The Role of Educational Attainment in Refraction: The Genes in Myopia (GEM) Twin Study

PURPOSE. Educational attainment has been proposed as one of the most consistent environmental risk factors associated with myopia. The Genes in Myopia (GEM) twin study is the first myopia twin study to determine the relative genetic contribution in educational attainment as well as assessing the shared genetic and environmental factors between educational attainment and refraction through structural equation modeling. METHODS. All twins from Victoria aged 18 years or older were invited to participate in this study through the Australian Twin Registry (ATR). Each twin completed a general questionnaire, and a comprehensive eye examination was undertaken. Education level was categorized to provide a level of attainment. RESULTS. A total of 612 twin pairs with a mean age of 52.36 years were examined. Higher educational attainment was significantly associated with a more myopic refraction (r ϭ Ϫ0.21, P Ͻ 0.01), with educational attainment explaining 4.41% of the total variance in refraction. Findings from the GEM twin study found that genes (additive genetic effects) explained 69% of the variance in educational attainment and common and unique environmental factors accounted for 20% and 11% of the variance, respectively. Of the genetic influences on refraction, 3.2% were common with those influencing educational attainment. CONCLUSIONS. The GEM twin study has shown that educational attainment is strongly influenced by genes, and therefore this risk factor should not solely be considered as an environmental risk factor. The same genetic factors that influence an individual's educational attainment may also be involved in the development of refractive error. (Invest Ophthalmol Vis Sci. 2008; 49:534 -538) DOI:10.1167/iovs.07-1123 A pproximately 20% to 25% of individuals in Western populations have myopia or near-sightedness, 1,2 with the prevalence being much higher (80%) in urbanized areas of Asia. 6 Major evidence to support a genetic contribution to myopia has come from twin studies and family-based linkage studies. Several twin studies 7-10 have collectively provided evidence to support a major genetic component, with concordance for myopia between identical (monozygotic) twins (r Ͼ 0.80) approximately twice that for myopia in nonidentical (dizygotic) twins (r Ͻ 0.4). As such, heritability estimates from twin studies range from 60% to 90% for refraction 8 More recently, family-based linkage studies have identified at least 14 myopia loci (MYP1 to -14) associated with all forms of myopia. 12 So far, no gene(s) have been significantly associated with myopia in these regions. Several environmental risk factors have been implicated as playing a role in myopia including intelligence and, most frequently, near-work activity. 14 -16 For instance, a recent study by Saw et al. 16 Nonetheless, considering myopia is complex in nature, it is essential to understand whether such risk factors are purely environmental or whether they share a common genetic basis with myopia. First, the etiology of these risk factors must be elucidated. For instance, what combination of social, cultural, environmental or genetic influences constitutes an individual's educational attainment? Considering the difficulty of obtaining accurate measures of near-work activity retrospectively, it is common for studies to use educational attainment as a surrogate measure for near work in studies of myopia. 17 Studies into educational attainment have reported heritability estimates reaching as high as 60%. 10 The use of twin studies is an effective tool in exploring gene-environment interactions (the magnitude of the effect of a genetic variant caused by a change in the environment) by quantifying the genetic component in disease while accounting for environmental factors in the same individuals. Jinks and Fulker 22 introduced a test to detect gene-environment interactions in disease through the analysis of MZ twin pairs. A gene-environment interaction is indicated when absolute differences (MZ twin 1 Ϫ MZ twin 2 ϭ environment effects) for any measure of interest in MZ twin pairs are significantly associated with the corresponding sums (MZ twin 1 ϩ MZ twin From th

Association between digital smart device use and myopia: a systematic review and meta-analysis

Background- Excessive use of digital smart devices, including smartphones and tablet computers, could be a risk factor for myopia. We aimed to review the literature on the association between digital smart device use and myopia. Methods- In this systematic review and meta-analysis we searched MEDLINE and Embase, and manually searched reference lists for primary research articles investigating smart device (ie, smartphones and tablets) exposure and myopia in children and young adults (aged 3 months to 33 years) from database inception to June 2 (MEDLINE) and June 3 (Embase), 2020. We included studies that investigated myopia-related outcomes of prevalent or incident myopia, myopia progression rate, axial length, or spherical equivalent. Studies were excluded if they were reviews or case reports, did not investigate myopia-related outcomes, or did not investigate risk factors for myopia. Bias was assessed with the Joanna Briggs Institute Critical Appraisal Checklists for analytical cross-sectional and cohort studies. We categorised studies as follows: category one studies investigated smart device use independently; category two studies investigated smart device use in combination with computer use; and category three studies investigated smart device use with other near-vision tasks that were not screen-based. We extracted unadjusted and adjusted odds ratios (ORs), β coefficients, prevalence ratios, Spearman's correlation coefficients, and p values for associations between screen time and incident or prevalent myopia. We did a meta-analysis of the association between screen time and prevalent or incident myopia for category one articles alone and for category one and two articles combined. Random-effects models were used when study heterogeneity was high (I2>50%) and fixed-effects models were used when heterogeneity was low (I2≤50%). Findings- 3325 articles were identified, of which 33 were included in the systematic review and 11 were included in the meta-analysis. Four (40%) of ten category one articles, eight (80%) of ten category two articles, and all 13 category three articles used objective measures to identify myopia (refraction), whereas the remaining studies used questionnaires to identify myopia. Screen exposure was measured by use of questionnaires in all studies, with one also measuring device-recorded network data consumption. Associations between screen exposure and prevalent or incident myopia, an increased myopic spherical equivalent, and longer axial length were reported in five (50%) category one and six (60%) category two articles. Smart device screen time alone (OR 1·26 [95% CI 1·00–1·60]; I2=77%) or in combination with computer use (1·77 [1·28–2·45]; I2=87%) was significantly associated with myopia. The most common sources of risk of bias were that all 33 studies did not include reliable measures of screen time, seven (21%) did not objectively measure myopia, and nine (27%) did not identify or adjust for confounders in the analysis. The high heterogeneity between studies included in the meta-analysis resulted from variability in sample size (range 155–19 934 participants), the mean age of participants (3–16 years), the standard error of the estimated odds of prevalent or incident myopia (0·02–2·21), and the use of continuous (six [55%] of 11) versus categorical (five [46%]) screen time variables Interpretation- Smart device exposure might be associated with an increased risk of myopia. Research with objective measures of screen time and myopia-related outcomes that investigates smart device exposure as an independent risk factor is required

