The impact of different postures on acute intraocular pressure and accommodation responses during reading.

INTRODUCTION: To investigate the effects of different reading postures on intraocular pressure (IOP) and near-work-induced transient myopia (NITM) in children with myopia. METHODS: Sixty myopic children were instructed to read a book text placed at 33 cm for 30 min with two different reading postures: head bowed and head upright postures. The participants' IOP and NITM were assessed using a rebound tonometer and an open-field autorefractor. The measurement of IOP was conducted prior to reading, during reading sessions (at 5, 10, 20, and 30-min intervals), and after a 5-min recovery period. RESULTS: For the head bowed posture, the mean baseline IOP was 16.13 ± 2.47 mmHg. A significant rise in IOP was observed after 5 min of reading (17.17 ± 2.97 mmHg; +1.03 ± 2.29 mmHg; p = 0.014). Subsequent measurements revealed a further increase after 20 min (17.87 ± 2.90 mmHg; +1.73 ± 2.58 mmHg; p < 0.001), which continued to persist even after 30 min of reading (17.57 ± 3.46 mmHg; +1.43 ± 2.66 mmHg; p = 0.002). The IOP at different time points measured in the head upright posture did not show any significant difference in comparison to the baseline measurement (all p = 1.000). Compared to reading with the head upright, reading with the head bowed resulted in a greater increase in IOP at each time point (p < 0.05). Furthermore, the NITM was higher for reading with the head bowed than for reading with head upright at 30 min (-0.24 ± 0.53 D vs. -0.12 ± 0.47 D, p = 0.038). CONCLUSION: Reading in a head bowed position resulted in greater increases in IOP and NITM compared to reading in a head upright posture.

Association between whole-grain intake and myopia in chinese children: a cross-sectional epidemiological study.

BACKGROUND: Nutritional status influences the growth and development of the eyes. However, there are few studies on the association between diet, especially whole grains (WG) consumption, and myopia. The study aimed to evaluate the association between WG intake and myopia prevalence among primary school-age children in China. METHODS: This cross-sectional epidemiological study conducted between November 2019 and December 2019 included 586 children, aged 6-12 years, attending primary school in Binhai district, Tianjin, China. Ophthalmologic examinations and optometric cycloplegic refraction measurements were conducted. Information was collected on known risks and protective factors for myopia and the consumption of WGs, vegetables, and fruits. This association between the probability of myopia and the proportion of WG consumption (WG proportion was calculated as the mean intake from WG sources divided by total grain intake), adjusted for protective and risk factors, was analysed using crude and multivariable logistic regression. RESULTS: Among the study participants, 226/586 (38.57%) children had myopia in at least one eye. WG intake was inversely correlated with the prevalence of myopia. Furthermore, in the multivariate analysis, WG intake of > 50% was identified as a protective factor against myopia after subsequent adjustment for children's age, sex, parental myopia, near-work activity, screen time, reading and writing habits, visual fatigue, outdoor time, and classroom light environment (all P < 0.05). CONCLUSION: WG intake (> 50%) was an independent protective factor against myopia. Modifying the form of grains consumed (whole versus refined) could be one of the targets of future public health measures.

Risk factors for anisometropia in schoolchildren: A population-based, longitudinal cohort study.

