Nearwork-induced Transient Myopia Research Articles

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

IntroductionAssessment 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...

2.2: Invited Paper: The Effect of Tablet's Color Temperature on Ocular Health in Children

This study aims to evaluate the impact of the tablet's screen color temperature on children's eye health. A low color temperature (2800K) tablet and a high color temperature (8500K) tablet were used for 24 children to watch cartoon video. Before and after keeping watching video for 30 minutes, the children were evaluated in some ocular parameters, such as near-work induced transient myopia (NITM), accommodative lag, near point of convergence, accommodative amplitude et al., and an asthenopia questionnaire. Repeated analysis of variance was used to compare differences between two color temperature settings, before and after watching video, as well as to analyze the interaction. The mean NITM of children increased after using the high color temperature tablet, while the NITM change little after using the low color temperature tablet. After using the tablet for half an hour, the tear film break-up time was significantly shorter, but there was no significant difference between two color temperature settings. There was no difference in the total score of the visual fatigue questionnaire between the color temperatures settings after watching video. The item of burning sensation tended to score higher after watching the high color temperature tablet. The unusually high color temperature setting in tablet induced greater NITM and higher possibilities of ocular burning sensation in children even they only watched tablet screen for 30 minutes. Color temperature is a sensitive parameter for children's ocular health.

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

ABSTRACTClinical relevanceDual-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.BackgroundNITM 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.MethodsTwenty-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.ResultsWe 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).ConclusionsDual-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.

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

PurposeTo 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.MethodsThe 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.ResultsThe 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).ConclusionThere 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.

Commentary: Nearwork-induced transient myopia - Is this the game changer?

Commentary: Nearwork-induced transient myopia - Is this the game changer?

Preventive Effectiveness of Distant-Image Screen Display Toward Accommodative Lag and Nearwork-Induced Transient Myopia: A Self-Controlled Study

Preventive Effectiveness of Distant-Image Screen Display Toward Accommodative Lag and Nearwork-Induced Transient Myopia: A Self-Controlled Study

Nearwork-induced transient myopia and accommodation function before and after laser-assisted in situ keratomileusis surgery.

Purpose:To assess the change in Near Induced Transient Myopia (NITM) and other accommodation parameters, before and after undergoing LASIK surgery for myopia correction.Methods:Twenty-nine myopic subjects were recruited from a tertiary eye hospital in India. Age range was 21 to 35 years with an average age of 26.1 ± 3.5 years. Mean spherical equivalent was –3.86 D ± 1.50 D presurgery. NITM, lag of accommodation, near point of convergence (NPC), accommodative amplitude (AA), and binocular near accommodative facility (AF) were measured. All data were collected 21 days prior to and 30 days after LASIK surgery.Results:NITM, lag of accommodation and amplitude of accommodation were significantly lower (NITM -0.05 ± 0.15, Lag 0.38 ± 0.38, AA 10.27 ± 2.24) after surgery when compared to before (NITM 0.26 ± 0.12, Lag 0.77 ± 0.51, AA 12.18 ± 2.02; P < 0.001). Accommodative facility increased and near point of convergence was significantly more distal following surgery (AF 10.70 ± 2.29, NPC 7.96 ± 1.63) when compared to prior (AF 8.65 ± 2.74, NPC 5.62 ± 1.71; P < 0.001).Conclusion:Significant changes in NITM and accommodation function should be expected in the short term following LASIK surgery. This study supports the importance of evaluating accommodative parameters and patient counselling prior to and following refractive surgery.

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

PurposeTo investigate the natural change of nearwork-induced transient myopia (NITM), and its association with the progression of refractive error. MethodsStudents 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). ResultsThere 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). ConclusionNITM was only found to be significantly associated with the progression of a myopic refractive shift among the hyperopes.

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.

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

PurposeThe 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.MethodsTwo 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.ResultsIn 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.ConclusionThe 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.

