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Hiyoshi A, Hawkes CH, Neffendorf JE, Olsson T, Giovannoni G, Montgomery S. Myopia in late adolescence and subsequent multiple sclerosis among men. Mult Scler Relat Disord 2023; 71:104577. [PMID: 36863085 DOI: 10.1016/j.msard.2023.104577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Revised: 01/27/2023] [Accepted: 02/12/2023] [Indexed: 02/17/2023]
Abstract
BACKGROUND Risk factors such as low vitamin D level has been implicated in the etiology of multiple sclerosis (MS) and may be relevant to myopia, such that there may be an association between myopia and MS. METHODS Using linked Swedish national register data, we conducted a cohort study of men who were born in Sweden between 1950 and 1992, lived in Sweden between 1990 and 2018, and enrolled in military conscription assessment (n = 1,847,754). Myopia was defined based on the spherical equivalent refraction measured at conscription assessment, around age 18 years. Multiple sclerosis was identified using the Patient Register. Cox regression produced hazard ratios (HR) with 95% confidence intervals (95% CI), with adjustment for demographic and childhood socioeconomic characteristics and residential region. Due to changes in the assessment of refractive error, the analysis was stratified into two groups by the year of conscription assessment: 1969-1997 and 1997-2010. RESULTS Among 1,559,859 individuals during a maximum of 48 years of follow-up from age 20 to 68 years (44,715,603 person-years), there were 3,134 MS events, and the incidence rate 7.0 (95% CI [6.8, 7.3] per 100,000 person-years). Among individuals with conscription assessments during 1997-2010, there were 380 MS events. There was no evidence of an association between myopia and MS, with HR 1.09 (95% CI 0.83, 1.43). Among individuals who underwent conscription assessment in 1969-1997, there were 2754 MS events. After adjusting for all covariates, there was no evidence of an association between myopia and MS (HR 0.99 [95% CI 0.91, 1.09]). CONCLUSION Myopia in late adolescence is not associated with a subsequent raised risk of MS and thus there does not appear to be important shared risk factors.
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Affiliation(s)
- Ayako Hiyoshi
- Clinical Epidemiology and Biostatistics, Faculty of Medicine and Health, School of Medical Sciences, Örebro University, Campus USÖ, Södra Grev Rosengatan 30, Örebro 703 62, Sweden; Department of Public Health Sciences, Stockholm University, Stockholm SE-106 91, Sweden; Department of Epidemiology and Public Health, University College London, 1-19 Torrington Place, London WC1E 7HB, United Kingdom
| | | | - James E Neffendorf
- Department of Ophthalmology, King's College Hospital, London SE5 9RS, UK
| | - Tomas Olsson
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm 171 77, Sweden
| | - Gavin Giovannoni
- Neuroimmunology Unit, Blizard Institute, Queen Mary, University of London, UK
| | - Scott Montgomery
- Clinical Epidemiology and Biostatistics, Faculty of Medicine and Health, School of Medical Sciences, Örebro University, Campus USÖ, Södra Grev Rosengatan 30, Örebro 703 62, Sweden; Department of Epidemiology and Public Health, University College London, 1-19 Torrington Place, London WC1E 7HB, United Kingdom; Clinical Epidemiology Division, Department of Medicine, Solna, Karolinska Institutet, Stockholm 171 77, Sweden.
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Myopia Genetics and Heredity. CHILDREN 2022; 9:children9030382. [PMID: 35327754 PMCID: PMC8947159 DOI: 10.3390/children9030382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 02/19/2022] [Accepted: 03/03/2022] [Indexed: 11/18/2022]
Abstract
Myopia is the most common eye condition leading to visual impairment and is greatly influenced by genetics. Over the last two decades, more than 400 associated gene loci have been mapped for myopia and refractive errors via family linkage analyses, candidate gene studies, genome-wide association studies (GWAS), and next-generation sequencing (NGS). Lifestyle factors, such as excessive near work and short outdoor time, are the primary external factors affecting myopia onset and progression. Notably, besides becoming a global health issue, myopia is more prevalent and severe among East Asians than among Caucasians, especially individuals of Chinese, Japanese, and Korean ancestry. Myopia, especially high myopia, can be serious in consequences. The etiology of high myopia is complex. Prediction for progression of myopia to high myopia can help with prevention and early interventions. Prediction models are thus warranted for risk stratification. There have been vigorous investigations on molecular genetics and lifestyle factors to establish polygenic risk estimations for myopia. However, genes causing myopia have to be identified in order to shed light on pathogenesis and pathway mechanisms. This report aims to examine current evidence regarding (1) the genetic architecture of myopia; (2) currently associated myopia loci identified from the OMIM database, genetic association studies, and NGS studies; (3) gene-environment interactions; and (4) the prediction of myopia via polygenic risk scores (PRSs). The report also discusses various perspectives on myopia genetics and heredity.