PURPOSE: To investigate the incidence rate and risk factors for anisometropia among young schoolchildren. METHODS: A population-based cohort study, the Myopia Investigation Study in Taipei, was conducted in primary schools in Taipei City. Children were recruited for biannual comprehensive eye examinations over 2 years. Cycloplegic autorefraction and slit lamp examinations were performed biannually. Data on demographic information, parental history, lifestyle and near-work activities were collected using parent-administered questionnaires at the first and final visits. Anisometropia was defined as ≥1 D difference in the spherical equivalent (SE) refractive error. RESULTS: A total of 7035 8-year-old children completed the 2-year follow-up evaluations. The average annual incidence of anisometropia was 3.8%. Multivariable logistic regression analysis revealed that baseline SE (odds ratio [OR]: 0.87 95% CI: 0.80-0.95) and female sex (OR: 1.24, 95% confidence interval [CI]: 1.02-1.50) were significantly associated with incident anisometropia. Among lifestyle risk factors, spending <1 h per day in after-school outdoor activities on weekdays (OR: 1.38, 95% CI: 1.08-1.76) and performing near work at a distance <30 cm (OR: 1.33, 95% CI: 1.08-1.64) were significantly associated with an increased risk of incident anisometropia. In the multiple linear regression analysis, the inter-eye difference in SE increased significantly in children performing near work at distances <30 cm (adjusted ß = 0.03; p = 0.02). CONCLUSIONS: This study indicated the annual incidence of anisometropia in Taiwanese schoolchildren. Less time spent outdoors and shorter eye-to-object distances during near work increased the risk of incident anisometropia.

Higher order aberrations and retinal image quality during short-term accommodation in myopic and non-myopic children.

INTRODUCTION: Despite the known associations between near work and myopia, and retinal image quality and eye growth, accommodation-induced changes in higher order aberrations (HOA's) and retinal image quality in children with different refractive errors are poorly understood. METHODS: Ocular HOA's were measured using a Hartmann-Shack wavefront sensor (COAS-HD, Wavefront Sciences) in 18 myopic and 18 age- and sex-matched non-myopic children during short-term accommodation tasks (four demands of 0, 3, 6 and 9 D) presented using a Badal optometer. Eighth order Zernike polynomials were fitted across a 2.3 mm pupil diameter to determine refractive power vectors (M, J180 and J45 ) and the accommodation error, and a 4 mm pupil was used for HOA analyses. Retinal image quality was examined using the visual Strehl ratio based on the optical transfer function (VSOTF) for third to eighth radial orders only. RESULTS: Most refractive error group differences were observed for the 6 and 9 D demands. Myopic children underwent greater changes in with-the-rule astigmatism (J180 ), higher order and third order RMS values, primary vertical ( C 3 - 1 ) and horizontal coma ( C 3 1 ), and several other individual Zernike coefficients compared with non-myopic children (all refractive error group by demand interaction p-values of ≤0.02). Non-myopic children exhibited a greater negative shift in primary ( C 4 0 ) and positive shift in secondary spherical aberration ( C 6 0 ) (both refractive error group by demand interaction p-values of ≤0.002). The VSOTF degraded for the 6 and 9 D demands in both groups, but the myopic children underwent a greater mean (SE) reduction from 0 D of -0.274 (0.048) for the 9 D demand, compared with -0.131 (0.052) for the non-myopic children (p = 0.001). CONCLUSION: These results may have implications for the association between near work, accommodation and myopia development, particularly related to the use of short working distances during near tasks.

Near work induces myopia in Guinea pigs.

