Ocular Biometry Percentile Curves and Their Relation to Myopia Development in Indian Children.

Background: The aim of the present study was to provide ocular biometry percentile values for Indian children between the ages of 6 and 12 and to validate the usefulness of centiles in predicting myopia development. Methods: The study was part of a longitudinal study-the Sankara Nethralaya Tamil Nadu Essilor Myopia Study (STEM), where objective refraction and ocular biometry were measured for children studying in grades 1, 4, and 6 at baseline (2019-2020). These data were used to generate ocular biometry percentile curves (both for axial length (AL) and AL/corneal curvature (AL/CR) ratios). The usefulness of percentile values in predicting myopia development was estimated from follow-up data (2022). Results: The total number of children in the three grades at baseline was 4514 (age range 6 to 12). Boys represented 54% (n = 2442) of the overall sample. The prevalence of myopia at baseline was 11.7% (95% CI from 10.8 to 12.7%) in these three grades. Both the AL and AL/CR ratio centiles showed a linear trend with an increase in AL and AL/CR with increasing grades (p < 0.001) for all percentiles (2, 5, 10, 25, 50, 75, 90, 95, 98, and 99) when stratified by sex. In the follow-up data (n = 377), the 75th and 50th percentiles of the AL/CR ratio had an area under the curve (AUC) of 0.79 and 0.72 to predict myopia onset for grade 4 and 6 children at baseline. Combining baseline AL with the centile shift in follow-up as a predictor increased the AUC to 0.83. Conclusions: The present study has provided centile values specific for Indian children between the ages of 6 and 12 to monitor and intervene where children are at a higher risk of myopia development.

Myopia and Its Association with Near Work, Outdoor Time, and Housing Type among Schoolchildren in South India.

SIGNIFICANCE: In this comprehensive assessment of environmental associations with refractive status among schoolchildren in India, outdoor time was the key modifiable risk factor associated with myopia rather than time spent on near work. PURPOSE: This study aimed to investigate the environmental risk factors associated with myopia among adolescent schoolchildren in South India. METHODS: Children in grades 8 to 10 from 11 schools in Tamil Nadu, South India, underwent eye examination and risk factor assessments through a modified version of the Sydney myopia questionnaire. Time spent on near work and outdoors was analyzed after division into three groups based on tertiles. Mixed-effects logistic regression was performed to assess the factors associated with myopia. RESULTS: A total of 3429 children (response rate, 78.4%) provided both questionnaire and refraction data. The mean (standard deviation) age was 14 (0.93) years with an equal distribution of sexes. Myopia was present among 867 children (noncycloplegic spherical equivalent refraction, ≤-0.75 D). Refraction was not associated with near work tertiles ( P = .22), whereas less time outdoors was associated with higher myopic refractions ( P = .01). Refraction shifted toward increased myopia with an increase in the near-work/outdoor time ratio ( P = .005). Children living in apartment housing had a higher prevalence of myopia compared with other types of housing ( P < .001). In multivariate analysis, increased time outdoors was a protective factor against myopia (odds ratio, 0.79; 95% confidence interval, 0.63 to 0.99; P = .04), whereas living in apartment housing (odds ratio, 1.27; 95% confidence interval, 1.04 to 1.55; P = .02) was a significant risk factor. CONCLUSIONS: In this cohort of Indian children, outdoor time, increased near-work/outdoor time ratio, and type of housing were the factors associated with myopia. Policies should target implementing a balance between near-work and outdoor time among children.

A cohort study for the development and validation of a reflective inventory to quantify diagnostic reasoning skills in optometry practice.

