Link between parental myopia and early-onset high myopia: Insights from a clinical retrospective analysis.

INTRODUCTION: Genetic aetiology is suspected in the development of early-onset high myopia (spherical equivalent refractive error [SER] ≤-6.00 D at ≤6 years of age), considering that the role of environmental factors in inducing high myopia is improbable at an early age. Therefore, we aimed to understand if early-onset high myopia is associated with parental myopia in a clinical setting. METHODS: A retrospective study was conducted in which information about demographics, age of apparent onset of myopia, refractive error, axial length, number of myopic parents, time spent outdoors and time spent on near-work was obtained from electronic medical records (EMR). It included 195 myopic individuals categorised into (1) Early-onset high myopes (EOHM): SER ≤ -6.00 D with age of presentation ≤6 years, (2) Early-onset low myopes (EOLM): SER > -6.00 D with age of apparent onset ≤6 years, (3) Late-onset high myopes (LOHM): SER ≤ -6.00 D with age of presentation and age of apparent onset >6 years and (4) Late-onset low myopes (LOLM): SER > -6.00 D with age of apparent onset >6 years. RESULTS: Overall, 63% of individuals were found to have parental myopia. The proportion of individuals with EOHM, EOLM, LOHM and LOLM with parental myopia was 57%, 74%, 53% and 64%, respectively. After adjustment for age, gender and environmental factors, the odds of development of EOHM (Odds ratio: 0.78, 95% confidence interval: 0.25-2.48), EOLM (1.54, 0.65-3.67) or LOHM (0.70, 0.30-1.65) were similar in the presence of myopic parents, when compared with LOLM. The SER and axial length did not differ based on the number of myopic parents in any of these categories. CONCLUSION: This retrospective analysis reveals that the presence of parental myopia, which was self-reported, did not induce additional risk for early-onset high myopia.

Interventions for myopia control in children: a living systematic review and network meta-analysis.

BACKGROUND: Myopia is a common refractive error, where elongation of the eyeball causes distant objects to appear blurred. The increasing prevalence of myopia is a growing global public health problem, in terms of rates of uncorrected refractive error and significantly, an increased risk of visual impairment due to myopia-related ocular morbidity. Since myopia is usually detected in children before 10 years of age and can progress rapidly, interventions to slow its progression need to be delivered in childhood. OBJECTIVES: To assess the comparative efficacy of optical, pharmacological and environmental interventions for slowing myopia progression in children using network meta-analysis (NMA). To generate a relative ranking of myopia control interventions according to their efficacy. To produce a brief economic commentary, summarising the economic evaluations assessing myopia control interventions in children. To maintain the currency of the evidence using a living systematic review approach.  SEARCH METHODS: We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register), MEDLINE; Embase; and three trials registers. The search date was 26 February 2022.  SELECTION CRITERIA: We included randomised controlled trials (RCTs) of optical, pharmacological and environmental interventions for slowing myopia progression in children aged 18 years or younger. Critical outcomes were progression of myopia (defined as the difference in the change in spherical equivalent refraction (SER, dioptres (D)) and axial length (mm) in the intervention and control groups at one year or longer) and difference in the change in SER and axial length following cessation of treatment ('rebound').  DATA COLLECTION AND ANALYSIS: We followed standard Cochrane methods. We assessed bias using RoB 2 for parallel RCTs. We rated the certainty of evidence using the GRADE approach for the outcomes: change in SER and axial length at one and two years. Most comparisons were with inactive controls. MAIN RESULTS: We included 64 studies that randomised 11,617 children, aged 4 to 18 years. Studies were mostly conducted in China or other Asian countries (39 studies, 60.9%) and North America (13 studies, 20.3%). Fifty-seven studies (89%) compared myopia control interventions (multifocal spectacles, peripheral plus spectacles (PPSL), undercorrected single vision spectacles (SVLs), multifocal soft contact lenses (MFSCL), orthokeratology, rigid gas-permeable contact lenses (RGP); or pharmacological interventions (including high- (HDA), moderate- (MDA) and low-dose (LDA) atropine, pirenzipine or 7-methylxanthine) against an inactive control. Study duration was 12 to 36 months. The overall certainty of the evidence ranged from very low to moderate. Since the networks in the NMA were poorly connected, most estimates versus control were as, or more, imprecise than the corresponding direct estimates. Consequently, we mostly report estimates based on direct (pairwise) comparisons below. At one year, in 38 studies (6525 participants analysed), the median change in SER for controls was -0.65 D. The following interventions may reduce SER progression compared to controls: HDA (mean difference (MD) 0.90 D, 95% confidence interval (CI) 0.62 to 1.18), MDA (MD 0.65 D, 95% CI 0.27 to 1.03), LDA (MD 0.38 D, 95% CI 0.10 to 0.66), pirenzipine (MD 0.32 D, 95% CI 0.15 to 0.49), MFSCL (MD 0.26 D, 95% CI 0.17 to 0.35), PPSLs (MD 0.51 D, 95% CI 0.19 to 0.82), and multifocal spectacles (MD 0.14 D, 95% CI 0.08 to 0.21). By contrast, there was little or no evidence that RGP (MD 0.02 D, 95% CI -0.05 to 0.10), 7-methylxanthine (MD 0.07 D, 95% CI -0.09 to 0.24) or undercorrected SVLs (MD -0.15 D, 95% CI -0.29 to 0.00) reduce progression.  At two years, in 26 studies (4949 participants), the median change in SER for controls was -1.02 D. The following interventions may reduce SER progression compared to controls: HDA (MD 1.26 D, 95% CI 1.17 to 1.36), MDA (MD 0.45 D, 95% CI 0.08 to 0.83), LDA (MD 0.24 D, 95% CI 0.17 to 0.31), pirenzipine (MD 0.41 D, 95% CI 0.13 to 0.69), MFSCL (MD 0.30 D, 95% CI 0.19 to 0.41), and multifocal spectacles  (MD 0.19 D, 95% CI 0.08 to 0.30). PPSLs (MD 0.34 D, 95% CI -0.08 to 0.76) may also reduce progression, but the results were inconsistent. For RGP, one study found a benefit and another found no difference with control. We found no difference in SER change for undercorrected SVLs (MD 0.02 D, 95% CI -0.05 to 0.09). At one year, in 36 studies (6263 participants), the median change in axial length for controls was 0.31 mm. The following interventions may reduce axial elongation compared to controls: HDA (MD -0.33 mm, 95% CI -0.35 to 0.30), MDA (MD -0.28 mm, 95% CI -0.38 to -0.17), LDA (MD -0.13 mm, 95% CI -0.21 to -0.05), orthokeratology (MD -0.19 mm, 95% CI -0.23 to -0.15), MFSCL (MD -0.11 mm, 95% CI -0.13 to -0.09), pirenzipine (MD -0.10 mm, 95% CI -0.18 to -0.02), PPSLs (MD -0.13 mm, 95% CI -0.24 to -0.03), and multifocal spectacles (MD -0.06 mm, 95% CI -0.09 to -0.04). We found little or no evidence that RGP (MD 0.02 mm, 95% CI -0.05 to 0.10), 7-methylxanthine (MD 0.03 mm, 95% CI -0.10 to 0.03) or undercorrected SVLs (MD 0.05 mm, 95% CI -0.01 to 0.11) reduce axial length. At two years, in 21 studies (4169 participants), the median change in axial length for controls was 0.56 mm. The following interventions may reduce axial elongation compared to controls: HDA (MD -0.47mm, 95% CI -0.61 to -0.34), MDA (MD -0.33 mm, 95% CI -0.46 to -0.20), orthokeratology (MD -0.28 mm, (95% CI -0.38 to -0.19), LDA (MD -0.16 mm, 95% CI -0.20 to  -0.12), MFSCL (MD -0.15 mm, 95% CI -0.19 to -0.12), and multifocal spectacles (MD -0.07 mm, 95% CI -0.12 to -0.03). PPSL may reduce progression (MD -0.20 mm, 95% CI -0.45 to 0.05) but results were inconsistent. We found little or no evidence that undercorrected SVLs (MD -0.01 mm, 95% CI -0.06 to 0.03) or RGP (MD 0.03 mm, 95% CI -0.05 to 0.12) reduce axial length. There was inconclusive evidence on whether treatment cessation increases myopia progression. Adverse events and treatment adherence were not consistently reported, and only one study reported quality of life. No studies reported environmental interventions reporting progression in children with myopia, and no economic evaluations assessed interventions for myopia control in children. AUTHORS' CONCLUSIONS: Studies mostly compared pharmacological and optical treatments to slow the progression of myopia with an inactive comparator. Effects at one year provided evidence that these interventions may slow refractive change and reduce axial elongation, although results were often heterogeneous. A smaller body of evidence is available at two or three years, and uncertainty remains about the sustained effect of these interventions. Longer-term and better-quality studies comparing myopia control interventions used alone or in combination are needed, and improved methods for monitoring and reporting adverse effects.