The association between near work activities and myopia has not been clearly established. This study establishes a model for near work myopia (NWM) induced by short viewing distance in guinea pigs with a carefully controlled visual environment, and evaluates the effect of viewing distance in myopia development. Pigmented guinea pigs (3 weeks old) were randomly assigned to 3 groups: near work (NW)-, form-deprivation (FD)-, and -4D hyperopic-defocus (HD)-induced myopia. Animals in NW groups were kept in cylindrical cages with vertical square-wave gratings, providing short- (S, d = 18 cm), middle- (M, d = 44 cm), and long- (L, d = 88 cm) mean viewing distances, all at the same illuminance, during daily treatment for 14 days. Biometric parameters, including refraction, anterior chamber depth (ACD), lens thickness (LT), vitreous chamber depth (VCD), and axial length (AL), were measured at the beginning and end of 14 days' treatment. Choroidal thickness (ChT) and choroidal blood perfusion (ChBP) were measured by optical coherence tomography (OCT) and OCT-angiography (OCTA), respectively, at the end of treatment. Refraction was shifted towards myopia in the S-cage group, compared with the M- and L-cage groups; refractions in the L-, M- and S-cage groups were 5.19 ± 0.65 D, 4.30 ± 0.64 D, and 0.53 ± 0.61 D, respectively (p < 0.001). VCD and AL in the S-cage group increased in parallel with the myopic shift (L vs M vs S: VCD: 3.15 ± 0.02 mm vs 3.17 ± 0.02 mm vs 3.26 ± 0.02 mm, p < 0.001; AL: 7.99 ± 0.03 mm vs 8.03 ± 0.03 mm vs 8.15 ± 0.02 mm, p = 0.001). In FD and HD eyes, changes similar to those in the S-cage group (near-work group, NW) were seen in refraction (NW vs FD vs HD: 5.36 ± 0.82 D vs -5.78 ± 0.44 D vs -4.96 ± 0.54 D, p = 0.734), ACD, LT, VCD and AL. Also, ChT and ChBP were significantly less in the S-cage group than in the M- and L-cage groups after 14 days' treatment (L vs M vs S: ChT: 74.84 ± 3.27 vs 76.07 ± 3.49 vs 61.95 ± 3.31, P = 0.002; ChBP: 48.32 ± 2.23 vs 48.66 ± 2.30 vs 38.14 ± 2.06, p = 0.002). Rearing in S-cages induced myopia in guinea pigs and correspondingly decreased ChBP and ChT. The present study provides objective evidence that short viewing distance could be a risk factor for myopia, and describes a useful model for studying the underlying mechanisms.

The relationship between myopia and near work, time outdoors and socioeconomic status in children and adolescents.

BACKGROUND: To investigate environmental and social risk factors for myopia in children and adolescents in Germany. METHODS: 1437 children aged between 3 and 18 inclusive were examined as part of the LIFE Child study based in Leipzig, Germany. Information about leisure time activities and social status was ascertained by parents and children in a questionnaire. Refractive status was attained by measuring noncycloplegic autorefraction. Myopia was defined as spherical equivalent (SE) ≤ - 0.75 D. Risk factors were identified using multiple logistic regression analysis. RESULTS: In multiple logistic regression analysis, myopia was significantly associated with less frequent outdoor activity ("once a week" vs. "twice a week or more": odds ratio (OR) 4.35, 95% confidence interval (CI) 1.89-9.98, p<0.01) and longer near work sessions (1-2 h vs. < 1 h: OR 1.83, CI 1.10-3.04, p=0.02; > 3 h vs. < 1 h: OR 3.71, CI 1.43-9.61, p<0.01) after adjustment for age, sex and socioeconomic status (SES). Duration of outdoor activity, near work frequency and SES showed no significant association with myopia (p > 0.05). Children with a lower SES were involved in longer periods of outdoor and near work activities but on fewer occasions over the course of the week, although this connection was not significant. CONCLUSION: Myopia is associated with environmental factors. The present findings suggest that daily exposure to sunlight and a restriction of long-duration near work activities might protect against pathological eye growth. Prevention strategies should be implemented for children at all ages.

Influence of parental behavior on myopigenic behaviors and risk of myopia: analysis of nationwide survey data in children aged 3 to 18 years.

BACKGROUND: Preventive parental behavior may play an important role in the outcomes of children's myopia. We investigated associations between parental behavior and children's myopia status and daily activities using data from the most recent myopia survey in Taiwan. METHODS: In total, 3845 children aged 3 to 18 years who completely responded to the questionnaire were included (total score ranging from 0 to 75). A score of ≥ 50 was considered to indicate beneficial parental behavior. Time allocation data for near-work activities, using electronic devices, and outdoor activities were collected using a separate self-reported questionnaire. Associations between beneficial parental behavior and children's myopia status and activity patterns were analyzed and stratified by school level. RESULTS: Beneficial parental behavior was positively associated with children's myopia in the overall samples [adj. odds ratio (OR): 1.31, 95% confidence interval (CI): 1.08-1.59, p = 0.006)] and at the elementary school level (adj. OR: 1.43, 95% CI: 1.11-1.83, p = 0.005). However, a negative association with high myopia was observed in the overall samples (adj. OR: 0.71, 95% CI: 0.50-0.99, p = 0.049) and high school level (adj. OR: 0.62, 95% CI: 0.41-0.92, p = 0.02). Beneficial parental behavior was associated with less time spent on near work (≥ 180 min/day) and electronic device use (≥ 60 min/day), but not with outdoor activities. CONCLUSION: In Taiwan, children's myopia is associated with higher rate of parents' beneficial behaviors, which suggests that regular vision surveillance is necessary to promote better parental behavior toward children's eye care. Certain parental practices may influence children's behavior pattern and reduce the risk of children's high myopia development in the long run.