BACKGROUND: Diagnostic reasoning is an essential skill for optometry practice and a vital part of the curriculum for optometry trainees but there is limited understanding of how diagnostic reasoning is performed in optometry or how this skill is best developed. A validated and reliable self-reflective inventory for diagnostic reasoning in optometry, would enable trainees and registered practitioners to benchmark their diagnostic reasoning skills, identify areas of strength and areas for improvement. METHODS: A 41 item self-reflective inventory, the Diagnostic Thinking Inventory, used extensively in the medical field was adapted for use in optometry and called the Diagnostic Thinking Inventory for Optometry (DTI-O). The inventory measures two subdomains of diagnostic reasoning, flexibility in thinking and structured memory. Context based changes were made to the original inventory and assessed for face and content validity by a panel of experts. The inventory was administered to two groups, experienced (qualified) optometrists and second-year optometry students to establish validity and reliability of the self-reflective tool in optometry. RESULTS: Exploratory Factor Analysis uncovered 13 domain specific items were measuring a single construct, diagnostic reasoning. One misfitting item was removed following Rasch analysis. Two unidimensional subdomains were confirmed in the remaining 12 items: Flexibility in Thinking (χ2 = 12.98, P = 0.37) and Structured Memory (χ2 = 8.74, P = 0.72). The 'Diagnostic Thinking Inventory for Optometry Short' (DTI-OS) tool was formed from these items with the total and subdomain scores exhibiting strong internal reliability; Total score Cα = 0.92. External reliability was established by test-retest methodology (ICC 0.92, 95% CI 0.83-0.96, P < .001) and stacked Rasch analysis (one-way ANOVA, F = 0.07, P = 0.80). Qualified optometrists scored significantly higher (P < .001) than students, demonstrating construct validity. CONCLUSION: This study showed that the DTI-O and DTI-OS are valid and reliable self-reflective inventories to quantify diagnostic reasoning ability in optometry. With no other validated tool to measure this metacognitive skill underpinning diagnostic reasoning a self-reflective inventory could support the development of diagnostic reasoning in practitioners and guide curriculum design in optometry education.

Prevalence of myopia among urban and suburban school children in Tamil Nadu, South India: findings from the Sankara Nethralaya Tamil Nadu Essilor Myopia (STEM) Study.

PURPOSE: To report the baseline prevalence of myopia among school children in Tamil Nadu, South India from a prospective cohort study. METHODS: Children between the ages of 5 and 16 years from 11 schools in two districts of Tamil Nadu underwent vision screening. All children underwent visual acuity assessment using a Pocket Vision Screener followed by non-cycloplegic open-field autorefraction (Grand Seiko WAM-5500). Myopia was defined as a spherical equivalent (SE) refraction of ≤-0.75 D and high myopia was defined as SE ≤ -6.00 D. Distribution of refraction, biometry and factors associated with prevalence of myopia were the outcome measures. RESULTS: A total of 14,699 children completed vision screening, with 2% (357) of them having ocular abnormalities other than refractive errors or poor vision despite spectacle correction. The remaining 14,342 children (7557 boys; 52.69%) had a mean age of 10.2 (Standard Deviation [SD] 2.8) years. A total of 2502 had myopia in at least one eye, a prevalence of 17.5% (95% CI: 14.7-20.5%), and 74 (0.5%; 95% CI: 0.3-0.9%) had high myopia. Myopia prevalence increased with age (p < 0.001), but sex was not associated with myopia prevalence (p = 0.24). Mean axial length (AL; 23.08 (SD = 0.91) mm) and mean anterior chamber depth (ACD; 3.45 (SD = 0.27) mm) positively correlated with age (p < 0.001). The mean flat (K1; 43.37 (SD = 1.49) D) and steep (K2; 44.50 (SD = 1.58) D) corneal curvatures showed negative correlation with age (p = 0.02 and p < 0.001, respectively). In the multivariable logistic regression, older age and urban school location had higher odds for prevalence of myopia. CONCLUSION: The baseline prevalence of myopia among 5- to 16-year-old children in South India is larger than that found in previous studies, indicating that myopia is becoming a major public health problem in this country.

The Sankara Nethralaya Tamil Nadu Essilor Myopia (STEM) Study-Defining a Threshold for Non-Cycloplegic Myopia Prevalence in Children.