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Saw SM. A synopsis of the prevalence rates and environmental risk factors for myopia. Clin Exp Optom 2021; 86:289-94. [PMID: 14558850 DOI: 10.1111/j.1444-0938.2003.tb03124.x] [Citation(s) in RCA: 125] [Impact Index Per Article: 41.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2002] [Revised: 01/10/2003] [Accepted: 02/03/2003] [Indexed: 11/28/2022] Open
Abstract
The prevalence rates of myopia are higher in urban Asian cities such as Hong Kong and Singapore. One observation over the past few decades is that the prevalence rates of myopia have been rising and there is an epidemic of myopia in Asia. The age-old question of the roles of nature and nurture in this process remains unanswered. The strongest evidence for an environmental link to myopia is near work activity. Childhood exposure to night lighting has also been explored in different studies but the results have been mixed. Twin studies, segregation analysis and association studies have demonstrated that hereditary factors play an important role in myopia development. The exact nature and interplay of genetic and environmental factors is not known and data suggest that environmental factors may interact with genetic factors to increase the risks of developing myopia. Future research is needed to identify specific modifiable lifestyle factors and genetic markers for myopia. This will enable preventive measures such as health education to be instituted.
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Affiliation(s)
- Seang-Mei Saw
- Department of Community Occupational and Family Medicine, National University of Singapore, 16 Medical Drive, Singapore, 117597, Republic of Singapore
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4
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Pusti D, Benito A, Madrid-Valero JJ, Ordoñana JR, Artal P. Inheritance of Refractive Error in Millennials. Sci Rep 2020; 10:8173. [PMID: 32424231 PMCID: PMC7235039 DOI: 10.1038/s41598-020-65130-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 04/22/2020] [Indexed: 12/13/2022] Open
Abstract
Over the last decades, the prevalence of myopia has suddenly increased, and at this rate, half of the world's population will be myopic by the year 2050. Contemporary behavioural and lifestyle circumstances, along with emergent technology, are thought to be responsible for this increase. Twin studies mostly reported a high heritability of refractive error across ethnicities. However, heritability is a population statistic and could vary as a result of changing environmental conditions. We studied the variance of refractive error in millennials with 100 twin pairs of university students in southeast Spain. The study population presented a high prevalence of myopia (77%). Statistical analysis showed the variance of refractive error in this group of young twins was mainly driven by the shared environment and, to a lesser extent, by additive genetic factors. We found an increase in myopia prevalence accompanied by a decrease in heritability in this sample of millennials in contrast with results from a previous generation group from the same ethnic origin.
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Affiliation(s)
- Dibyendu Pusti
- Laboratorio de Óptica, Instituto Universitario de Investigación en Óptica y Nanofísica, Universidad de Murcia, Campus de Espinardo (Ed. 34), 30100, Murcia, Spain.
| | - Antonio Benito
- Laboratorio de Óptica, Instituto Universitario de Investigación en Óptica y Nanofísica, Universidad de Murcia, Campus de Espinardo (Ed. 34), 30100, Murcia, Spain
| | - Juan J Madrid-Valero
- Registro de Gemelos de Murcia, Departamento de Anatomía Humana y Psicobiología, Universidad de Murcia, Murcia, Spain
- Instituto Murciano de Investigación Biosanitaria (IMIB-Arrixaca), Universidad de Murcia, Murcia, Spain
| | - Juan R Ordoñana
- Registro de Gemelos de Murcia, Departamento de Anatomía Humana y Psicobiología, Universidad de Murcia, Murcia, Spain
- Instituto Murciano de Investigación Biosanitaria (IMIB-Arrixaca), Universidad de Murcia, Murcia, Spain
| | - Pablo Artal
- Laboratorio de Óptica, Instituto Universitario de Investigación en Óptica y Nanofísica, Universidad de Murcia, Campus de Espinardo (Ed. 34), 30100, Murcia, Spain
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5
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Abstract
Myopia is one of the most prevalent eye diseases, and its advanced form, high myopia, is a leading cause of subsequent pathologic myopia, which in turn results in an increased risk of retinal diseases. The prevalence of myopia and high myopia is 28.3% and 4.0% of the global population, respectively, and these numbers are estimated to increase to 49.8% for myopia 9.8% for high myopia by 2050, thus making myopia a severe global socioeconomic problem. The eye shape has been receiving increasing attention as a possible biomarker for myopia. Among several modalities, magnetic resonance imaging (MRI) is currently considered to be the best to measure the 3-dimensional eye shape, and one study using MRI revealed that myopic eyes became much larger in all 3 dimensions, but more so in length (0.35 mm/D) than in height (0.19 mm/D) or in width (0.10 mm/D), which fitted in global and axial elongation models. Another recent study reported that emmetropic retinas were oblate but oblateness decreased with myopia progression. According to a study to evaluate eye shapes in high myopia, although all emmetropic eyes had a blunt shape, almost half of the high myopic eyes had a pointed shape. Multiple lines of evidence suggest that abnormal eye shape changes can cause not only simple myopia but also various ocular complications through biomechanical stretching. In this review, we highlight recent findings on eye shape changes in myopic eyes and abnormal eye shapes in pathologic myopia.