Anterior scleral thickness and shape changes with different levels of simulated convergence.

PURPOSE: Convergence plays a fundamental role in the performance of near visual tasks. We measured the effect of two levels of convergence on anterior scleral thickness and shape in emmetropes, low to moderate myopes and high myopes. METHODS: Forty-five healthy young adults aged between 18 and 35 years including 15 emmetropes, 15 low/moderate myopes, and 15 high myopes were recruited. Anterior segment optical coherence tomography and eye surface profilometry were used to evaluate the anterior scleral thickness (nasal only, n = 42) and shape (n = 40), before and during two visual tasks involving 9° and 18° convergence, in those participants with complete and reliable data. RESULTS: Convergence led to a thickening of the total anterior eye wall (5.9 ± 1.4 µm) and forward movement (10 ± 2 µm) of the nasal anterior scleral surface (both p < 0.001). Larger changes were found at 18° than at 9° convergence and in more peripheral nasal scleral regions. There was a significant association between total wall thickening and forward movement of the scleral surface. Refractive group was not a significant main effect, but there were significant interactions between refractive group and the thickness changes with convergence in different scleral regions. CONCLUSION: During convergence, the biomechanical forces acting on the eye lead to nasal anterior scleral thickening and forward movement of the nasal scleral surface.

The relationship between education levels, lifestyle, and religion regarding the prevalence of myopia in Israel.

BACKGROUND: The ultra-Orthodox Jewish community has a unique lifestyle including minimal outdoor activity and intense, prolonged nearby work, beginning at a very young age. Their prevalence of myopia is extremely high. This paper provides a unique insight into the attitudes of this community towards myopia. METHODS: Ultra-Orthodox Jewish parents of children who came to the pediatric ophthalmology clinic in one tertiary care and two community centers in ultra-Orthodox-oriented cities were given a questionnaire. Demographic information, along with myopia prevalence in the family, was gathered. In addition, their attitudes and common knowledge regarding myopia were investigated. RESULTS: 161 questioners were collected, mostly completed by mothers (n = 110, 68%). The average number of children per family was 6 (range 1-16). In 148 families (92%) at least one of the parents has myopia. The average parent refraction was - 4.5 diopters (range - 0.5 to 15 diopters). Out of 935 children, 410 (44%) wore glasses. Twelve parents (7%) believe that myopia is a disease and 94 (58%) reported that they are concerned because their child wears glasses. Twenty-four (15%) believe that glasses are a sign of a high education level. Regarding treating myopia progression, 144 (89%) think that myopia progression should be treated, but only 36 (22%) are aware of the available treatments for it. CONCLUSION: This study examines an insular community with a very high incidence of myopia. In this community most parents think that myopia progression should be treated but most of them are unaware of the currently available treatments.

Reliability and validity of the Actiwatch and Clouclip for measuring illumination in real-world conditions.