ANTECEDENTES: La miopía es un defecto de refracción frecuente, en el que el alargamiento del globo ocular hace que los objetos lejanos aparezcan borrosos. La creciente prevalencia de la miopía es un problema de salud pública mundial cada vez mayor, en cuanto a tasas de defectos de refracción no corregidos y un significativamente mayor riesgo de discapacidad visual debido a la morbilidad ocular relacionada con la miopía. Dado que la miopía se suele detectar en niños antes de los 10 años y puede evolucionar rápidamente, las intervenciones para frenar su avance se deben realizar en la infancia. OBJETIVOS: Evaluar la eficacia comparativa de las intervenciones ópticas, farmacológicas y ambientales para frenar la progresión de la miopía en niños mediante un metanálisis en red (MAR). Generar una clasificación relativa de las intervenciones de control de la miopía en función de su eficacia. Elaborar un breve comentario económico que resuma las evaluaciones económicas de las intervenciones de control de la miopía en niños. Mantener la vigencia de la evidencia mediante un enfoque de revisión sistemática continua. MÉTODOS DE BÚSQUEDA: Se realizaron búsquedas en CENTRAL (que contiene el Registro de ensayos del Grupo Cochrane de Salud ocular y de la visión [Cochrane Eyes and Vision]), MEDLINE; Embase; y en tres registros de ensayos. La fecha de búsqueda fue el 26 de febrero de 2022. CRITERIOS DE SELECCIÓN: Se incluyeron ensayos controlados aleatorizados (ECA) de intervenciones ópticas, farmacológicas y ambientales para retrasar la progresión de la miopía en niños de hasta 18 años. Los desenlaces fundamentales fueron la progresión de la miopía (definida como la diferencia en el cambio del equivalente esférico de la refracción [EER, dioptrías (D)] y la longitud axial [mm] en los grupos de intervención y control al año o más) y la diferencia en el cambio del EER y la longitud axial tras el cese del tratamiento ("rebote"). OBTENCIÓN Y ANÁLISIS DE LOS DATOS: Se utilizaron los métodos Cochrane estándar. El sesgo se evaluó mediante la herramienta RoB 2 en el caso de los ECA paralelos. La certeza de la evidencia se calificó mediante el método GRADE para los desenlaces: cambio del EER y la longitud axial al año y a los dos años. La mayoría de las comparaciones se realizaron con controles inactivos. RESULTADOS PRINCIPALES: Se incluyeron 64 estudios que asignaron al azar a 11 617 niños de cuatro a 18 años de edad. Los estudios se realizaron principalmente en China u otros países asiáticos (39 estudios; 60,9%) y Norteamérica (13 estudios; 20,3%). Cincuenta y siete estudios (89%) compararon intervenciones de control de la miopía (gafas multifocales, gafas periféricas plus [PPSL por sus siglas en inglés], gafas monofocales [SVL por sus siglas en inglés] subcorregidas, lentes de contacto multifocales blandas [MFSCL por sus siglas en inglés], ortoqueratología, lentes de contacto rígidas permeables al gas [RGP por sus siglas en inglés]); o intervenciones farmacológicas (incluidas atropina a dosis alta, media y baja, pirenzipina o 7­metilxantina) contra un control inactivo. La duración de los estudios fue de 12 a 36 meses. La certeza global de la evidencia varió entre muy baja y moderada. Debido a que las redes del MAR estaban mal conectadas, la mayoría de las estimaciones versus control fueron tan imprecisas o más que las correspondientes estimaciones directas. En consecuencia, a continuación se presentan principalmente estimaciones basadas en comparaciones directas (por pares). Al año, en 38 estudios (6525 participantes analizados), la mediana del cambio del EER para los controles fue de ­0,65 D. Las siguientes intervenciones podrían reducir la progresión del EER en comparación con los controles: atropina a dosis alta (diferencia de medias [DM] 0,90 D; intervalo de confianza [IC] del 95%: 0,62 a 1,18), atropina a dosis media (DM 0,65 D; IC del 95%: 0,27 a 1,03), atropina a dosis baja (DM 0,38 D; IC del 95%: 0,10 a 0,66), pirenzipina (DM 0,32 D; IC del 95%: 0,15 a 0,49), MFSCL (DM 0,26 D; IC del 95%: 0,17 a 0,35), PPSL (DM 0,51 D; IC del 95%: 0,19 a 0,82) y gafas multifocales (DM 0,14 D; IC del 95%: 0,08 a 