yes / In this study, we investigated whether reading influences contrast adaptation differently in young adult emmetropic and myopic participants at the spatial frequencies created by text rows and character strokes. Pre-adaptation contrast sensitivity was measured for test gratings with spatial frequencies of 1cdeg-1 and 4cdeg-1, presented horizontally and vertically. Participants then adapted to reading text corresponding to the horizontal “row frequency” of text (1cdeg-1), and vertical “stroke frequency” of the characters (4cdeg-1) for 180s. Following this, post-adaptation contrast sensitivity was measured. Twenty young adults (10 myopes, 10 emmetropes) optimally corrected for the viewing distance participated. There was a significant reduction in logCS post-text adaptation (relative to pre-adaptation logCS) at the row frequency (1cdeg-1 horizontal) but not at the stroke frequency (4cdeg-1 vertical). logCS changes due to adaptation at 1cdeg-1 horizontal were significant in both emmetropes and myopes. Comparing the two refractive groups, myopic participants showed significantly greater adaptation compared to emmetropic participants. Reading text on a screen induces contrast adaptation in young adult observers. Myopic participants were found to exhibit greater contrast adaptation than emmetropes at the spatial frequency corresponding to the text row frequency. No contrast adaptation was observed at the text stroke frequency in either participant group. The greater contrast adaptation experienced by myopes after reading warrants further investigation to better understand the relationship between near work and myopia development.

Yes / PURPOSE. To test the hypothesis that emmetropization buffers against genetic and environmental risk factors for myopia by investigating whether risk factor effect sizes vary depending on children’s position in the refractive error distribution. METHODS. Refractive error was assessed in participants from two birth cohorts: Avon Longitudinal Study of Parents and Children (ALSPAC) (noncycloplegic autorefraction) and Generation R (cycloplegic autorefraction). A genetic risk score for myopia was calculated from genotypes at 146 loci. Time spent reading, time outdoors, and parental myopia were ascertained from parent-completed questionnaires. Risk factors were coded as binary variables (0 = low, 1 = high risk). Associations between refractive error and each risk factor were estimated using either ordinary least squares (OLS) regression or quantile regression. RESULTS. Quantile regression: effects associated with all risk factors (genetic risk, parental myopia, high time spent reading, low time outdoors) were larger for children in the extremes of the refractive error distribution than for emmetropes and low ametropes in the center of the distribution. For example, the effect associated with having a myopic parent for children in quantile 0.05 vs. 0.50 was as follows: ALSPAC: age 15, –1.19 D (95% CI –1.75 to –0.63) vs. –0.13 D (–0.19 to –0.06), P = 0.001; Generation R: age 9, –1.31 D (–1.80 to –0.82) vs. –0.19 D (–0.26 to –0.11), P < 0.001. Effect sizes for OLS regression were intermediate to those for quantiles 0.05 and 0.50. CONCLUSIONS. Risk factors for myopia were associated with much larger effects in children in the extremes of the refractive error distribution, providing indirect evidence that emmetropization buffers against both genetic and environmental risk factors. / UK Medical Research Council and Wellcome (grant ref: 102215/2/13/2), and the University of Bristol provided core support for ALSPAC. This research was specifically funded by the UK National Eye Research Centre (grant SAC015), the Global Education Program of the Russian Federation government, a PhD studentship grant from the UK College of Optometrists (“Genetic Prediction of Individuals At-Risk for Myopia Development”), and an NIHR Senior Research Fellowship award SRF-2015-08-005. The Generation R study is supported by the Erasmus Medical Center, Rotterdam, Erasmus University, Rotterdam, the Netherlands; the Netherlands Organization of Scientific Research (NWO); Netherlands Organization for the Health Research and Development (ZonMw); the Ministry of Education, Culture and Science; the Ministry for Health,Welfare and Sports; the European Commission (DG XII); European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Programme (grant 648268); the Netherlands Organization for Scientific Research (NWO, grant 91815655); and Oogfonds, ODAS, Uitzicht 2017-28 (LSBS, MaculaFonds, Oogfonds).