PURPOSE: To compare real-world measures of illumination obtained with the Actiwatch-2 and Clouclip-M2 with 'gold standard' photometry measures and to evaluate the ability of Actiwatch-2 to correctly identify photometer-defined conditions: scotopic (≤0.01 lux), mesopic (0.02-3 lux), indoor photopic (>3-1,000 lux) and outdoor photopic (>1,000 lux); and Clouclip to correctly identify photometer-defined conditions within its operating range (>1 lux). Inter-device reliability of Clouclip for illumination and viewing distance measures was also investigated. METHODS: A Hagner-S2 photometer was used as reference. Measures of illumination were obtained from a range of real-world conditions. To investigate inter-device reliability, five Clouclips were simultaneously exposed to varied light conditions and object distances. RESULTS: Strong correlations existed between illumination measured with the photometer and both Actiwatch-2 (ρ = 0.99, p < 0.0001) and Clouclip (ρ = 0.99, p < 0.0001). However, both devices underestimated illumination compared to the photometer; disparity increased with increasing illumination and was greater for Actiwatch-2 than Clouclip measures. Actiwatch-2 successfully categorised illumination level (scotopic, mesopic, indoor and outdoor photopic) in 71.2% of cases. Clouclip successfully categorised illumination levels as scotopic/mesopic (≤3 lux) and indoor and outdoor photopic in 100% of cases. Mean differences and limits of agreement (LOA) were 430.92 ± 1,828.74 and 79.35 ± 407.33 lux, between the photometer and Actiwatch-2 and photometer and Clouclip, respectively. The Intra-class Correlation Coefficients for illumination and viewing distance measured with five Clouclips were 0.85 and 0.96, respectively. CONCLUSION: These data illustrate that different Clouclip devices produce comparable measures of viewing distance and illumination in real-world settings. Both Actiwatch-2 and Clouclip underestimate illumination in the field compared to gold standard photometer measures. The disparity increases at higher levels of illumination and the discrepancy was greater for Actiwatch-2 measures. For researchers interested in categorising light exposure, Clouclip classifies illumination levels >2 lux more accurately than Actiwatch-2 but cannot discriminate between scotopic and low mesopic light.

Wearable Sensors for Measurement of Viewing Behavior, Light Exposure, and Sleep.

The purpose of this study was to compare two wearable sensors to each other and to a questionnaire in an adult population. For one week, participants aged 29.2 ± 5.5 years (n = 25) simultaneously wore a Clouclip, a spectacle-mounted device that records viewing distance and illuminance, and an Actiwatch, a wrist-worn device that measures illuminance and activity. Participants maintained a daily log of activities and completed an activity questionnaire. Objective measures of time outdoors, near (10-< 60 cm) and intermediate (60-100 cm) viewing, and sleep duration were assessed with respect to the daily log and questionnaire. Findings showed that time outdoors per day from the questionnaire (3.2 ± 0.3 h) was significantly greater than the Clouclip (0.9 ± 0.8 h) and Actiwatch (0.7 ± 0.1 h, p < 0.001 for both). Illuminance from the Actiwatch was systematically lower than the Clouclip. Daily near viewing duration was similar between the questionnaire (5.7 ± 0.6 h) and Clouclip (6.1 ± 0.4 h, p = 0.76), while duration of intermediate viewing was significantly different between methods (p < 0.001). In conclusion, self-reported time outdoors and viewing behaviors were different than objective measures. The Actiwatch and Clouclip are valuable tools for studying temporal patterns of behavioral factors such as near work, light exposure, and sleep.

Stopping the rise of myopia in Asia.

This review discusses the rapid rise of myopia among school-age children in East and Southeast Asia during the last 60 years. It describes the history, epidemiology, and presumed causes of myopia in Asia, but also in Europe and the United States. The recent myopia boom is attributed primarily to the educational pressure in Asian countries, which prompts children to read for long hours, often under poor lighting and on computer screens. This practice severely limits the time spent outdoors and reduces exposure to sunlight and far vision. As a consequence, the eyes grow longer and become myopic. In a breakthrough study in Taiwan, it has been found that by increasing the time spent outdoors, the incidence of new myopia cases was reduced to half when children were sent onto the schoolyard for at least 2 h daily. This protection is attributed to the light-induced retinal dopamine, which blocks the abnormal growth of the eyeball. Once myopia has set in, low-dose atropine and orthokeratology have shown positive results in slowing myopia progression. Also, prismatic bifocal lenses and specially designed multifocal soft contact lenses have recently been tested with promising results. Treatment, however, must be initiated early as the disease progresses once it has started, thereby enhancing the risk for severe visual impairment and ultimately blindness.