0,21). Por el contrario, hubo poca o ninguna evidencia de que las RGP (DM 0,02 D; IC del 95%: ­0,05 a 0,10), la 7­metilxantina (DM 0,07 D; IC del 95%: ­0,09 a 0,24) o las SVL subcorregidas (DM ­0,15 D; IC del 95%: ­0,29 a 0,00) redujeran la progresión. A los dos años, en 26 estudios (4949 participantes), el cambio medio del EER para los controles fue de ­1,02 D. Las siguientes intervenciones podrían reducir la progresión del EER en comparación con los controles: atropina a dosis alta (DM 1,26 D; IC del 95%: 1,17 a 1,36), atropina a dosis media (DM 0,45 D; IC del 95%: 0,08 a 0,83), atropina a dosis baja (DM 0,24 D; IC del 95%: 0,17 a 0,31), pirenzipina (DM 0,41 D; IC del 95%: 0,13 a 0,69), MFSCL (DM 0,30 D; IC del 95%: 0,19 a 0,41) y gafas multifocales (DM 0,19 D; IC del 95%: 0,08 a 0,30). Las PPSL (DM 0,34 D; IC del 95%: ­0,08 a 0,76) también podrían reducir la progresión, pero los resultados no fueron consistentes. Para las RGP, un estudio encontró un efecto beneficioso y otro no encontró diferencias con el control. No se observaron diferencias en el cambio del EER para las SVL subcorregidas (DM 0,02 D; IC del 95%: ­0,05 a 0,09). Al año, en 36 estudios (6.263 participantes), el cambio medio en la longitud axial de los controles fue de 0,31 mm. Las siguientes intervenciones podrían reducir la elongación axial en comparación con los controles: atropina a dosis alta (DM ­0,33 mm; IC 95%: ­0,35 a 0,30), atropina a dosis media (DM ­0,28 mm; IC 95%: ­0,38 a ­0,17), atropina a dosis baja (DM ­0,13 mm; IC 95%: ­0,21 a ­0,05), ortoqueratología (DM ­0,19 mm; IC 95%: ­0,23 a ­0,15), MFSCL (DM ­0,11 mm; IC del 95%: ­0,13 a ­0,09), pirenzipina (DM ­0,10 mm; IC del 95%: ­0,18 a ­0,02), PPSL (DM ­0,13 mm; IC del 95%: ­0,24 a ­0,03) y gafas multifocales (DM ­0,06 mm; IC del 95%: ­0,09 a ­0,04). Se encontró poca o ninguna evidencia de que las RGP (DM 0,02 mm; IC del 95%: ­0,05 a 0,10), la 7­metilxantina (DM 0,03 mm; IC del 95%: ­0,10 a 0,03) o las SVL subcorregidas (DM 0,05 mm; IC del 95%: ­0,01 a 0,11) reduzcan la longitud axial. A los dos años, en 21 estudios (4169 participantes), la mediana del cambio en la longitud axial de los controles fue de 0,56 mm. Las siguientes intervenciones podrían reducir la elongación axial en comparación con los controles: atropina a dosis alta (DM ­0,47 mm; IC del 95%: ­0,61 a ­0,34), atropina a dosis media (DM ­0,33 mm; IC del 95%: ­0,46 a ­0,20), ortoqueratología (DM ­0,28 mm; IC del 95%: ­0,38 a ­0,19), atropina a dosis baja (DM ­0,16 mm; IC del 95%: ­0,20 a ­0,12), MFSCL (DM ­0,15 mm; IC del 95%: ­0,19 a ­0,12) y gafas multifocales (DM ­0,07 mm; IC del 95%: ­0,12 a ­0,03). Las PPSL podrían reducir la progresión (DM ­0,20 mm; IC del 95%: ­0,45 a 0,05), pero los resultados no fueron consistentes. Se encontró poca o ninguna evidencia de que las SVL subcorregidas (DM ­0,01 mm; IC del 95%: ­0,06 a 0,03) o las RGP (DM 0,03 mm; IC del 95%: ­0,05 a 0,12) reduzcan la longitud axial. No hubo evidencia concluyente sobre si el abandono del tratamiento aumenta la progresión de la miopía. Los eventos adversos y la adherencia al tratamiento no se comunicaron de forma consistente, y solo un estudio informó sobre la calidad de vida. Ningún estudio proporcionó información sobre intervenciones ambientales que informaran sobre la progresión en niños con miopía y ninguna evaluación económica analizó intervenciones para el control de la miopía en niños. CONCLUSIONES DE LOS AUTORES: La mayoría de los estudios compararon tratamientos farmacológicos y ópticos para enlentecer la progresión de la miopía con un comparador inactivo. Los efectos al año demostraron que estas intervenciones podrían ralentizar el cambio refractivo y reducir el alargamiento axial, aunque a menudo los resultados fueron heterogéneos. El conjunto de evidencia disponible a los dos o tres años fue más escaso, y persiste la incertidumbre sobre el efecto sostenido de estas intervenciones. Se necesitan estudios a más largo plazo y de mejor calidad que comparen las intervenciones para el control de la miopía utilizadas solas o en combinación, así como métodos mejorados de seguimiento y notificación de los efectos adversos.