Nearwork-Induced Transient Myopia and Parental Refractive Error

To investigate the relationship between parental refractive error and the nearwork-induced transient myopia (NITM) characteristics of their children. Three hundred sixty children (173 boys and 187 girls) aged 6 to 17 years were tested. Initial NITM and its decay time (DT) were assessed objectively (WAM-5500, Grand-Seiko) immediately after binocularly viewing and performing a sustained near task (5 diopters [D]) for 5 minutes, incorporating a cognitive demand with full distance refractive correction in place. The NITM was classified into three categories: low (< 0.15 D), moderate (0.15 to 0.30 D), or high (≥0.30 D), whereas its decay was classified into two categories, namely, complete or incomplete. In addition, the children were divided into three groups based on the number of myopic parents (none, one, or two) and into four groups based on the level of parental myopia (no, low, moderate, or high). Neither paternal nor maternal refractive error was associated with either their children's initial NITM magnitude or its DT in the myopic, emmetropic, or hyperopic groups or the combined group. No significant differences (p > 0.05) in the NITM magnitude, DT, or decay time constant were found as related to the number of myopic parents or level of parental myopia. Multiple odds ratio for incomplete decay of NITM did not change significantly (p > 0.05) with either an increase in number of myopic parents or level of parental myopia. There was no association between parental refractive error and their children's NITM characteristics. This suggests a primary environmental basis for the NITM characteristics in the children.

Nearwork‐induced transient myopia (NITM) in anisometropia

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. 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. 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. 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.

Children’s Accommodation During Reading of Chinese and English Texts

Inaccurate accommodation during nearwork and subsequent accommodative hysteresis may influence myopia development. Myopia is highly prevalent in Singapore; an untested theory is that Chinese children are prone to these accommodation characteristics. We measured the accuracy of accommodation responses during and nearwork-induced transient myopia (NITM) after periods spent reading Chinese and English texts. Refractions of 40 emmetropic and 43 myopic children were measured with a free-space autorefractor for four reading tasks of 10-minute durations: Chinese (SimSun, 10.5 points) and English (Times New Roman, 12 points) texts at 25 cm and 33 cm. Accuracy was obtained by subtracting accommodation response from accommodation demand. Nearwork-induced transient myopia was obtained by subtracting pretask distance refraction from posttask refraction, and regression was determined as the time for the posttask refraction to return to pretask levels. There were significant, but small, effects of text type (Chinese, 0.97 ± 0.32 diopters [D] vs. English, 1.00 ± 0.37 D; F1,1230 = 7.24, p = 0.007) and reading distance (33 cm, 1.01 ± 0.30 D vs. 25 cm, 0.97 ± 0.39 D; F1,1230 = 7.74, p = 0.005) on accommodation accuracy across all participants. Accuracy was similar for emmetropic and myopic children across all reading tasks. Neither text type nor reading distance had significant effects on NITM or its regression. Myopes had greater NITM (by 0.07 D) (F1,81 = 5.05, p = 0.03) that took longer (by 50s) (F1,81 = 31.08, p < 0.01) to dissipate. Reading Chinese text caused smaller accommodative lags than reading English text, but the small differences were not clinically significant. Myopic children had significantly greater NITM and longer regression than emmetropic children for both texts. Whether differences in NITM are a cause or consequence of myopia cannot be answered from this study.

Accommodative response and nearwork-induced transient myopia induced by simplified and traditional Chinese characters