Yes / Cross-sectional and longitudinal studies have consistently reported an association between education and myopia. However, conventional observational studies are at risk of bias due to confounding by factors such as socioeconomic position and parental educational attainment. The current study aimed to estimate the causal effect of education on refractive error using regression discontinuity analysis. Methods: Regression discontinuity analysis was applied to assess the influence on refractive error of the raising of the school leaving age (ROSLA) from 15 to 16 years introduced in England and Wales in 1972. For comparison, a conventional ordinary least squares (OLS) analysis was performed. The analysis sample comprised 21,548 UK Biobank participants born in a nine-year interval centered on September 1957, the date of birth of those first affected by ROSLA. Results: In OLS analysis, the ROSLA 1972 reform was associated with a −0.29 D (95% confidence interval [CI]: −0.36 to −0.21, P < 0.001) more negative refractive error. In other words, the refractive error of the study sample became more negative by −0.29 D during the transition from a minimum school leaving age of 15 to 16 years of age. Regression discontinuity analysis estimated the causal effect of the ROSLA 1972 reform on refractive error as −0.77 D (95% CI: −1.53 to −0.02, P = 0.04). Conclusions: Additional compulsory schooling due to the ROSLA 1972 reform was associated with a more negative refractive error, providing additional support for a causal relationship between education and myopia. / Global Education program of the Russian Federation government (DP) and an NIHR Senior Research Fellowship award SRF-2015-08-005 (CW), The Department for Health through an award made by the NIHR to the Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust, and UCL Institute of Ophthalmology, London, United Kingdom (grant no. BRC2_009). Additional support was provided by The Special Trustees of Moorfields Eye Hospital, London, United Kingdom (grant no. ST 12 09)

Yes / Background: Myopia has been shown to have a complex mode of inheritance, being influenced by both genetic and environmental factors. Here, an introduction into myopia genetics is given, with the shortcomings of current genetic prediction for myopia discussed, including the proportionally limited research on genetic prediction in people of non-European ancestry. A previously developed genetic risk score derived from European participants was evaluated in participants of non-European ancestry. Methods: Participants from UK Biobank who self-reported their ethnicity as “Asian”, “Chinese”, or “Black” and who had refractive error and genetic data available were included in the analysis. Ancestral homogeneity was confirmed using principal component analysis, resulting in samples of 3500 Asian, 444 Chinese, and 3132 Black participants. A published refractive error GWAS meta-analysis of 711,984 participants of European ancestry was used to create a weighted genetic risk score model which was then applied to participants from each ethnic group. Accuracy of genetic prediction of refractive error was estimated as the proportion of variance explained (PVE). Receiver operating characteristic (ROC) curves were developed to estimate myopia prediction performance at three thresholds: any myopia (equal to or more than 0.75D), moderate myopia (between -3.00D and -4.99D) and high myopia (equal to or more than -5.00D). Odds ratios for myopia were calculated for the participants in the top 10th or 5th percentile of genetic risk score distribution, comparing them to the remainder of the population. Results: The PVE value for refractive error was 6.4%, 6.2%, and 1.5% for those with Asian, Chinese and Black ethnicity, respectively (compared to 11.2% in Europeans). Odds ratios for any myopia and moderate myopia development for those within the top 10th and 5th percentile of genetic risk were significant in all ethnic groups P<0.05). However, the genetic risk score was not able to reliably identify those at risk of high myopia, other than for participants of Chinese ethnicity (P<0.05). Conclusion: Prediction of refractive error in Asian, Chinese and Black participants was ~57%, 55% and 13% as accurate in comparison to prediction in European participants. Further research in diverse ethnic populations is needed to improve prediction accuracy. / This research has been conducted using the UK Biobank Resource (applications #17351). UK Biobank was established by the Wellcome Trust; the UK Medical Research Council; the Department for Health (London, UK); Scottish Government (Edinburgh, UK); and the Northwest Regional Development Agency (Warrington, UK). It also received funding from the Welsh Assembly Government (Cardiff, UK); the British Heart Foundation; and Diabetes UK. Collection of eye and vision data was supported by The Department for Health through an award made by the NIHR to the Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust, and UCL Institute of Ophthalmology, London, United Kingdom (grant no. BRC2_009). Additional support was provided by The Special Trustees of Moorfields Eye Hospital, London, United Kingdom (grant no. ST 12 09). Many parts of this project were performed during the time that author Neema Ghorbani Mojarrad was supported by the College of Optometrists with a Postgraduate Scholarship.