The aim of this study was to investigate the agreement between cycloplegic and non-cycloplegic autorefraction with an open-field auto refractor in a school vision screening set up, and to define a threshold for myopia that agrees with the standard cycloplegic refraction threshold. The study was conducted as part of the Sankara Nethralaya Tamil Nadu Essilor Myopia (STEM) study, which investigated the prevalence, incidence, and risk factors for myopia among children in South India. Children from two schools aged 5 to 15 years, with no ocular abnormalities and whose parents gave informed consent for cycloplegic refraction were included in the study. All the children underwent visual acuity assessment (Pocket Vision Screener, Elite school of Optometry, India), followed by non-cycloplegic and cycloplegic (1% tropicamide) open-field autorefraction (Grand Seiko, WAM-5500). A total of 387 children were included in the study, of whom 201 were boys. The mean (SD) age of the children was 12.2 (±2.1) years. Overall, the mean difference between cycloplegic and non-cycloplegic spherical equivalent (SE) open-field autorefraction measures was 0.34 D (limits of agreement (LOA), 1.06 D to -0.38 D). For myopes, the mean difference between cycloplegic and non-cycloplegic SE was 0.13 D (LOA, 0.63D to -0.36D). The prevalence of myopia was 12% (95% CI, 8% to 15%) using the threshold of cycloplegic SE ≤ -0.50 D, and was 14% (95% CI, 11% to 17%) with SE ≤ -0.50 D using non-cycloplegic refraction. When myopia was defined as SE of ≤-0.75 D under non-cycloplegic conditions, there was no difference between cycloplegic and non-cycloplegic open-field autorefraction prevalence estimates (12%; 95% CI, 8% to 15%; p = 1.00). Overall, non-cycloplegic refraction underestimates hyperopia and overestimates myopia; but for subjects with myopia, this difference is minimal and not clinically significant. A threshold of SE ≤ -0.75 D agrees well for the estimation of myopia prevalence among children when using non-cycloplegic refraction and is comparable with the standard definition of cycloplegic myopic refraction of SE ≤ -0.50 D.

Multifocal Orthokeratology versus Conventional Orthokeratology for Myopia Control: A Paired-Eye Study.

We conducted a prospective, paired-eye, investigator masked study in 30 children with myopia (-1.25 D to -4.00 D; age 10 to 14 years) to test the efficacy of a novel multifocal orthokeratology (MOK) lens compared to conventional orthokeratology (OK) in slowing axial eye growth. The MOK lens molded a center-distance, multifocal surface onto the anterior cornea, with a concentric treatment zone power of +2.50 D. Children wore an MOK lens in one eye and a conventional OK lens in the fellow eye nightly for 18 months. Eye growth was monitored with non-contact ocular biometry. Over 18 months, MOK-treated eyes showed significantly less axial expansion than OK-treated eyes (axial length change: MOK 0.173 mm less than OK; p < 0.01), and inner axial length (posterior cornea to anterior sclera change: MOK 0.156 mm less than OK, p < 0.01). The reduced elongation was constant across different baseline progression rates (range -0.50 D/year to -2.00 D/year). Visual acuity was less in MOK vs. OK-treated eyes (e.g., at six months, MOK: 0.09 ± 0.01 vs. OK: 0.02 ± 0.01 logMAR; p = 0.01). We conclude that MOK lenses significantly reduce eye growth compared to conventional OK lenses over 18 months.

Stakeholder acceptance of digital team-based learning.

Team-Based Learning (TBL) can be associated with administrative processes that are labour intensive. A commercially-available online system offered an opportunity to reduce this burden. The aims of this study were to test the feasibility of integrating digital TBL into health curricula, and to explore the experiences and perspectives of students and educators participating in digital TBL. A prospective mixed methods design was used to survey postgraduate nursing and optometry students (n = 162), and educators (n = 8) at an Australian university. Student and educator perceptions of digital TBL collected were: usability (System Usability Scale); level of student engagement (Student Self-Report of Engagement); and user satisfaction post-participation in digital TBL (Post-Study System Usability Questionnaire). Mean Student Self-Report of Engagement Scores reflected high student engagement with significantly higher levels of engagement reported for digital (x‾=4.16, SD = 0.199) over paper-based (x‾=3.97, SD = 0.267) TBL (p = 0.001). System Usability Scores revealed students (during: x‾ = 72.35, SD = 15.70; post: x‾ = 74.02, SD = 14.00) and educators (x‾=75.0, SD = 15.12) perceived usability of digital TBL to be above average for systems on this scale. Students (x‾=2.40, SD = 0.19) and educators (x‾=2.36, SD = 0.80) were highly satisfied with digital TBL (Post-Study System Usability Questionnaire). High satisfaction and engagement outcomes suggest digital TBL is feasible, efficient, engaging and well accepted by stakeholders.