Background Epidemiologic studies found that the incidence of myopia is higher in Hong Kong and Taiwan regions of China than that of the mainland.So whether the general reading words with traditional Chinese characters and simplified characters is associated with myopia deserves attention.Objective This study was to test the accommodative responses and the regression levels of nearwork-induced transient myopia (NITM) induced by traditional complex Chinese characters and modern simplified ones in the same size,and to explore the differences and inherent relationship of the accommodative regulations based on the structures of the two types of Chinese character in causing reading triggered myopia.Methods Twenty two volunteers aged 24-29 years were included in this study with informed consent.The corrected vision of both eyes from each subject was ≥ 1.0 with a mean spherical equivalence of (-1.86±2.34)D.Accommodative response was tested with 4 different reading texts using the rapid sequence visual presenting model with the GRAND SEIKO-WV5500 infrared autorefractor,and this procedure was performed after full correction of refractive error.An initial test of looking at a certain distance was performed (as baseline),and then the subjects read intensively at the targets for 10 minutes at 33 cm to calculate the accommodative responses.After a 10 second pause,the ocular refractive status was obtained exactly at 15 seconds,20 seconds.The one-way ANOVA method was used to determine the effects of the different font types and sizes on the adjustive responses and the causation of NITM.Results Accommodative response induced by simplified and traditional Chinese characters showed an accommodative lag of (1.11 ±0.38),(0.95 ±0.43),(1.18 ±0.33) and (1.06±0.28) D,showing a significant difference among the 9 pt and 12 pt simplified and traditional Chinese characters (F =1.62,P =0.19),and significantly different accommodative lag values between 12 pt simplified characters and 9 pt traditional characters was found (t =5.56,P =0.02).NITM induced by the four different targets were (-0.45 ±0.45),(-0.47 ±0.46),(0.45 ±0.82) and (-0.46±0.78) D in the 4 types of characters,without a significant difference among them (F=0.01,P =0.99).Conclusions Near-distance reading causes accommodative lag regardless of the type of reading texts.The target demonstrated stimuli spatial frequency and font size play an impact on accommodative responses.NITM appears when one reads simplified or traditional Chinese for 10 minutes.The accommodative lag and NITM trend might be responsible for the onset or regression of myopia,yet it is not supportive for the hypothesis that reading traditional Chinese causes more strain since there is no difference between the two. Key words: Myopia; Accommodative response; Nearwork-induced transient myopia; Chinese character/simplified, traditional

Baseline Characteristics of Nearwork-Induced Transient Myopia

The purpose of the present study was to describe the baseline refractive and nearwork-induced transient myopia (NITM) characteristics of the Beijing Myopia Progression Study, a 3-year cohort study, that has three overall specific aims: to investigate the natural history of NITM in schoolchildren living in the inner city of Beijing aged between 7 and 17 years; to investigate the possible relation between NITM and permanent myopia; and to determine the possible associations with NITM (eg, parental history). Three hundred eighty-six students (187 males and 199 females) were enrolled. The mean ages were 8.4 ± 1.1 years and 14.2 ± 1.6 years for the primary school and secondary school students, respectively. Baseline refractive aspects were determined clinically. Initial NITM and its decay were assessed objectively immediately after binocularly viewing and performing a sustained near task (5 minutes; 5 diopters [D]), incorporating a cognitive demand with full distance refractive correction in place. Initial NITM (mean ± SD) / decay time (median, first quartile, and third quartile) was 0.18 ± 0.16 D / 50 (20, 90) seconds, 0.09 ± 0.13 D / 30 (10, 40) seconds, and 0.10 ± 0.19 D / 20 (10, 40) seconds among the myopic, emmetropic, and hyperopic students, respectively, for the combined school levels. Initial NITM and decay time were significantly larger/longer in the myopic versus the other two refractive groups. The present findings demonstrate that in a large sample of school-aged children with myopia, the initial NITM magnitude was significantly larger and the decay duration was significantly longer than that observed in age-matched children with either emmetropia or hyperopia. Follow-up for the next 3 years will provide insight into the possible role of NITM in the development of permanent myopia.

The effect of simplified and traditional chinese character on accommodative reponses in myopes and emmtropes

AbstractPurpose This study investigated the effect of simplified and traditional chinese character on accommodative lag, accommodation microfluctuation, near work‐induced transient myopia (NITM) during the near task as well as the subsequent decay time. We aimed to analyze if the traditional Chinese character had the trend of inducing the myopia progress.Methods Young adults were classified into emmetropes and myopes . Two size (12pt,8pt) and two type (simplified and traditional chinese character) were used to give four different reading targets on computer screen. It was presented in random order at 25 cm and was read for 5min. For each target, accommodation response , accommodation microfluctuation NITM and its decay were measured using the free space Grand‐Seiko auto‐refractor.Results For myopic subjects, accommodation microfluctuation was greater for traditional chinese character 0.35±0.17 D than for simplified chinese character: 0.29 ±0.11 D, (p=0.017) ,NITM was larger for traditional chinese traditional character 0.61±0.34 D than for simplified chinese character 0.53±0.33 D,p=0.028, however there was no difference in emmetropic subjects. Myopes had larger accommodation microfluctuation 0.35±0.17 D than emmetrope 0.24±0.11 D p=0.02,myopes had greater NITM0.61±0.34 D than emmetropes 0.42±0.25 D P=0.013. For all targets, The accommodative lag of myopes is 0.74±0.32 D while the emmetropes 0.53±0.35 D P=0.000 ;The decay time for myopes was15.88±19.53 seconds while the emmetropes 9.04±12.62 seconds P=0.012.Conclusion The study showed that compare to the simplified Chinese character, the traditional chinese character had significant effect on myopic subjects, it may be more susceptible of inducing the myopia progress.