This thesis has investigated nearwork-induced transient myopia and accommodation responses in relation to refractive stability, multichromatic stimuli and orthokeratology. Five individual studies have been carried out. Initially an investigation into the temporal and dioptric aspects of nearwork-induced transient myopia was undertaken, suggesting that increased task duration does not increase the level, or slow the regression of post-task NITM, however an increase in the dioptric demand of the task does. In the second study, a longitudinal myopia progression study, these findings were related to short term myopia progression. The third investigation demonstrates the feasibility of measuring the biometric correlates of nearwork-induced transient myopia using a low coherence reflectometry device (LenStar, Haag Streit Koeniz, Switzerland). Fourthly, a comparison of the differences between static and dynamic accommodative responses, microfluctuations and nearwork-induced transient myopia produced when viewing a black/white target as oppose to a red/blue target has suggested the possibility of four accommodative responses to this multichromatic stimulus. Further investigation will be necessary to investigate if any of these response types are related to myopia progression. 2 The final study investigates the effect of two different designs of orthokeratology contact lenses (C5 and polynomial) on visual function. It appears to be the case that although the polynomial lens design has a larger refractive effect than the C5 lens it reduces both high and low contrast corrected visual acuity to a greater extent. The higher the baseline mean spherical equivalent refractive error the larger the detrimental effect. / College of Optometrists

The increasing prevalence of myopia over the past few decades and its association with potential ocular complications make myopia an important research topic. The present work is concerned with the structural and functional characteristics of a group of myopic and emmetropic individuals. The technical experiments in this work investigated firstly the effect of instrument alignment on peripheral refraction measurements and revealed that the corneal vertex was an acceptable alignment position of the Shin-Nippon NVision-K 5001 autorefractor, allowing consistent alignment with other instruments used in this research. Secondly, spectacles could be used to provide comparable vision to contact lenses in the visual performance studies. In the main experimental parts of this work, visual performance and multiple aspects of ocular structure were assessed across a wide range of eccentricities along the horizontal and vertical meridians within the same eyes. The structural properties of the myopic eye were measured through central and peripheral autorefraction, and through cornea to retina dimensions using non-contact biometry. In addition, the central and peripheral resolution acuities of myopic and emmetropic eyes for high and low contrast levels were investigated. Our structural and functional measurements revealed relatively prolate myopic eyes with reduced high contrast resolution acuity, compared to emmetropic eyes. Moreover, multiple regression analyses were performed at the fovea and outermost retinal eccentricities common to all core experiments but revealed no strong relationship between the structure and function of the myopic eye. Finally, regarding asymmetry, the nasal and superior retinae were found to be longer and to perform better in comparison to the temporal and superior retinae respectively.

The relationship between accommodation and myopia has been under investigation for many years, and the effort to understand it is ongoing. In this thesis, an introduction to the state of myopia research is given first, with particular reference to studies of accommodation and higher-order ocular aberrations, which feature in the subsequent chapters. Following a brief introduction to the general technique of aberrometry and visual stimulus control using adaptive optics, the development of a monocular adaptive optics instrument for this purpose is described. The instrument is used to vary a dioptric stimulus and record the accommodation response in pilot studies and a detailed experiment, which has also been published elsewhere. It is found, among other things, that accommodation can respond to more than one different input level during its latency period, and that such inputs can be stored until components of the accommodation control system are free to process them. Indications of a minimum halting time for accommodation, of around 0.6 s, are presented. In later chapters, the development and testing of a new, binocular adaptive optics apparatus will be found. As well as binocular aberrometry and adaptive optics control of stimulus aberrations, this instrument displaces images to allow for and stimulate ocular convergence in binocular accommodation experiments. It is the first instrument in the world with its combined functionalities. Finally, the contribution of this thesis is summarised, and further instrumentation development and experiments are put forward for the continuation of this branch of accommodation and myopia research.

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