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.

Changes in ocular biometry during short-term accommodation in children.

PURPOSE: Near work has been linked with myopia development; however, the underlying mechanism remains unclear. Small increases in axial length during accommodation have previously been reported in adults, and therefore, this study aimed to examine if accommodation-induced changes in ocular biometry also occur in school-aged children. METHODS: A range of ocular biometric measurements were captured during brief accommodation tasks at four demands (0, 3, 6, and 9 D), in a group of 87 non-myopic, school-aged children using a Badal optometer mounted to a non-contact optical biometer (Zeiss IOLMaster 700, https://www.zeiss.com/meditec/int/product-portfolio/optical-biometers/iolmaster-700.html). Reliable biometry measurements and active accommodation were observed for 76 participants who were included in the analysis. The average central corneal thickness (CCT), anterior chamber depth (ACD), crystalline lens thickness (LT), anterior segment length (ASL), vitreous chamber depth (VCD), and axial length (AL) were determined for each accommodation demand. Raw measurements of AL and VCD were corrected to account for the effect of LT changes during accommodation. RESULTS: On average, AL increased with increasing levels of accommodation (p = 0.005). The mean (SEM, standard error of the mean) AL increase from 0 D to the 3, 6, and 9 D demands was 4 (1), 8 (1), and 15 (2) µm, respectively. All other biometric parameters, except CCT, changed significantly during accommodation. LT and ASL increased, and ACD and VCD decreased significantly with increasing accommodation (all p ≤ 0.02). A longer baseline AL was associated with greater levels of accommodation-induced axial elongation at the 9 D demand (p < 0.0001). CONCLUSIONS: AL increased significantly during accommodation in children, consistent with previous findings in adults up to a 6 D demand. AL continued to increase for higher levels of accommodation (9 D demand), which children may experience during near tasks. These findings provide further insights into potential mechanisms linking near work, axial elongation, and myopia development. However, no myopic children participated in this experiment; therefore, further research is required.

The diversified defocus profile of the near-work environment and myopia development.

PURPOSE: To quantify the defocus characteristics in the near-work environment at home and investigate the relationship with subsequent myopia progression. METHODS: Fifty subjects (aged 7-12 years) were recruited and followed for 1 year. The home near-work environment (writing desk) was measured at a baseline home-visit using the Kinect-for-Windows to capture a 3-dimensional image. The depth values of the image were then converted into scene defocus with respect to the subject's viewpoint. The defocus characteristics were quantified as the dioptric volume (the total amount of net defocus, or DV) and standard deviation of the defocus values (SDD ). Information on home size, time spent outdoors, and in front of a desk were also obtained. Univariate correlation, and multivariate regression were used to assess the association between myopia progression, defocus characteristics, and other co-variates. RESULTS: The baseline spherical equivalent refraction (M) and refraction change over 1 year (∆M) were - 1.51 ± 2.02 D and - 0.56 ± 0.45 D respectively. DV was not significantly correlated with ∆M (Spearman's ρ = -0.25, p = 0.08), while SDD was negatively correlated to ∆M (Spearman's ρ = -0.42, p = 0.003). Although SDD was not a significant predictor in multivariate analysis, the regional DV at 15°-20° eccentricity was significant (p = 0.001). Home size (F2,50  = 7.01, p = 0.002) and time spent outdoors (Independent t = -2.13, p = 0.04) were also associated with ∆M, but not time spent in front of desk (Independent t = 0.78, p = 0.44). CONCLUSION: The defocus profile in the home environment within the para-central field of view is associated with childhood refractive error development.

Validation of the Clouclip and utility in measuring viewing distance in adults.