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Lim LS, Chua S, Tan PT, Cai S, Chong YS, Kwek K, Gluckman PD, Fortier MV, Ngo C, Qiu A, Saw SM. Eye size and shape in newborn children and their relation to axial length and refraction at 3 years. Ophthalmic Physiol Opt 2015; 35:414-23. [PMID: 25958972 DOI: 10.1111/opo.12212] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 04/13/2015] [Indexed: 11/26/2022]
Abstract
PURPOSE To determine if eye size and shape at birth are associated with eye size and refractive error 3 years later. METHODS A subset of 173 full-term newborn infants from the Growing Up in Singapore Towards healthy Outcomes (GUSTO) birth cohort underwent magnetic resonance imaging (MRI) to measure the dimensions of the internal eye. Eye shape was assessed by an oblateness index, calculated as 1 - (axial length/width) or 1 - (axial length/height). Cycloplegic autorefraction (Canon Autorefractor RK-F1) and optical biometry (IOLMaster) were performed 3 years later. RESULTS Both eyes of 173 children were analysed. Eyes with longer axial length at birth had smaller increases in axial length at 3 years (p < 0.001). Eyes with larger baseline volumes and surface areas had smaller increases in axial length at 3 years (p < 0.001 for both). Eyes which were more oblate at birth had greater increases in axial length at 3 years (p < 0.001). Using width to calculate oblateness, prolate eyes had smaller increases in axial length at 3 years compared to oblate eyes (p < 0.001), and, using height, prolate and spherical eyes had smaller increases in axial length at 3 years compared to oblate eyes (p < 0.001 for both). There were no associations between eye size and shape at birth and refraction, corneal curvature or myopia at 3 years. CONCLUSIONS Eyes that are larger and have prolate or spherical shapes at birth exhibit smaller increases in axial length over the first 3 years of life. Eye size and shape at birth influence subsequent eye growth but not refractive error development.
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Affiliation(s)
| | - Sharon Chua
- Saw Swee Hock School of Public Health, National University of Singapore, Singapore City, Singapore
| | - Pei Ting Tan
- Biostatistics Unit, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore City, Singapore
| | - Shirong Cai
- Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore City, Singapore
| | - Yap-Seng Chong
- Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore City, Singapore.,Singapore Institute for Clinical Sciences, The Agency for Science, Technology and Research, Singapore City, Singapore
| | - Kenneth Kwek
- Department of Maternal Fetal Medicine, KK Women's and Children's Hospital, Singapore City, Singapore
| | - Peter D Gluckman
- Singapore Institute for Clinical Sciences, The Agency for Science, Technology and Research, Singapore City, Singapore.,Liggins Institute, University of Auckland, Auckland, New Zealand
| | | | - Cheryl Ngo
- Department of Ophthalmology, National University Hospital, Singapore City, Singapore
| | - Anqi Qiu
- Department of Biomedical Engineering, National University of Singapore, Singapore City, Singapore.,Clinical Imaging Research Center, National University of Singapore, Singapore City, Singapore
| | - Seang-Mei Saw
- Singapore Eye Research Institute, Singapore City, Singapore.,Saw Swee Hock School of Public Health, National University of Singapore, Singapore City, Singapore
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Yeh ML, Chen HH, Chung YC. One year study on the integrative intervention of acupressure and interactive multimedia for visual health in school children. Complement Ther Med 2012; 20:385-92. [PMID: 23131368 DOI: 10.1016/j.ctim.2012.09.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 09/07/2012] [Accepted: 09/13/2012] [Indexed: 11/16/2022] Open
Abstract
OBJECTIVE This study used a larger sample size, added a long-term observation of the effect of intervention, and provided an integrated intervention of acupressure and interactive multimedia of visual health instruction for school children. The short- and long-term effects of the interventions were then evaluated by visual health knowledge, visual acuity, and refractive error. DESIGN A repeated pretest-posttest controlled trial was used with two experimental groups and one control group. SETTING Four elementary schools in northern Taiwan. PARTICIPANTS 287 School children with visual impairment in fourth grade were recruited. METHOD One experimental group received the integrative intervention of acupressure and interactive multimedia of visual health instruction (ACIMU), and another received auricular acupressure (AC) alone; whereas a control group received no intervention. Two 10-week interventions were separately given in the fall and spring semesters. The short- and long-term effects of the interventions were then evaluated by visual health knowledge, visual acuity, and refractive error. RESULTS During the school year the visual health knowledge was significantly higher in the ACIMU group than the control group (p<0.001). A significant difference in the changing visual acuity was in the three groups (p<0.001), with the improvement in the ACIMU group. No difference in the refractive error was found between any two groups (p>0.05). CONCLUSIONS This study demonstrated that a long-term period of acupressure is required to improve school children's visual health. School children receiving the intervention of acupressure combined with interactive multimedia had better improvement of visual health and related knowledge than others. Further study is suggested in which visual health and preventative needs can be established for early childhood.