Accuracy and Precision of New Optical Biometer Designed for Myopia Management in Measurement of Ocular Biometry.

SIGNIFICANCE: This study provides information about the repeatability of Myopia Master (Oculus, Wetzlar, Germany) and its agreement with Lenstar LS900, which might be useful for the practitioners involved in myopia management. PURPOSE: Myopia Master is a new optical biometer that measures ocular biometry and refractive error. The purpose of this study was to assess its repeatability (intrasession and short-term intersession) and its agreement with Lenstar LS900 for the measurement of axial length and corneal curvature. METHODS: A total of 304 participants including 254 children (mean ± standard deviation age, 13.7 ± 1.6 years) and 50 adults (24 ± 2.9 years) underwent measurements on Myopia Master and Lenstar LS900 to obtain axial length, flat K, and steep K. On a subset of 30 participants, measurements were obtained with Myopia Master in two sessions that were spread over 10 minutes to assess the short-term intersession repeatability. RESULTS: The mean standard deviation of Myopia Master in the measurement of axial length in the total sample was 0.01 mm for intrasession, when the best three measurements were considered. The short-term intersession mean standard deviation for axial length, flat K, and steep K was 0.06 mm, 0.15 D, and 0.21 D, respectively. There were statistically significant differences in mean values of axial length (-0.04 ± 0.06 mm), flat K (-0.07 ± 0.15 D), and steep K (-0.24 ± 0.29 D) between Lenstar LS900 and Myopia Master, with the Lenstar providing slightly longer axial length and steeper K values. Adults showed better repeatability with Myopia Master and better agreement between the biometers for axial length measurement than children. Neither axial length nor refractive error influenced the repeatability or agreement. CONCLUSIONS: Myopia Master is repeatable for the measurement of axial length and corneal curvature. Considering the differences in axial length between the Myopia Master and Lenstar LS900, caution must be applied when these biometers are used interchangeably.

Do Anisometropic Eyes Have Steeper Retinas Than Their Isometropic Counterparts?

SIGNIFICANCE: Our findings suggest that retinal shapes of the eyes of anisometropes are not different from that of the eyes of isometropes with the same refractions. PURPOSE: We investigated ( a ) intereye differences in relative peripheral eye lengths between isometropes and anisometropes and ( b ) if the retinal shape is different between isometropic and anisometropic eyes with the same central refraction. METHODS: Central and peripheral eye lengths were determined along the horizontal meridian in 10° intervals out to ±30° using a noncontact biometer in 28 isometropes and 16 anisometropes. Retinal coordinates were estimated using these eye lengths and ray tracing. Retinal shape was determined in terms of vertex radius of curvature ( Rv ), asphericity ( Q ), and equivalent radius of curvature ( REq ). Linear regression was determined for the REq as functions of central refraction in a subset of isometropic and anisometropic eyes having the same refraction. RESULTS: The differences in relative peripheral eye lengths between the two eyes of anisometropes were significantly greater than for isometropes at ±30° eccentricities. Higher myopic eyes of anisometropes had smaller Rv , more negative Q , and smaller REq than the lower myopic eyes for both isometropes and anisometropes (mean ± standard error of the mean: Rv , 9.8 ± 0.5 vs. 11.7 ± 0.4 mm [ P = .002]; Q , -1.1 ± 0.2 vs. -0.5 ± 0.2 [ P = .03]; REq , 11.5 ± 0.3 vs. 12.4 ± 0.2 mm [ P = .01]). Intercepts and slopes of the linear regressions of REq in anisometropes and their isometropic counterparts with the same refraction were not significantly different from each other ( P > .05). CONCLUSIONS: Higher myopic eyes of anisometropes had similar retina shapes along the horizontal meridian to those of isometropic eyes with the same refraction.

Is There Any Association between Nutrition and Myopia? A Systematic Review.

SIGNIFICANCE: This systematic review highlights the possible role of nutrition in myopia based on qualitative analysis of vast and diverse literature that investigated this association. PURPOSE: We systematically reviewed the outcomes of the studies that previously investigated the association between nutrition and myopia. METHODS: EMBASE, MEDLINE, and PubMed were searched by two independent authors to identify cross-sectional, cohort, retrospective, or interventional studies that assessed the association of nutrition with myopia from inception to the year 2021. Furthermore, the reference list of the included articles was screened. The data from the included studies were extracted, and qualitative analysis was performed. Quality assessment for noninterventional studies and interventional trials was performed using the Newcastle-Ottawa Scale and Cochrane RoB 2, respectively. RESULTS: Twenty-seven articles were included in the review. Most of the nutrients and dietary elements investigated in noninterventional studies showed inconsistencies in their association with myopia, with the majority indicating no association. Nine studies showed a significant association of diverse nutrients and dietary elements with either an increase (odds ratio, 1.07) or a decrease (odds ratio, 0.5 to 0.96) in the risk of myopia development. However, a majority of these studies have minimal odds ratios with wider or overlapping confidence intervals, implicating weaker associations. All three nutrients and dietary elements assessed in the interventional trial had implications for myopia control, with two trials indicating a clinically minimal effect. CONCLUSIONS: This review implies that there is some evidence to indicate a potential influence of specific nutrients and dietary elements in myopia development, which are supported by several theories. However, given the vast, diverse, and complex nature of nutrition, more systematic investigation is warranted to comprehend the extent to which these specific nutrients and dietary elements are associated with myopia through longitudinal studies by subduing the limitations in the existing literature.