PURPOSE: To validate the Clouclip, a continuously measuring objective rangefinder, and examine viewing behaviours during various near tasks in non-myopic and myopic adults. METHODS: In experiment 1, five Clouclip devices were utilised. An infrared camera was used to visualise and measure infrared beam size and angle. Repeatability for distance tracking was assessed from 5 to 120 cm in 5 cm increments. Accuracy of distance tracking was investigated for paper and iPad targets, spatial integration was calculated, effects of target tilt were determined and light measurements were compared to a lux meter. In experiment 2, viewing behaviour was assessed in 41 subjects (21 non-myopic, 20 myopic) during four 15-min near tasks; (1) passive reading of printed material, (2) active writing on printed material, (3) passive viewing on an electronic device and (4) active engagement on an electronic device. Working distance was compared between tasks and refractive error groups. RESULTS: Clouclip distance tracking showed good repeatability, with a mean difference of 0.34 cm and limits of agreement of ±2.0 cm. Clouclip-measured and actual distances were highly correlated for paper and electronic targets from 5 to 120 cm, with mean differences and limits of agreement of 3.96 ± 13.78 cm and 4.48 ± 8.92 cm, respectively; variability increased for distances >100 cm. Tracking ability increased with larger target sizes; tracking was accurate when the target occupied 1.5%-20.3% of tracking beam area, depending on distance and with target tilt up to ±60 degrees. Clouclip- and lux meter-measured ambient illumination were highly correlated for a wide range of intensities (r = 0.96, p < 0.001), but with greater variability for intensities >20 000 lux. The Clouclip infrared beam was measured to have a diameter of 25.6 ± 2.2° and a downward angle of 10.3 ± 0.5°. For subject testing, viewing distance was significantly closer for active and passive printed tasks (29.5 ± 6.7 cm and 33.2 ± 8.8 cm, respectively) than for active and passive electronic tasks (35.4 ± 8.0 cm and 40.8 ± 10.4 cm, respectively), with no differences between refractive error groups (p = 0.88). CONCLUSIONS: The Clouclip performed well in measuring near and intermediate distances and could distinguish between indoor (<1000 lux) and outdoor (>1000 lux) illumination. A closer working distance was observed for printed tasks compared to those on an iPad, with no difference in viewing distance between non-myopic and myopic adults.

Status of visual impairment among indigenous (Orang Asli) school children in Malaysia.

BACKGROUND: School children are considered a high-risk group for visual impairment because uncorrected refractive errors and problems such as amblyopia can seriously affect their learning abilities and their physical and mental development. There are many studies reporting the prevalence of refractive errors among school children of different ethnic groups in Malaysia, however, studies concerning the prevalence of refractive errors among indigenous or Orang Asli children are very limited. Therefore, the objective of this study was to determine the prevalence and causes of visual impairment among Orang Asli children. METHODS: One hundred ten Orang Asli children aged 7 to 12 years old in Negeri Sembilan, Malaysia were selected. 51% of these children were boys while the remainders were girls. They underwent visual acuity test, cover test, Hirschberg's test, ocular external assessment and ophthalmoscopy. Children who failed the vision screening were then referred for further eye examination. RESULTS: Of these 110 Orang Asli children, 46 failed the vision screening and subsequently 45 of them were confirmed to have visual problems (40.9% of the total subjects). The main cause of visual impairment in this study was refractive error (34.5% of the total subjects) where the main refractive error found was hyperopia (28.2%) followed by amblyopia (2.7%), strabismus (1.8%) and ocular abnormalities (1.8%). CONCLUSION: Hence, vision screening and a comprehensive eye examination is very important and needs to be done on all Orang Asli children so that any visual problems can be detect at an early stage to avoid the development of learning difficulties among these already disadvantaged children.

Near work, outdoor activity, and myopia in children in rural China: the Handan offspring myopia study.