Is This Mine to Keep? Three-dimensional Printing Enables Active, Personalized Learning in Anatomy.

Understanding orbital anatomy is important for optometry students, but the learning resources available are often fragile, expensive, and accessible only during scheduled classes. Drawing on a constructivist, personalized approach to learning, this study investigated students' perceptions of an alternative learning resource: a three-dimensional (3D) printed model used in an active learning task. A human skull was three-dimensionally scanned and used to produce a 3D printed model for each student. Students actively participated in model creation by tracing suture lines and coloring individual orbital bones during a practical class, then keeping the model for future study. Students' perceptions of the 3D orbital model were examined through a questionnaire: the impact the model had on their learning; perceptions of the 3D orbit compared to traditional resources; and utility of having their own personalized model. The 3D orbit was well received by the student cohort. Participants (n = 69) preferred the 3D orbit as a resource for learning orbital bone anatomy compared to traditional learning resources, believing the model helped them to understand and visualize the spatial relationships of the bones, and that it increased their confidence to apply this knowledge. Overall, the participants liked that they co-created the model, could touch and feel it, and that they had access to it whenever they liked. Three-dimensional printing technology has the potential to enable the creation of effective learning resources that are robust, low-cost and readily accessible to students, and should be considered by anyone wishing to incorporate personalized resources to their multimodal teaching repertoire.

Visually guided eye growth in the squid.

Eyes with refractive error have reduced visual acuity and are rarely found in the wild. Vertebrate eyes possess a visually guided emmetropisation process within the retina which detects the sign of defocus, and regulates eye growth to align the retina at the focal plane of the eye's optical components to avoid the development of refractive error, such as myopia, an increasing problem in humans. However, the vertebrate retina is complex, and it is not known which of the many classes of retinal neurons are involved. We investigated whether the camera-type eye of an invertebrate, the squid, displays visually guided emmetropisation, despite squid eyes having a simple photoreceptor-only retina. We exploited inherent longitudinal chromatic aberration (LCA) to create disparate focal lengths within squid eyes. We found that squid raised under orange light had proportionately longer eyes and more myopic refractions than those raised under blue light, and when switched between wavelengths, eye size and refractive status changed appropriately within a few days. This demonstrates that squid eye growth is visually guided, and suggests that the complex retina seen in vertebrates may not be required for emmetropisation.

Effect of retinal image defocus on the thickness of the human choroid.

PURPOSE: To describe the time-course and amplitude of changes to sub-foveal choroidal thickness (SFCT) induced by imposed hyperopic and myopic retinal defocus and to compare the responses in emmetropic and myopic subjects. METHODS: Twelve East Asian subjects (age: 18-34 years; six were emmetropic and six had myopia between -2.00 and -5.00 dioptres (D)) viewed a distant target (video movie at 6 m) for 60 min on two separate occasions while optical coherence tomography (OCT) images of the choroid were taken in both eyes every 5 min to monitor SFCT. On each occasion, one eye was optimally corrected for distance with a contact lens while the other eye wore a contact lens imposing either 2.00 D hyperopic or 2.00 D myopic retinal defocus. RESULTS: Baseline SFCT in myopic eyes (mean ± S.D.): 256 ± 42 µm was significantly less than in emmetropic eyes (423 ± 62 µm; p < 0.01) and was correlated with magnitude of myopia (-39 µm per dioptre of myopia, R(2) = 0.67: p < 0.01). Repeated measures anova (General Linear Model) analysis revealed that in both subject groups, 2.00 D of myopic defocus caused a rapid increase in SFCT in the defocussed eye (significant by 10 min, increasing to approximately 20 µm within 60 min: p < 0.01), with little change in the control eye. In contrast, 2.00 D of hyperopic defocus caused a decrease in SFCT in the experimental eye (significant by 20-35 min. SFCT decreased by approximately 20 µm within 60 min: p < 0.01) with little change in the control eye. CONCLUSIONS: Small but significant changes in SFCT (5-8%) were caused by retinal defocus. SFCT increased within 10 min of exposure to 2.00 D of monocular myopic defocus, but decreased more slowly in response to 2.00 D of monocular hyperopic defocus. In our relatively small sample we could detect no difference in the magnitude of changes to SFCT caused by defocus in myopic eyes compared to emmetropic eyes.