Non-invasive in vivo hyperspectral imaging of the retina for potential biomarker use in Alzheimer's disease

Studies of rodent models of Alzheimer's disease (AD) and of human tissues suggest that the retinal changes that occur in AD, including the accumulation of amyloid beta (Abeta), may serve as surrogate markers of brain Abeta levels. As Abeta has a wavelength-dependent effect on light scatter, we investigate the potential for in vivo retinal hyperspectral imaging to serve as a biomarker of brain Abeta. Significant differences in the retinal reflectance spectra are found between individuals with high Abeta burden on brain PET imaging and mild cognitive impairment (n = 15), and age-matched PET-negative controls (n = 20). Retinal imaging scores are correlated with brain Abeta loads. The findings are validated in an independent cohort, using a second hyperspectral camera. A similar spectral difference is found between control and 5xFAD transgenic mice that accumulate Abeta in the brain and retina. These findings indicate that retinal hyperspectral imaging may predict brain Abeta load

The state of HRM in the Middle East:Challenges and future research agenda

Based on a robust structured literature analysis, this paper highlights the key developments in the field of human resource management (HRM) in the Middle East. Utilizing the institutional perspective, the analysis contributes to the literature on HRM in the Middle East by focusing on four key themes. First, it highlights the topical need to analyze the context-specific nature of HRM in the region. Second, via the adoption of a systematic review, it highlights state of development in HRM in the research analysis set-up. Third, the analysis also helps to reveal the challenges facing the HRM function in the Middle East. Fourth, it presents an agenda for future research in the form of research directions. While doing the above, it revisits the notions of “universalistic” and “best practice” HRM (convergence) versus “best-fit” or context distinctive (divergence) and also alternate models/diffusion of HRM (crossvergence) in the Middle Eastern context. The analysis, based on the framework of cross-national HRM comparisons, helps to make both theoretical and practical implications

Ten golden rules for optimal antibiotic use in hospital settings: the WARNING call to action

Antibiotics are recognized widely for their benefits when used appropriately. However, they are often used inappropriately despite the importance of responsible use within good clinical practice. Effective antibiotic treatment is an essential component of universal healthcare, and it is a global responsibility to ensure appropriate use. Currently, pharmaceutical companies have little incentive to develop new antibiotics due to scientific, regulatory, and financial barriers, further emphasizing the importance of appropriate antibiotic use. To address this issue, the Global Alliance for Infections in Surgery established an international multidisciplinary task force of 295 experts from 115 countries with different backgrounds. The task force developed a position statement called WARNING (Worldwide Antimicrobial Resistance National/International Network Group) aimed at raising awareness of antimicrobial resistance and improving antibiotic prescribing practices worldwide. The statement outlined is 10 axioms, or “golden rules,” for the appropriate use of antibiotics that all healthcare workers should consistently adhere in clinical practice

Body stature and myopia: the genes in myopia (GEM) twin study

Objective: A consensus regarding whether a “myopia body stature” exists is still unclear with previous literature being inconsistent and conflicting. We wished to explore the relationship of body stature and myopia using a large Australian twin cohort [The Genes in Myopia (GEM) twin study]. Methods: All twins examined in the GEM twin study were recruited from the Australian Twin Registry (ATR). Each twin underwent a standard questionnaire, comprehensive eye examination and anthropometric (height and weight) measures were obtained. Myopia was defined as spherical equivalent, equal to or worse than -0.50 Diopters (D) Results: A total of 1224 twins (690 monozygotic twins and 534 dizygotic twins) aged between 18 to 86 years (mean age = 52.36 years) were recruited into the GEM study. The mean height [meters (m)] and weight [kilograms (kg)] of all twins in the GEM study was 1.67 m (1.44 m to 1.95 m) and 71.66 kg (40 kg to 167 kg), respectively. In the heaviest individuals (greater than or equal to 80kg), there was a significant risk (OR 1.48, p = 0.01) of having myopia compared to those in the lightest quartile of weight (less than 61 kg). However, when gender was analyzed separately, this significant risk remained only for females (OR:1.79, p = 0.01). Conclusion: Females in the heaviest quartile of weight have a significantly increased risk of myopia compared to those in the lightest weight quartile in our twin study population. Our study adds to the growing consensus that anthropometric measures should be considered as potential risk factors in myopia