Near work, light levels and dioptric profile - Which factor dominates and influences the short-term changes in axial length?

PURPOSE: Given the agonistic nature of near work to promote axial elongation and the antagonistic nature of time outdoors to prevent myopia, we aimed to investigate the following: (a) how the short-term effect of near work performed outdoors (Experiment 1) influences axial length and (b) how near work performed in two different dioptric profiles (uncluttered and cluttered) alters the changes in central axial length (Experiment 2). METHODS: Forty-six adults (age range: 19-32 years) participated in the study. In Experiment 1, 22 participants completed a 15-min distance task and a reading task in both the outdoor (~30,000 lux) and indoor (~70 lux) locations. In Experiment 2, 24 participants performed the same reading task at a study desk in uncluttered and cluttered reading environments. Pre- and post-task ocular biometry measurements were performed for each session using a non-contact biometer. RESULTS: In Experiment 1, a significant increase in axial length from baseline was found after performing reading tasks in both outdoor (mean ± SEM: +12.3 ± 3.4 µm, p = 0.001) and indoor locations (+11.9 ± 3.1 µm, p = 0.001). In Experiment 2, axial length increased significantly from baseline to post reading task, in both uncluttered (+17.9 ± 3.5 µm, p < 0.001) and cluttered reading environments (+19.2 ± 2.9 µm, p < 0.001). No significant changes in axial length were observed either between outdoor and indoor locations (p = 0.92) or between the uncluttered and cluttered reading environment (p = 0.75). CONCLUSION: Independent of light intensity (outdoor or indoor location) and dioptric profile of the near-work environment (uncluttered or cluttered), a 15-min reading task led to a significant increase in axial length. While the long-term effects of these findings need to be evaluated, practitioners should emphasise how near work can reduce the beneficial effects of time outdoors, while providing recommendations related to time outdoors for myopia control.

Influence of location, season and time of day on the spectral composition of ambient light: Investigation for application in myopia.

PURPOSE: Given the possible role of spectral composition of light and myopia, this study aimed at investigating the variation in the spectral composition of ambient light in different (a) outdoor/indoor locations, (b) time of a day and (c) seasons. METHODS: The spectral power distribution (SPD), categorised into short (380-500 nm), middle (505-565 nm) and long wavelengths (625-780 nm), was recorded using a handheld spectrometer at three outdoor locations ('open playground', 'under shade of tree' and 'canopy') and three indoor locations ('room with multiple windows', 'closed room' and 'closed corridor'). Readings were taken at five different time points (3-h intervals between 6:30 and 18:00 hours) on two days, each during the summer and monsoon seasons. RESULTS: The overall median SPD (IQR [25th-75th percentile] W/nm/m2 ) across the three outdoor locations (0.11 [0.09, 0.12]) was 157 times higher than that of the indoor locations (0.0007 [0.0001, 0.001]). Considerable locational, diurnal and seasonal variation was observed in the distribution of the median SPD value, with the highest value being recorded in the 'open playground' (0.27 [0.21, 0.28]) followed by 'under shade of tree' (0.083 [0.074, 0.09]), 'canopy' (0.014 [0.012, 0.015]) and 'room with multiple windows' (0.023 [0.015, 0.028]). The relative percentage composition of short, middle and long wavelengths was similar in both the outdoor and indoor locations, with the proportion of middle wavelengths significantly higher (p < 0.01) than short and long wavelengths in all the locations, except 'canopy'. CONCLUSION: Irrespective of variation in SPD values with location, time, day and season, outdoor locations always exhibited significantly higher spectral power than indoor locations. The relative percentage composition of short, middle and long wavelengths of light was similar across all locations. These findings establish a foundation for future research to understand the relationship between spectral power and the development of myopia.

Factors associated with reduced visual acuity in myopes with and without ocular pathologies after optical correction.

PURPOSE: Considering that a certain proportion of high myopes have reduced visual acuity even after full optical correction, this study aimed to investigate the association between various refractive error components (sphere, cylinder and axis orientation) and reduced visual acuity in individuals with low to high myopia with and without pathologic myopia lesions. METHODS: We analysed data from randomly selected eyes of 11,258 individuals with myopia (mean ± SD spherical equivalent (SE) -3.2 ± 2.9D; range: -0.5D to -21.5D). In total, 10,528 individuals had no pathologic myopia lesions. Sphere, cylinder and SE refraction were classified into mild, moderate and high categories. Astigmatism was defined as with-the-rule, against-the-rule or oblique based on the axis orientation. Reduced best-corrected visual acuity was defined as ≥0.18 logMAR. Logistic regression was performed to test factors associated with reduced visual acuity with and without pathologic myopia lesions. RESULT: Overall, 6.4% (N = 720/11,258) of myopes had reduced best-corrected visual acuity. High sphere (≤-6.0D; Odd ratios [OR]: 16.1; 95% CI: 2.1-126.5), high cylinder (<-2.0 DC; OR: 2.5; 95% CI: 1.8-3.4), against-the-rule (OR: 1.5; 95% CI: 1.1-2.0) and oblique astigmatism (OR: 1.6; 95% CI: 1.2-2.1) were significantly (p ≤ 0.008) associated with reduced visual acuity in the absence of pathologic myopia lesions. Both moderate SE and high myopic SE were also associated with reduced visual acuity. In the presence of pathologic myopia lesions, tessellated fundus (OR: 6.9; 95% CI: 3.5-14.1), chorioretinal atrophy (OR: 7.7; 95% CI: 2.6-19.9) and choroidal neovascularisation (OR: 37.4; 95% CI: 3.3-419.3) were significantly (p ≤ 0.003) associated with reduced visual acuity. CONCLUSION: Even after full optical correction, both refractive components and pathologic myopia lesions can independently cause reduced visual acuity, regardless of the degree of myopia.