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Affiliation(s)
- Mei-Ling Yeh
- School of Nursing, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan, ROC.
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8
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Dirani M, Chamberlain M, Garoufalis P, Chen C, Guymer RH, Baird PN. Refractive Errors in Twin Studies. Twin Res Hum Genet 2012. [DOI: 10.1375/twin.9.4.566] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
AbstractIt is estimated that 1.6 billion people worldwide have myopia, a refractive error, and this number is expected to increase to approximately 2.5 billion by the year 2020. It is now well established that both the environment and genetics play a role in the development of myopia. However, the exact contribution of each of these components to myopia development has yet to be completely determined. Twin studies (classical twin model) are commonly used to determine the weighting of genetic and environmental components in disease. Over the last century, twin studies have investigated the heritability of refractive errors in different sample populations and have collectively supported a genetic basis to refractive errors. However, different sample populations and methods of data collection have produced a wide range of heritability estimates ranging from .5 to .9. This article will review those twin studies that have investigated refractive error, particularly myopia, as well as biometric measures linked to refractive error, to compare heritability estimates and methodology designs.
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9
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Sanfilippo PG, Hewitt AW, Hammond CJ, Mackey DA. The heritability of ocular traits. Surv Ophthalmol 2010; 55:561-83. [PMID: 20851442 DOI: 10.1016/j.survophthal.2010.07.003] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Revised: 07/23/2010] [Accepted: 07/27/2010] [Indexed: 12/17/2022]
Abstract
Heritability is the proportion of phenotypic variation in a population that is attributable to genetic variation among individuals. Many ophthalmic disorders and biometric traits are known to have a genetic basis and consequently much work has been published in the literature estimating the heritability of various ocular parameters. We collated and summarized the findings of heritability studies conducted in the field of ophthalmology. We grouped the various studies broadly by phenotype as follows: refraction, primary open-angle glaucoma, age-related macular degeneration (AMD), cataract, diabetic retinopathy, and others. A total of 82 articles were retrieved from the literature relating to estimation of heritability for an ocular disease or biometric trait; of these, 37 papers were concerned with glaucoma, 28 with refraction, 4 with AMD, 5 with diabetic retinopathy, and 4 with cataract. The highest reported heritability for an ophthalmic trait is 0.99 for the phenotype ≥ 20 small hard drusen, indicating that observed variation in this parameter is largely governed by genetic factors. Over 60% of the studies employed a twin study design and a similar percentage utilized variance components methods and structural equation modeling (SEM) to derive their heritability values. Using modern SEM techniques, heritability estimates derived from twin subjects were generally higher than those from family data. Many of the estimates are in the moderate to high range, but to date the majority of genetic variants accounting for these findings have not been uncovered, hence much work remains to be undertaken to elucidate fully their molecular etiology.
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Affiliation(s)
- Paul G Sanfilippo
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia.