Influence of periodic vs continuous daily bright light exposure on development of experimental myopia in the chick.

PURPOSE: In children, time spent outdoors has a protective effect against myopia development. In animal models, bright light reduces the development of experimental myopia. This study investigates how an increase in daily light exposure, presented either continuously during the day or periodically at different times of day, influences the development of experimental myopia in the chick. METHODS: Myopia was induced in Cobb Chicks (Gallus domesticus) by monocular deprivation (MD) of form vision with a translucent diffuser for 3 days (from 4 days of age) under a 12:12 light: dark cycle. MD control chicks were exposed to constant 300 lux (n = 11) during the light period. MD treatment groups received either constant 2000 lux (n = 11) during the light period or 300 lux for 10 h with a 2 h period of bright light (10 000 lux), either in the morning (n = 10), midday (n = 10) or evening (n = 10), giving the same total daily light exposure as the 2000 lux group. After 3 days of MD, refractive status, corneal curvature and axial eye dimensions were measured for all eyes under anaesthesia. RESULTS: Myopia in the constant 2000 lux group (-4.94 ± 1.21 D) was significantly less than in the 300 lux control group (-9.73 ± 0.96 D; p = 0.022). However, compared to the 300 lux control group, 2 h periods of 10 000 lux did not produce significant effects on refraction when presented either in the morning (-9.98 ± 0.85; p = 1.00), midday (-8.00 ± 1.26; p = 0.80), or evening (-13.14 ± 1.16 D; p = 0.20), although significantly less myopia was induced in the midday group compared to the evening group (p = 0.018). Orthogonal regression showed that myopia development was matched by changes in vitreous chamber depth (R(2)  = 0.69; p < 0.0001). CONCLUSIONS: In chicks, an increase in daily light exposure continuously during the day is more effective at inhibiting myopia than adding an equivalent dose within a 2 h period of bright light. A weak time-of-day effect also appears to be present in the response to bright light exposure. Our results suggest that future light-based myopia therapies in humans may be more effective if light levels are increased over the whole day, rather than through short periods of bright light exposure.

Peripheral refraction in myopia corrected with spectacles versus contact lenses.

PURPOSE: Previous studies suggest that the refractive status of the peripheral retina can influence the development and progression of myopia. Our aim was to compare peripheral refractions in the same cohort of human eyes corrected with spectacle lenses vs soft contact lenses. METHODS: Ten young adults with moderate to high myopia (-5.00 D to -8.00 D) were investigated. Open-field autorefraction was used to measure on- and off-axis refractions with the eyes in primary gaze, when uncorrected, and when corrected with spectacles and contact lenses. Measures were made every 5° out to 30° horizontally in nasal and temporal retina and analysed as power vectors (M, J(0) , and J(45)). Partial coherence interferometry measures of eye size were also made on-axis and off-axis at 10º and 20º in nasal and temporal retina. RESULTS: Subjects (mean age 24; range 19-29 years) had an average on-axis mean-sphere refraction of -6.33 ± 0.31 D (mean ± 1 S.E.) and an average axial eye length of 25.99 ± 0.20 mm. The average relative peripheral refraction (RPR) for all subjects across all eccentricities was hyperopic when uncorrected (+0.90 ± 0.14 D) and also when corrected with spectacles (+1.01 ± 0.13 D) but changed to a myopic RPR when corrected with contact lenses (-1.84 ± 0.61 D). There was a highly significant effect of correction on peripheral refraction (p < 0.0001). Peripheral J(0) astigmatism also became significantly more negative (less with-the-rule) on correction with contact lenses (p = 0.015), whereas J(45) astigmatism remained unchanged. On- and off- axis eye length measures indicated a relatively prolate eye shape. CONCLUSIONS: Correcting the on-axis refractive error in moderate to high myopia with conventional spherical spectacle lenses results in hyperopic defocus in the peripheral retina. Correcting the same eyes with conventional spherical soft contact lenses results in significant myopic defocus in the peripheral retina. These results corroborate the general findings of earlier studies and the predictions of optical modelling by others. If the refractive status of the peripheral retina does influence myopia progression, then these results suggest that myopia progression should be slower with conventional contact lens wear than with conventional spectacle wear. However, previous studies comparing myopia progression with conventional spectacles and conventional contact lenses have reported no such difference.