The Role of Educational Attainment in Refraction: The Genes in Myopia (GEM) Twin Study

PURPOSE. Educational attainment has been proposed as one of the most consistent environmental risk factors associated with myopia. The Genes in Myopia (GEM) twin study is the first myopia twin study to determine the relative genetic contribution in educational attainment as well as assessing the shared genetic and environmental factors between educational attainment and refraction through structural equation modeling. METHODS. All twins from Victoria aged 18 years or older were invited to participate in this study through the Australian Twin Registry (ATR). Each twin completed a general questionnaire, and a comprehensive eye examination was undertaken. Education level was categorized to provide a level of attainment. RESULTS. A total of 612 twin pairs with a mean age of 52.36 years were examined. Higher educational attainment was significantly associated with a more myopic refraction (r ϭ Ϫ0.21, P Ͻ 0.01), with educational attainment explaining 4.41% of the total variance in refraction. Findings from the GEM twin study found that genes (additive genetic effects) explained 69% of the variance in educational attainment and common and unique environmental factors accounted for 20% and 11% of the variance, respectively. Of the genetic influences on refraction, 3.2% were common with those influencing educational attainment. CONCLUSIONS. The GEM twin study has shown that educational attainment is strongly influenced by genes, and therefore this risk factor should not solely be considered as an environmental risk factor. The same genetic factors that influence an individual's educational attainment may also be involved in the development of refractive error. (Invest Ophthalmol Vis Sci. 2008; 49:534 -538) DOI:10.1167/iovs.07-1123 A pproximately 20% to 25% of individuals in Western populations have myopia or near-sightedness, 1,2 with the prevalence being much higher (80%) in urbanized areas of Asia. 6 Major evidence to support a genetic contribution to myopia has come from twin studies and family-based linkage studies. Several twin studies 7-10 have collectively provided evidence to support a major genetic component, with concordance for myopia between identical (monozygotic) twins (r Ͼ 0.80) approximately twice that for myopia in nonidentical (dizygotic) twins (r Ͻ 0.4). As such, heritability estimates from twin studies range from 60% to 90% for refraction 8 More recently, family-based linkage studies have identified at least 14 myopia loci (MYP1 to -14) associated with all forms of myopia. 12 So far, no gene(s) have been significantly associated with myopia in these regions. Several environmental risk factors have been implicated as playing a role in myopia including intelligence and, most frequently, near-work activity. 14 -16 For instance, a recent study by Saw et al. 16 Nonetheless, considering myopia is complex in nature, it is essential to understand whether such risk factors are purely environmental or whether they share a common genetic basis with myopia. First, the etiology of these risk factors must be elucidated. For instance, what combination of social, cultural, environmental or genetic influences constitutes an individual's educational attainment? Considering the difficulty of obtaining accurate measures of near-work activity retrospectively, it is common for studies to use educational attainment as a surrogate measure for near work in studies of myopia. 17 Studies into educational attainment have reported heritability estimates reaching as high as 60%. 10 The use of twin studies is an effective tool in exploring gene-environment interactions (the magnitude of the effect of a genetic variant caused by a change in the environment) by quantifying the genetic component in disease while accounting for environmental factors in the same individuals. Jinks and Fulker 22 introduced a test to detect gene-environment interactions in disease through the analysis of MZ twin pairs. A gene-environment interaction is indicated when absolute differences (MZ twin 1 Ϫ MZ twin 2 ϭ environment effects) for any measure of interest in MZ twin pairs are significantly associated with the corresponding sums (MZ twin 1 ϩ MZ twin From th

Screening for sight-threatening diabetic retinopathy: An update

Aims: To review the literature on Screening for Diabetic Retinopathy. Materials and Methods: A comprehensive review of the English language literature, published from March 1980 to June 2014 using key words in Zetoc. Results: Several methods were found to achieve adequate sensitivities and specificities for diabetic retinopathy screening. Studies were compared with respect to (a) Classifications used to grade diabetic retinopathy (b) The evidence for population-based screening for diabetic retinopathy (c) Alternatives to digital photography for screening (d) Reference standards used to study the effectiveness of screening methods (e) The evidence for mydriatic versus non-mydriatic digital photography, or a combination of the two (f) The number of photographic fields captured (g) Measurement of distance visual acuity (h)  Cost-effectiveness of screening for diabetic retinopathy (i) Future developments in screening for diabetic retinopathy Conclusion: Based on an assessment of available studies, the most effective DR screening strategy is the use of mydriatic or staged mydriasis with digital retinal photography. Variables between different screening strategies include whether Visual Acuity is measured and the number of fields captured