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Baird PN, Schäche M, Dirani M. The GEnes in Myopia (GEM) study in understanding the aetiology of refractive errors. Prog Retin Eye Res 2010; 29:520-42. [PMID: 20576483 DOI: 10.1016/j.preteyeres.2010.05.004] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Refractive errors represent the leading cause of correctable vision impairment and blindness in the world with an estimated 2 billion people affected. Refractive error refers to a group of refractive conditions including hypermetropia, myopia, astigmatism and presbyopia but relatively little is known about their aetiology. In order to explore the potential role of genetic determinants in refractive error the "GEnes in Myopia (GEM) study" was established in 2004. The findings that have resulted from this study have not only provided greater insight into the role of genes and other factors involved in myopia but have also gone some way to uncovering the aetiology of other refractive errors. This review will describe some of the major findings of the GEM study and their relative contribution to the literature, illuminate where the deficiencies are in our understanding of the development of refractive errors and how we will advance this field in the future.
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Affiliation(s)
- Paul N Baird
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia.
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11
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Lim LS, Gazzard G, Low YL, Choo R, Tan DT, Tong L, Yin Wong T, Saw SM. Dietary Factors, Myopia, and Axial Dimensions in Children. Ophthalmology 2010; 117:993-997.e4. [DOI: 10.1016/j.ophtha.2009.10.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 09/09/2009] [Accepted: 10/01/2009] [Indexed: 12/12/2022] Open
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Estimation of heritability in myopic twin studies. Jpn J Ophthalmol 2009; 53:615-622. [PMID: 20020241 DOI: 10.1007/s10384-009-0724-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Accepted: 04/13/2009] [Indexed: 10/20/2022]
Abstract
PURPOSE To examine the genetic and environmental factors for myopia at the family level, as well as risk factors such as ocular measurements and environmental covariates at the individual level, by analysis of myopic twin data. METHODS A myopic twin study was conducted on participants from the 2000 Guinness World Records for twins in Taiwan. A total of 130 participants comprising 58 twin pairs and 13 siblings were recruited. The generalized estimating equation approach was used to evaluate the covariate effects. A Bayesian linear mixed model was then used to estimate the heritability. RESULTS Pearson's intrapairwise correlation coefficients for ocular refraction and its components were higher among monozygotic twins than among dizygotic twins. The significance of sex suggested that women are more myopic than men. Both axial length and anterior chamber depth were significant factors associated with myopia. The results also showed that people with higher education levels were more likely to have a higher degree of myopia. After accounting for genetic and environmental effects and other covariates, the estimate of heritability of myopia was as high as 0.306. CONCLUSIONS After adjusting for environmental covariates, heritability still plays a decisive genetic role in the development of myopia.
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Khor CC, Grignani R, Ng DP, Toh KY, Chia KS, Tan D, Goh DL, Saw SM. cMET and Refractive Error Progression in Children. Ophthalmology 2009; 116:1469-74, 1474.e1. [DOI: 10.1016/j.ophtha.2009.02.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Revised: 02/25/2009] [Accepted: 02/26/2009] [Indexed: 11/25/2022] Open
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Angi MR, Forattini F, Segalla C, Mantovani E. Myopia evolution in pre-school children after full optical correction. Strabismus 2009; 4:145-57. [DOI: 10.3109/09273979609055050] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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15
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Goldschmidt E. Myopia in humans: can progression be arrested? CIBA FOUNDATION SYMPOSIUM 2007; 155:222-9; discussion 230-4. [PMID: 2088679 DOI: 10.1002/9780470514023.ch13] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The multiplicity of theories regarding the aetiology of myopia has led to numerous and partly contradictory methods of therapy. Interest has been focused on accommodation because of the established association between myopia and close work. In studies of drug treatment of myopia, the treatment is often reported to be effective but the lack of randomization and high drop-out rates make the results questionable. In the Soviet Union, scleral reinforcement is said to be highly successful. Bifocal spectacle lenses reduce the accommodative demand, but studies on the effect of bifocal lenses have shown widely varying results. Whether contact lenses are effective in the control of myopia is still uncertain. In a Danish prospective study on the effect of treatment with bifocal lenses and beta-blocker eye drops a lower rate of progression was found among children wearing bifocal lenses but the difference from the control group was too small to warrant the use of such lenses in every myopic child. The progression rate in the group treated with the beta-blocker timolol maleate was not different from that in the control group. There thus seems to be no simple way of stopping or reducing the progression of myopia. Epidemiological data indicate that the maximum incidences of myopia are associated with educational systems in which the demands on the ability of the child to learn are stringent. One might introduce the term 'ocular stress' but this is clearly difficult to define and even more difficult to measure.