BACKGROUND: The near work and outdoor activity are the most important environmental risk factors for myopia. However, data from Chinese rural children are relatively rare and remain controversial. Therefore, the purpose of this study was to evaluate the relationship of both near work and outdoor activities with refractive error in rural children in China. METHODS: In this cross-sectional study, 572 (65.1%) of 878 children (6-18 years of age) were included from the Handan Offspring Myopia Study (HOMS). Information from the parents on these children, as well as the parent's non-cycloplegic refraction, were obtained from the database of the Handan Eye Study conducted in the years 2006-2007. A comprehensive vision examination, including cycloplegic refraction, and a related questionnaire, were assessed on all children. RESULTS: The overall time spent on near work and outdoor activity in the children was 4.8 ± 1.6 and 2.9 ± 1.4 h per day, respectively. Myopic children spent more time on near work (5.0 ± 1.7 h vs.4.7 ± 1.6 h, p = 0.049), while no significant difference was found in outdoor activity hours (2.8 ± 1.3 h vs. 3.0 ± 1.4 h, p = 0.38), as compared to non-myopic children. In the multiple logistic analysis, in general, no association between near work and myopia was found after adjusting for the children's age, gender, parental refractive error, parental educational level, and daily outdoor activity hours [odds ratio (OR), 95% confidence interval (CI): 1.10, 0.94-1.27]. However, a weak protective effect of the outdoor activity on myopia was found (OR, 95% CI: 0.82, 0.70-0.96), after adjusting for similar confounders. CONCLUSIONS: In general, no association between near work and myopia was found, except for the high near work subgroup with moderate outdoor activity levels. A weak protective effect of outdoor activity on myopia in Chinese rural children was observed.

The influence of near work on myopic refractive change in urban students in Beijing: a three-year follow-up report.

PURPOSE: To investigate the influence of daily activities on myopic refractive change and myopic onset in Chinese urban students. METHODS: The Beijing Myopia Progression Study was a 3-year cohort study. Cycloplegic refraction and a daily activity questionnaire were assessed at baseline and at follow-up examinations. Refractive change was defined as the difference in cycloplegic spherical equivalent (SE) between the final follow-up and baseline. 386 students were initially enrolled in the baseline study. RESULTS: At the final follow-up, 222 students (57.5 %) with completed refractive error and daily activity data were analyzed. These students spent 0.32 ± 2.33 h/day more on near work (p = 0.04), and 0.21 ± 1.31 h/day less on outdoor leisure (p = 0.02), than they did at baseline. In the multivariate analysis, the younger among the secondary students (ß = 0.06, p < 0.001), and those with more near work hours at baseline (ß = -0.028, p = 0.033), exhibited more myopic refractive change. However, myopic refractive change was not found to be significantly associated with near work hours in the primary students, or with time spent outdoors, in either school level. After stratifying the activity hours into quartile groups, students with a greater near work load at baseline (trend P = 0.03) exhibited a greater myopic refractive change and had a higher risk to develop myopia (hazard ratio, 95 % confidence interval: 5.19, 1.49-18.13), after adjusting for the confounders. However, no significant association was found related to outdoor activity. CONCLUSIONS: In this cohort, children with a greater near work load at baseline exhibited more myopic refractive change and were also more likely to develop myopia. The protective effect of outdoor activity on myopic refractive change was not observed.

The effect of refractive error on the accommodative response gradient: a summary and update.

PURPOSE: To give a summary of the original paper 'The effect of refractive error on the accommodative response gradient' published in 1986 and to present a brief overview of the most salient, subsequent findings which have appeared since then. RECENT FINDINGS: Intensive and prolonged near work as a precursor to myopia has been substantiated since the original paper and is thought to contribute to the remarkable increase in the prevalence of myopia in the world which has occurred in the last 30 years, consistent with the emergence of compulsory education, computers and urbanisation. Increased accommodation has not been found to be essential in the development of myopia, but inaccurate accommodation during near work in the form of accommodative lag with its consequent hyperopic defocus has been confirmed as an association with myopia, although it is not clear whether that association is causal or merely a consequence of myopia. SUMMARY: The premise of the original paper that near work engenders lower accommodation in myopes compared to emmetropes and hyperopes has been corroborated over the years, particularly in progressing myopes as distinct from stable adult myopes. Inaccurate accommodation resulting in accommodative lag has been amply confirmed in subsequent studies.