Development and validation of a 'MyLyt' wearable light tracking device.

PURPOSE: We developed a clip-on light tracker (MyLyt) for estimating light exposure in real time. This study aimed at validating and investigating the feasibility of using MyLyt in children and adults. METHOD: The study was conducted in two phases. Phase 1 involved validation against a factory-calibrated digital lux meter in three separate conditions: controlled environmental set-up, outdoors and indoors where intra-test (two measurements by the same tracker), inter-test (measurements among trackers) and inter-device (MyLyt tracker and lux meter) validations were conducted. Phase 2 involved a feasibility study where MyLyt was used in a real-world setting by 21 adults and 8 children. Participants were asked to log their real-time movements in an 'activity diary', which were correlated with the lux levels measured by the tracker. RESULTS: A strong positive correlation and non-significant difference in the recorded mean illuminance levels were observed during intra-test (inter-class correlation: 1.00, p = 0.99), inter-test (0.91-1.00, p > 0.15) and inter-device (0.91-1.00, p > 0.56) validation in all three testing conditions (p > 0.49), except the indoor location. While the lux level measured by MyLyt was significantly higher than that of the lux meter (p < 0.01) in the indoor locations, differences were minimal and clinically insignificant. A Bland-Altman plot showed a minimal mean difference (95% limits of agreement) between the MyLyt tracker and lux meter in all three conditions (controlled environmental set-up: 641 [-949, 2230], outdoor: 74 [-2772, 2920] and indoor: -35 [-151, 80] lux). Phase 2 validation showed an expected illuminance level against the corresponding location with high sensitivity (97.8%) and specificity (99%) to accurately differentiate between outdoor and indoor locations. CONCLUSION: The MyLyt tracker showed good repeatability, strong correlation and comparable values with the lux meter in the three tested conditions, making it suitable for tracking light exposure patterns for both research and clinical purposes.

Time spent outdoors as an intervention for myopia prevention and control in children: an overview of systematic reviews.

PURPOSE: Outdoor light exposure is considered a safe and effective strategy to reduce myopia development and aligns with existing public health initiatives to promote healthier lifestyles in children. However, it is unclear whether this strategy reduces myopia progression in eyes that are already myopic. This study aims to conduct an overview of systematic reviews (SRs) reporting time spent outdoors as a strategy to prevent myopia or slow its progression in children. METHODS: We searched the Cochrane Library, EMBASE, MEDLINE and CINAHL from inception to 1 November 2020 to identify SRs that evaluated the association between outdoor light exposure and myopia development or progression in children. Outcomes included incident myopia, prevalent myopia and change in spherical equivalent refraction (SER) and axial length (AL) to evaluate annual rates of myopia progression. The methodological quality and risk of bias of included SRs were assessed using the AMSTAR-2 and ROBIS tools, respectively. RESULTS: Seven SRs were identified, which included data from 47 primary studies with 63,920 participants. Pooled estimates (risk or odds ratios) consistently demonstrated that time outdoors was associated with a reduction in prevalence and incidence of myopia. In terms of slowing progression in eyes that were already myopic, the reported annual reductions in SER and AL from baseline were small (0.13-0.17 D) and regarded as clinically insignificant. Methodological quality assessment using AMSTAR-2 found that all reviews had one or more critical flaws and the ROBIS tool identified a low risk of bias in only two of the included SRs. CONCLUSION: This overview found that increased exposure to outdoor light reduces myopia development. However, based on annual change in SER and AL, there is insufficient evidence for a clinically significant effect on myopia progression. The poor methodological quality and inconsistent reporting of the included systematic reviews reduce confidence in the estimates of effect.

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

PURPOSE: We aimed to test the accommodative lag and mechanical tension theories for myopia by assessing the influence of the lag of accommodation on axial elongation by using three different near targets that are known to influence the accommodative response differently. METHODS: Forty-two young adults were recruited for the study. Axial length was measured using a non-contact biometer, before and immediately after a 15 minute visual task, with one of the three near targets placed 20 cm from the eye: reading text from a paper, reading text from a smartphone and watching a video on a smartphone. The accommodative response was determined using an open-field autorefractor while the participants viewed the near target monocularly. RESULTS: Lag of accommodation was significantly different for the three tasks: watching a video (mean ± standard error of the mean [SEM] 0.92 ± 0.10 D); reading text on the smartphone (0.59 ± 0.08 D); and reading text on paper (0.24 ± 0.09 D). There was a significant (p < 0.05) increase in axial length after reading text from a paper (10.5 ± 1.9 µm after 15-min) and reading text from a smartphone (5.2 ± 2.7 µm), but not after watching a video on a smartphone (-0.5 ± 1.7 µm, p = 0.47). Vitreous chamber depth increased significantly more with the reading tasks compared with watching a video (reading text from a paper and smartphone: 33.9 ± 4 µm and 31.7 ± 4 µm vs. watching a video on a smartphone: 14.6 ± 5 µm, p = 0.001). CONCLUSION: Greater changes in axial length associated with the low lag of accommodation failed to support the theory that lag of accommodation during visual tasks could be the trigger for axial elongation. Reading on paper and smartphone at the closest reading distance may stimulate high accommodative demand and axial elongation as a consequence, possibly due to increased "ciliary muscle tension" during accommodation.

Time trends on the prevalence of myopia in India - A prediction model for 2050.