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Affiliation(s)
- E Goldschmidt
- Eye Department O 0821, Danish Institute for Myopia Research, Centralsygehuset Hillerøod, Hillerøod, Denmark
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Hayashi T, Inoko H, Nishizaki R, Ohno S, Mizuki N. Exclusion of Transforming Growth Factor-b1 as a Candidate Gene for Myopia in the Japanese. Jpn J Ophthalmol 2007; 51:96-9. [PMID: 17401617 DOI: 10.1007/s10384-006-0417-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Accepted: 10/04/2006] [Indexed: 10/23/2022]
Abstract
PURPOSE To determine whether single-nucleotide polymorphisms (SNPs) within the transforming growth factor-beta1 (TGF-beta1) gene are associated with high myopia in Japanese. Previous studies have indicated that the gene expression products, regulators of the TGF-beta1 gene, are involved in high myopia. METHODS Genomic DNA samples were obtained from 330 Japanese patients with high myopia and 330 Japanese controls without high myopia who were chosen at random. SNPs were genotyped by the TaqMan system, using primer extension and polymerase chain reaction amplification. RESULTS Ten SNPs were identified in the high-myopia patients and controls, with four of the ten SNPs having nonsynonymous changes. However, no statistical differences in the SNPs were detected between the high-myopia cases and the controls. CONCLUSIONS Sequence variants of the TGF-beta1 gene were not associated significantly with high myopia, and further studies are needed to identify which genes are responsible for high myopia.
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Affiliation(s)
- Takahiko Hayashi
- Department of Ophthalmology, Yokohama City University School of Medicine, Yokohama, Japan.
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Yeh LK, Chiu CJ, Fong CF, Wang IJ, Chen WL, Hsiao CK, Huang SCM, Shih YF, Hu FR, Lin LLK. The Genetic Effect on Refractive Error and Anterior Corneal Aberration: Twin Eye Study. J Refract Surg 2007; 23:257-65. [PMID: 17385291 DOI: 10.3928/1081-597x-20070301-08] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To investigate the role of heredity in determining refractive variables, anterior corneal curvature, and anterior corneal aberrations. METHODS Thirty-three monozygotic and 10 dizygotic twin pairs were enrolled in this study. Corneal curvature, corneal astigmatism, and corneal topography were obtained from computerized videokeratoscope. The CTView program was used to compute anterior corneal aberrations from corneal height data of the videokeratoscope. Correlation analysis was performed to investigate the symmetry of the refractive error, corneal curvature, corneal astigmatism, and anterior corneal aberrations between right and left eyes of each twin pair. Heritability (h2) of these parameters was also calculated. RESULTS Positive correlations were noted between right and left eyes for spherical power, total astigmatism, mean corneal curvature, and corneal astigmatism. In monozygotic twins, vertical coma, secondary vertical coma, spherical aberration, and secondary spherical aberration were moderately correlated. In dizygotic twins, vertical coma, secondary horizontal coma, and spherical aberration were moderately correlated. In unrelated controls, secondary vertical coma, secondary horizontal coma, and secondary spherical aberration were moderately correlated. Root-mean-square (RMS) of higher order aberrations (3rd to 6th orders), RMS of spherical aberration, and RMS of coma were moderately correlated between right and left eyes in all three groups. Heritability of spherical aberration, RMS of spherical aberration, and corneal astigmatism (h2 = 0.56, 0.44, and 0.46) were greater than those of refractive power, corneal curvature, and other higher order aberrations. CONCLUSIONS These results suggest that corneal astigmatism and spherical aberration possess a greater genetic predisposition than those of other refractive errors and higher order aberrations.
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Affiliation(s)
- Lung-Kun Yeh
- Department of Ophthalmology, Chang-Gung University College of Medicine
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Abstract
Myopia is of diverse aetiology. A small proportion of myopia is clearly familial, generally early in onset and of high level, with defined chromosomal localisations and in some cases, causal genetic mutations. However, in economically developed societies, most myopia appears during childhood, particularly during the school years. The chromosomal localisations characterised so far for high familial myopia do not seem to be relevant to school myopia. Family correlations in refractive error and axial length are consistent with a genetic contribution to variations in school myopia, but potentially confound shared genes and shared environments. High heritability values are obtained from twin studies, but rest on contestable assumptions, and require further critical analysis, particularly in view of the low heritability values obtained from parent-offspring correlations where there has been rapid environmental change between generations. Since heritability is a population-specific parameter, the values obtained on twins cannot be extrapolated to define the genetic contribution to variation in the general population. In addition, high heritability sets no limit to the potential for environmentally induced change. There is in fact strong evidence for rapid, environmentally induced change in the prevalence of myopia, associated with increased education and urbanisation. These environmental impacts have been found in all major branches of the human family, defined in modern molecular terms, with the exception of the Pacific Islanders, where the evidence is too limited to draw conclusions. The idea that populations of East Asian origin have an intrinsically higher prevalence of myopia is not supported by the very low prevalence reported for them in rural areas, and by the high prevalence of myopia reported for Indians in Singapore. A propensity to develop myopia in "myopigenic" environments thus appears to be a common human characteristic. Overall, while there may be a small genetic contribution to school myopia, detectable under conditions of low environmental variation, environmental change appears to be the major factor increasing the prevalence of myopia around the world. There is, moreover, little evidence to support the idea that individuals or populations differ in their susceptibility to environmental risk factors.