Peripheral refraction in high myopia with spherical soft contact lenses.

PURPOSE: Previous studies suggest that the refractive status of the peripheral retina may influence the progression of myopia. Our aim was to investigate peripheral refractions in human eyes with high myopia when corrected with a conventional soft spherical contact lens (CL). METHODS: Ten young adults with high myopia (over -6.00 D) were investigated. An open-field auto-refractor was used to measure on- and off-axis refractions in primary gaze, with and without a CL, every 5° out to 20° horizontally in nasal and temporal retina. Results were analyzed as mean sphere (M) and astigmatic (J(0) and J(45)) vector components. Partial coherence interferometry measures of eye size were also made on- and off-axis at 10 and 20° in nasal and temporal retina. RESULTS: Subjects (mean age, 22 years; range, 20 to 26 years) had an average on-axis spherical refractive error of -8.31 ± 2.10 D and an average on-axis eye length of 27.39 ± 1.18 mm. Mean sphere exhibited a significant shift from hyperopic relative peripheral refraction (RPR) in the uncorrected state to myopic RPR on correction, in both nasal and temporal retina. Mean RPR of all subjects across all eccentricities was hyperopic when uncorrected (M = +0.20 ± 0.49 D: mean ± 1 SEM) becoming myopic when corrected (M = -0.45 ± 0.56 D: p = 0.0003, reaching -1.21 ± 0.82 D at 20° in the temporal retina). Peripheral J(0) astigmatism also became significantly more negative on correction (p = 0.002), whereas J(45) astigmatism remained unchanged. On- and off-axis measures of eye length indicated a relatively prolate retinal contour. Uncorrected off-axis mean sphere refractive error reduced with eccentricity, and this was accurately predicted (R > 0.98) by the measured retinal contour. CONCLUSIONS: Correcting the foveal refractive error in high myopia with standard spherical soft CLs can result in significant absolute myopic defocus in the peripheral retina. If peripheral refraction does indeed influence myopia progression, then our results suggest that in high myopia, standard soft CLs may be beneficial in reducing myopia progression.

Effect of induced myopia on scleral myofibroblasts and in vivo ocular biomechanical compliance in the guinea pig.

PURPOSE: To examine the effect of induced myopia on scleral myofibroblast populations and in vivo ocular biomechanical compliance. METHODS: One-week-old guinea pigs were monocularly deprived (MD) of form vision for 2 weeks. Ocular biomechanical compliance was measured in both eyes of anesthetized animals by increasing the intraocular pressure (IOP) to 50 mm Hg for 1 hour, while A-scan ultrasound measures were made every 10 minutes to investigate the change in axial length. The total cell population and myofibroblast subpopulation of the posterior 100° of the sclera was determined with immunohistochemical techniques. RESULTS: The vitreous chamber depth (VCD) of MD and contralateral control eyes showed significant elastic expansion on increasing the IOP, compared with that of the nonmanipulated normal eyes. The creep response of the VCD in response to increased IOP was initially greater in the normal eyes until eye length was similar to the MD and control eyes. An unexpectedly high proportion of the scleral cell population were myofibroblasts (63.7% ± 1.7%, average ± SEM; n = 30). MD significantly decreased the total number of cells in the region between the optic nerve and 10° nasal (equivalent to myopic crescent location in humans) compared with the number in control or normal eyes, but no significant effect on myofibroblasts or the total number of cells was found elsewhere. CONCLUSIONS: A high proportion of scleral cells have contractile potential. This proportion is unaffected by MD. However, there is a significant difference in the in vivo elastic response of the sclera between MD and normal eyes, suggesting that factors other than number of cells have an effect on axial length.