PURPOSE: This study aimed to predict myopia prevalence in urban Indian children and to describe the generational effect of myopia in different age groups over the next three decades from the year 2020. METHODS: A systematic review of myopia prevalence in India was performed using the Preferred Reporting Items for the Systematic Reviews and Meta-analysis (PRISMA) guidelines and included eight studies with 28 600 participants, which were published in the period 1 January 1999 to 31 December 2019. The best fit for the prediction model was assessed with the baseline prevalence data plotted against different years and fitted with multiple mathematical regressions (linear, second-order polynomial, third order polynomial and exponential). Based on the quality of the fit assessed by the coefficient of determination (R2 ) values, the sum of squared residuals and statistical significance, final predictions for myopia prevalence in the 5 to 15-year-old urban Indian children was estimated using the aptly suited linear regression model. To describe the generational effect on myopia prevalence over the next three decades, the prevalence of myopia in both children and adults, based on the available literature (1999 to 2020) was plotted against age, as the baseline. RESULTS: The prevalence of myopia in 5 to 15-year-old urban children increased from 4.44% in 1999 to 21.15% in 2019. Our predictions, based on the slope of 0.8% every year (4.05% for every 5 years) indicate that the prevalence of myopia will increase to 31.89% in 2030, 40.01% in 2040 and 48.14% in 2050. Due to the generational effect (caused by the nature of the condition lasting a lifetime once developed), there will be an overall increase in myopia prevalence across all age groups of 10.53% in the next three decades (2020 to 2050). CONCLUSION: The estimates of myopia prevalence across all age groups indicate the possible future epidemic of myopia in India within a few decades, similar to the situation in East Asian countries, unless active intervention to prevent myopia and changes in lifestyle are instigated to counteract myopia in India. Meticulously designed eye care services with focussed anti-myopia strategies are needed to control the rising myopia prevalence in India.

Do rectus muscle parameters vary between emmetropes and myopes?

PURPOSE: This study investigated the thickness, area, and insertion site of the medial (MR) and lateral (LR) rectus muscles in individuals with emmetropia and different degrees of myopia. METHODS: Swept-source optical coherence tomography images of the MR and LR muscles in 80 participants including emmetropes (spherical equivalent refractive error [SER] ±0.50 D, N = 14) and myopes (≤ -0.75 D, N = 66), were analysed. Custom-designed, semi-automated software was used to measure parameters such as insertion distance from limbus, muscle thickness at every 1 mm interval to 3 mm periphery and muscle area from insertion site to 3 mm. RESULTS: The median (Q1, Q3) SER error and axial length were -6.00 D (-13.25, -2.12) and 25.78 mm (23.78, 28.61), respectively. The MR was significantly thinner (mean ± SE: 137.7 ± 8.9 vs. 159.7 ± 8.9 µm, p < 0.01) and occupied less area than the LR (0.35 ± 0.01 vs. 0.42 ± 0.01 mm2 , respectively, p < 0.01). The thickness of the MR gradually increased from the insertion site to a 3 mm peripheral eccentric location (106.5 3.8 µm at 1 mm, 135.5 ± 4.5 µm at 2 mm and 156.1 ± 5.9 µm at 3 mm, p < 0.01). The overall median thickness of the MR was significantly less in myopes (129 µm [111.5, 152.2]) than emmetropes (158.1 [134.3, 167.7] µm, p = 0.03). However, no such trend was seen in the LR muscle. Muscle area and insertion distance were not different between emmetropes and myopes in both horizontal rectus muscles. CONCLUSION: Unlike the LR, the parameters of the MR (thin and occupying less area) show significant association with myopia. While the key finding of this study indicates the possible association of MR parameters with myopia, the clinical relevance of this finding and its role in myopiogenesis/progression needs to be investigated further.

Differences in retinal shape between East Asian and Caucasian eyes.

PURPOSE: To investigate whether retinal shape is different between East Asians and Caucasians. METHODS: There were 36 East Asian and 40 Caucasian young adults, with refractions between +0.75D and -5.50D. Peripheral eye lengths were obtained after pupil dilation using the Lenstar partial coherence interferometer. Measurements were obtained along the horizontal and vertical meridians of the visual field out to ±35° and ±30°, respectively, in 5° steps. Retinal co-ordinates were estimated using a validated method from the peripheral eye length measurements and ray-tracing through a modified Le Grand full theoretical eye. Rays were directed normally towards the anterior cornea. Retinal shapes were described in terms of vertex radius of curvature (Rv ), asphericity (Q) and equivalent radius of curvature (REq ) along both horizontal and vertical meridians. RESULTS: Rv was smaller in East Asian than in Caucasians (mean difference ± 95% CI -0.7 ± 0.5 mm), along the horizontal meridian than the vertical meridian (-1.2 ± 0.6 mm), and in myopia than in emmetropia (-1.0 ± 0.6 mm). Rv along the horizontal meridian, but not along the vertical meridian, became smaller as myopia increased. Q did not vary significantly with meridian, refraction group or race. The same pattern of results occurred for REq as for Rv . The percentage differences of heights under the estimated retinal surfaces showed steeper retinas in East Asians than in Caucasians; the differences between East Asian and Caucasian emmetropes were 2.5% and <1% along horizontal and vertical meridians, respectively, and corresponding differences for myopes were 4.6% and 1.8%. CONCLUSION: East Asians had steeper retinas than Caucasians. The horizontal meridian had steeper retinas than the vertical meridian. Myopes had steeper retinas than emmetropes. Racial differences in retinal shape in both emmetropes and myopes, combined with the high prevalence of myopia in East Asia, suggest that retinal shape may play a role in myopia development.

Peripheral Refraction, Peripheral Eye Length, and Retinal Shape in Myopia.