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Affiliation(s)
- Ian Morgan
- Visual Sciences Group, Research School of Biological Sciences and Centre for Visual Science, Australian National University, GPO Box 475, Canberra City, ACT 2601, Australia.
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19
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Rose KA, Morgan IG, Smith W, Mitchell P. High heritability of myopia does not preclude rapid changes in prevalence. Clin Exp Ophthalmol 2002; 30:168-72. [PMID: 12010207 DOI: 10.1046/j.1442-9071.2002.00521.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The aetiology of myopia is complex, but the major form of myopia results from an interplay between genetic factors and environmental influences. Although there are clear patterns of family inheritance and high heritability values in studies from all over the world,environmental factors are increasingly important in determining myopic outcomes in East Asia, and perhaps elsewhere. This is not paradoxical, as high heritability does not preclude strong environmental influences. The lower heritability values obtained from parent-offspring correlations in populations of East Asian origin where there are marked differences in the environmental exposures (education and urbanization) of parents and children, and where there has been a major shift in the population distribution of myopia, are consistent with this view. Despite the impact of environmental pressures in East Asia, there is evidence that parental myopia influences the position of their offspring within that new population distribution.
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Affiliation(s)
- Kathryn A Rose
- School of Applied VisionScience, Faculty of Health Sciences, University of Sydney, Lidcombe,New South Wales, Australia.
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Saw SM, Nieto FJ, Katz J, Schein OD, Levy B, Chew SJ. Familial clustering and myopia progression in Singapore school children. Ophthalmic Epidemiol 2001; 8:227-36. [PMID: 11471091 DOI: 10.1076/opep.8.4.227.1609] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Familial factors may be related to the progression of myopia in children. A cohort study was conducted to determine the relationship between familial factors and myopia progression in children. METHODS From a larger clinical trial (n = 311), 153 Singapore children aged 6--12 years were recruited to participate in a cohort study of the risk factors for myopia progression. An in-person interview was conducted whereby information on the history of myopia in first-degree relatives was obtained. Other information collected included housing type, parental education and income. Cycloplegic refractive error as measured by subjective refraction and autorefraction were ascertained every six months. The average length of follow-up was 28 months. RESULTS The adjusted mean rate of progression of myopia was -0.60 (95% confidence interval -0.66, -0.55) diopters per year. The average rate of progression of myopia for children with a parental history of myopia was -0.63 (95% confidence interval -0.69, -0.56) diopters per year compared to -0.42 (95% confidence interval -0.57, -0.27) diopters per year for children whose parents were not myopic. The different measures of family history of myopia were related to rate of change in refractive error and refractive error in the final visit. There was no association between close work and myopia progression. CONCLUSIONS A positive family history is related to the progression of myopia and final refractive error in Singapore children, thus supporting evidence that hereditary factors may play an important role in myopia progression.
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Affiliation(s)
- S M Saw
- Department of Community, Occupational and Family Medicine, Faculty of Medicine, National University of Singapore, Singapore.
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21
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Abstract
PURPOSE To find out whether the development of myopia is related to the level of education. MATERIALS AND METHODS From two big ophthalmic outpatient clinics in Jordan, 968 subjects (between the age of 24 and 45 years) were included in this study. A subject was considered myopic if at least one eye had a spherical equivalent refractive error of at least -0.75 diopter. The subjects were divided into two groups: the educated group was those who had finished at least 12 years of education and the non-educated which included those with maximum of six years of education. There were 468 men and 500 women. RESULTS The frequency of myopia was higher in the educated group in both men and women. A significant relationship was found between the level of education and myopia in the whole study group (p<0.0001). CONCLUSIONS This study had too few subjects to draw general conclusions, but within the study group there was a significant relationship between the level of education and the development of myopia.
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Affiliation(s)
- M D Al-Bdour
- Department of Ophthalmology, Jordan University of Science and Technology, Irbid.
