objective measures of reading distance and visual acuity in week 6. The data were analyzed by variance-based structural equation modeling. The results showed that perceived autonomy support and autonomous motivation from SDT significantly predicted attitude, subjective norm, and perceived behavioral control from the TPB. These social-cognitive factors were significantly associated with intention and intention significantly predicted reading distance. The relationships in the model held when controlling for visual acuity. In conclusion, the integrated model of SDT and the TPB may help explain myopia-preventive behaviors.

Nearwork-induced changes in lenticular thickness in different refractive groups

PURPOSE

The aim of this study was to directly measure lenticular thickness and its additivity after 1 and 2 hours of continuous reading at near in myopic and emmetropic young adults.

METHODS

Thirty-five subjects consisting of 12 early-onset myopes, 11 late-onset myopes, and 12 emmetropes were tested. Axial lenticular thickness was measured in the right eye using A-scan ultrasonography before and immediately after 1 and 2 hours of continuous reading at near (35 to 40 cm).

RESULTS

Group mean (±SD) changes in lenticular thickness from baseline values after the first and second hours of reading were 0.025 ± 0.011 and 0.035 ± 0.017 mm, respectively. The group mean increase in lenticular thickness after the second hour was significantly larger than after the first hour, with subsequent subgroup analysis indicating that this was found in the myopes only.

CONCLUSION

The lenticular increase was additive in nature, but only in the late-onset and early-onset myopes. This confirmed and extended objectively earlier studies that suggested increased nearwork accommodative susceptibility of a primarily lenticular nature in myopes.

Bifocal lens control of myopic progression in children

Bifocal spectacle lenses have been used as a strategy to slow myopic progression in children since the 1950s and perhaps earlier. The reported success of this strategy varies greatly, as does the design of studies reporting the outcomes of their use-from earlier retrospective analysis of records to later prospective clinical trials. Collectively, published data support the suggestion that bifocal lenses inhibit myopic development in children but only by a small amount and only in a subset of children. Possible reasons for the greatly varying outcomes include a lack of individualism of the treatment and failure to take the vergence system into account. This review summarises the results of bifocal and multifocal studies, describes how accommodation, convergence and their interaction are linked to myopic development and details how a bifocal treatment that takes this into account may be devised. Also discussed is whether alterations to peripheral retinal blur contribute to bifocal lens effects.

Effect of nearwork-induced transient myopia on distance retinal defocus patterns

The purpose of the current study was to assess the effect of nearwork-induced transient myopia (NITM) on retinal defocus patterns during distance viewing. An empirically derived, conceptual model of human blur perception and related retinal defocus patterns has been extended to determine the effect of NITM on the relative contributions of myopic and hyperopic retinal defocus during distance viewing. Under the normal hyperfocal refractive condition during distance viewing with isolated stimulus conditions, there is very small myopic defocus (approximately 0.25 diopters), and no hyperopic defocus, present. After sustained nearwork generating NITM, a moderate increase in this myopic defocus contribution takes place. In the normal isolated distance viewing situation with only very small myopic defocus present, as would occur with many far outdoor activities, the paucity of overall retinal defocus may provide a "protected" condition against myopia development. In contrast, with the addition of NITM producing increased myopic retinal defocus only, there is an imbalance of retinal defocus that may be myopigenic, especially in the context of foveal and peripheral retinal interactions.