Three-Dimensional Display-Induced Transient Myopia and the Difference in Myopic Shift between Crossed and Uncrossed Disparities

To investigate whether three-dimensional (3D) images cause nearwork-induced transient myopia (NITM) more than 2D images and whether there is any difference between 3D images with crossed and uncrossed disparities in the development of NITM. Twenty-five volunteers, enrolled in this study, watched 2D and 3D movies and read 3D texts with crossed and uncrossed disparities for 2 to 3 hours with spectacle correction. The viewing distance was 50 to 70 cm. The refractive error was measured before and after each visual task. If there was a myopic shift after a task, the refractive error was measured at 3-minute intervals until it was resolved. The changes in the refractive error and the amount of NITM were evaluated and compared. The mean age of volunteers was 27.8 ± 2.87 years, and the mean refractive error before the visual tasks was -4.19 ± 2.87 diopters (D). Thirteen subjects (52%) showed NITM after watching a 2D movie, whereas 20 subjects (80%) had NITM after a 3D movie (P = 0.037). The mean extent of NITM was 0.36 ± 0.27 D after watching a 3D movie and 0.10 ± 0.28 D after a 2D movie (P = 0.002). The 3D text with crossed disparity significantly induced NITM (P < 0.001), but that with uncrossed disparity did not. There was a tendency for the NITM to persist longer after subjects watched a 3D movie than after a 2D movie. Viewing 3D images with crossed disparity induced a greater degree of NITM than 2D images. These results suggest that the greater NITM induced by 3D images may have a greater effect on the development and progression of permanent myopia.

Advances in near work-induced transient myopia

The possible mechanism of myopia remains controversial while gene and environment are two generally acknowledged factors underlie the development of human myopia. Near work which is a primary, environmentally based factor in the development and progression of permanent myopia (PM) may take effect via near work-induced transient myopia (NITM). In this review, the definition, measuring procedure and relative evaluation parameters of NITM as well as its characteristics, methods for reducing NITM and its possible mechanisms reported in the literature will be summarized.

A Method for Profiling Biometric Changes During Disaccommodation

To demonstrate the application of low-coherence reflectometry to the study of biometric changes during disaccommodation responses in human eyes after cessation of a near task and to evaluate the effect of contact lenses on low-coherence reflectometry biometric measurements. Ocular biometric parameters of crystalline lens thickness (LT) and anterior chamber depth (ACD) were measured with the LenStar device during and immediately after a 5 D accommodative task in 10 participants. In a separate trial, accommodation responses were recorded with a Shin-Nippon WAM-5500 optometer in a subset of two participants. Biometric data were interleaved to form a profile of post-task anterior segment changes. In a further experiment, the effect of soft contact lenses on LenStar measurements was evaluated in 15 participants. In 10 adult participants, increased LT and reduced ACD was seen during the 5 D task. Post-task, during fixation of a 0 D target, a profile of the change in LT and ACD against time was observed. In the two participants with accommodation data (one a sufferer of nearwork-induced transient myopia and other a non-sufferer), the post-task changes in refraction compared favorably with the interleaved LenStar biometry data. The insertion of soft contact lenses did not have a significant effect on LenStar measures of ACD or LT (mean change: -0.007 mm, p = 0.265 and + 0.001 mm, p = 0.875, respectively). With the addition of a relatively simple stimulus modification, the LenStar instrument can be used to produce a profile of post-task changes in LT and ACD. The spatial and temporal resolution of the system is sufficient for the investigation of nearwork-induced transient myopia from a biometric viewpoint. LenStar measurements of ACD and LT remain valid after the fitting of soft contact lenses.