PURPOSE: To investigate how peripheral refraction and peripheral eye length are related to retinal shape. METHODS: Relative peripheral refraction (RPR) and relative peripheral eye length (RPEL) were determined in 36 young adults (M +0.75D to -5.25D) along horizontal and vertical visual field meridians out to ±35° and ±30°, respectively. Retinal shape was determined in terms of vertex radius of curvature Rv, asphericity Q, and equivalent radius of curvature REq using a partial coherence interferometry method involving peripheral eye lengths and model eye raytracing. Second-order polynomial fits were applied to RPR and RPEL as functions of visual field position. Linear regressions were determined for the fits' second order coefficients and for retinal shape estimates as functions of central spherical refraction. Linear regressions investigated relationships of RPR and RPEL with retinal shape estimates. RESULTS: Peripheral refraction, peripheral eye lengths, and retinal shapes were significantly affected by meridian and refraction. More positive (hyperopic) relative peripheral refraction, more negative RPELs, and steeper retinas were found along the horizontal than along the vertical meridian and in myopes than in emmetropes. RPR and RPEL, as represented by their second-order fit coefficients, correlated significantly with retinal shape represented by REq. CONCLUSIONS: Effects of meridian and refraction on RPR and RPEL patterns are consistent with effects on retinal shape. Patterns derived from one of these predict the others: more positive (hyperopic) RPR predicts more negative RPEL and steeper retinas, more negative RPEL predicts more positive relative peripheral refraction and steeper retinas, and steeper retinas derived from peripheral eye lengths predict more positive RPR.

Refractive indices used by the Haag-Streit Lenstar to calculate axial biometric dimensions.

PURPOSE: To estimate refractive indices used by the Lenstar biometer to translate measured optical path lengths into geometrical path lengths within the eye. METHODS: Axial lengths of model eyes were determined using the IOLMaster and Lenstar biometers; comparing those lengths gave an overall eye refractive index estimate for the Lenstar. Using the Lenstar Graphical User Interface, we noticed that boundaries between media could be manipulated and opposite changes in optical path lengths on either side of the boundary could be introduced. Those ratios were combined with the overall eye refractive index to estimate separate refractive indices. Furthermore, Haag-Streit provided us with a template to obtain 'air thicknesses' to compare with geometrical distances. RESULTS: The axial length estimates obtained using the IOLMaster and the Lenstar agreed to within 0.01 mm. Estimates of group refractive indices used in the Lenstar were 1.340, 1.341, 1.415, and 1.354 for cornea, aqueous, lens, and overall eye, respectively. Those refractive indices did not match those of schematic eyes, but were close in the cases of aqueous and lens. Linear equations relating air thicknesses to geometrical thicknesses were consistent with our findings. CONCLUSION: The Lenstar uses different refractive indices for different ocular media. Some of the refractive indices, such as that for the cornea, are not physiological; therefore, it is likely that the calibrations in the instrument correspond to instrument-specific corrections and are not the real optical path lengths.

Influence of eye rotation on peripheral eye length measurement obtained with a partial coherence interferometry instrument.

PURPOSE: The eye rotation approach for measuring peripheral eye length leads to concern about whether the rotation influences results, such as through pressure exerted by eyelids or extra-ocular muscles. This study investigated whether this approach is valid. METHODS: Peripheral eye lengths were measured with a Lenstar LS 900 biometer for eye rotation and no-eye rotation conditions (head rotation for horizontal meridian and instrument rotation for vertical meridian). Measurements were made for 23 healthy young adults along the horizontal visual field (± 30°) and, for a subset of eight participants along the vertical visual field (± 25°). To investigate the influence of the duration of eye rotation, for six participants measurements were made at 0, 60, 120, 180 and 210 s after eye rotation to ± 30° along horizontal and vertical visual fields. RESULTS: Peripheral eye lengths were not significantly different for the conditions along the vertical meridian (F1,7 = 0.16, p = 0.71). The peripheral eye lengths for the conditions were significantly different along the horizontal meridian (F1,22 = 4.85, p = 0.04), although not at individual positions (p ≥ 0.10) and were not important. There were no apparent differences between the emmetropic and myopic groups. There was no significant change in eye length at any position after maintaining position for 210 s. CONCLUSION: Eye rotation and no-eye rotation conditions were similar for measuring peripheral eye lengths along horizontal and vertical visual field meridians at ± 30° and ± 25°, respectively. Either condition can be used to estimate retinal shape from peripheral eye lengths.

Randomised clinical trial of extended depth of focus lenses for controlling myopia progression: Outcomes from SEED LVPEI Indian Myopia Study.

PURPOSE: To determine the efficacy of extended depth of focus (EDOF) contact lenses for controlling myopia progression in children through a 1-year randomised clinical trial. METHODS: A total of 104 children aged 7-15 years, with spherical equivalent refraction ≤-0.50 D, were randomly assigned to wear SEED 1 dayPure EDOF Mid contact lenses (n=48) or single vision spectacle lenses (n=56). Cycloplegic refraction with Shin-Nippon open field autorefractor and axial length with Lenstar LS 900 was determined at the baseline and 12-month visits. The compliance, visual discomfort and dryness questionnaires were administered during the final visit. RESULTS: Sixty-nine children (control: n=38; treatment: 31) completed the 12-month follow-up visit, with no difference in baseline characteristics between the groups. Mean (SEM) myopia progression in the 12th month was -0.48±0.07D in the control group and -0.20±0.08D in the treatment group. Mean axial elongation was 0.22±0.03 mm and 0.11±0.03 mm in the control and treatment groups, respectively. SEED 1 dayPure EDOF Mid contact lenses slowed myopia progression by 59% (-0.28D; p=0.01) based on spherical equivalent refraction and controlled axial length by 49% (0.11 mm; p=0.007) in comparison to single vision spectacle lenses. None of the participants reported any adverse effects. While most of the participants (82%) were comfortable with the contact lenses, 11% reported occasional dryness and 14% experienced mild fluctuations in visual acuity after immediate lens wear. CONCLUSION: Daily wear of SEED 1 dayPure EDOF Mid contact lenses in Indian children showed a significant effect in controlling myopia progression and axial elongation.