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Saw SM, Nieto FJ, Katz J, Chew SJ. Estimating the magnitude of close-up work in school-age children: a comparison of questionnaire and diary instruments. Ophthalmic Epidemiol 1999; 6:291-301. [PMID: 10544343 DOI: 10.1076/opep.6.4.291.4184] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Numerous scientists have noted a relationship between close-up work and myopia. METHODS A questionnaire and four 24-hour diaries were developed to estimate close-up work activity in a cohort study of close-up work and myopia progression in Singapore children. The number of hours per day that children engaged in each type of close-up work activity over a weekday and weekend during the school term, during the examination period, and in the vacation were estimated. RESULTS The children spent an average of 6.6 hours per day on total weighted average close-up work, of which 4.3 hours were spent on reading and writing. The intra-class correlation coefficient for the reproducibility of the questionnaire was 0.87 (95% CI 0.85-0.91). The intra-class correlation coefficient for total weighted close-up work was 0.50 (95% CI 0.34-0.66) when the questionnaire was compared with the four 24-hour diaries. The amount of close-up work activity increased with age. CONCLUSIONS A questionnaire for close-up work was developed and proven to be reproducible and comparable to four 24-hour diaries.
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Affiliation(s)
- S M Saw
- National University of Singapore, Department of Community, Occupational, and Family Medicine, Singapore, Singapore.
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Abstract
As they grow up, approximately 25% of children in the United States become myopic (nearsighted). A much smaller fraction become significantly hyperopic (farsighted), while the majority develop little or no refractive error and are emmetropic. The causes of refractive error, especially myopia, have been the subject of debate for more than a century. Some have held that myopia is primarily an inherited disorder, and others, that myopia is caused by protracted near work and, especially, by accommodation during protracted near work. It has not been possible, based solely on clinical observations, to resolve the relative roles of heredity versus environment in the development of refractive error. In the mid-1970s, several animal models were developed to study the mechanisms underlying refractive error. Using animal models, it was found that the visual environment exerts a powerful influence on refractive state by controlling the axial length of the eye during the postnatal developmental period. Although several species have been examined, three have emerged as primary models and have played complementary roles: tree shrews (mammals closely related to primates), chicks, and monkeys. Each has advantages and disadvantages. Collectively, research on animal models has provided evidence on three issues, namely that (1) the visual environment can produce refractive error; (2) an emmetropization mechanism normally guides eyes to low refractive error; and (3) under-accommodation, rather than excessive accommodation, may cause myopia. Two decades of research on animal models have provided criteria that may be used to evaluate the usefulness of additional species as models of emmetropization.
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Affiliation(s)
- Thomas T. Norton
- Professor in the Department of Physiological Optics, School of Optometry, University of Alabama at Birmingham, Birmingham, Alabama, USA
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Løgstrup N, Sjølie AK, Kyvik KO, Green A. Long-term influence of insulin dependent diabetes mellitus on refraction and its components: a population based twin study. Br J Ophthalmol 1997; 81:343-9. [PMID: 9227196 PMCID: PMC1722189 DOI: 10.1136/bjo.81.5.343] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
AIM To study whether refraction of the eye, or some of its components is influenced by duration of insulin dependent diabetes mellitus. METHODS From the young cohort of the population based Danish Twin Register, containing 20,888 twin pairs born between 1953 and 1982, all twin pairs having one or both partners affected with IDDM were searched. Autorefraction, autokeratometry, and ultrasonic biometric measurements were carried out on 45 twin pairs: 16 monozygotic (MZ) twin pairs, 14 dizygotic twin pairs of same sex (DZss), and 15 dizygotic twin pairs of opposite sex (DZos). To obtain an estimate of the influence of duration of diabetes, the intrapair differences in duration of diabetes were correlated with intrapair differences in refraction and each of its components. RESULTS Refraction was statistically significantly negatively correlated with duration of diabetes in the DZss group, and axial length correspondingly positively correlated. Surprisingly, refraction and axial length in the MZ group, adjusted for confounding factors, were correlated with diabetes duration in the opposite direction than in the DZss group, although not reaching statistical significance. Lens thickness was statistically significantly positively correlated with duration of diabetes in both MZ and DZ twins. Anterior chamber depth was negatively correlated with duration of diabetes in all the zygosity groups. CONCLUSIONS Studies of relations between refraction and duration of diabetes show diverging results. In the MZ group, a tendency to reduced axial length and corresponding hyperopia with increasing duration of diabetes was found. However, in the DZ group of same sex the opposite tendency was found. Increasing lens thickness and decreasing anterior chamber depth with increasing duration of diabetes have been confirmed in this study.
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Affiliation(s)
- N Løgstrup
- Department of Ophthalmology, Odense University Hospital, Denmark
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Løgstrup N, Sjølie AK, Kyvik KO, Green A. Lens thickness and insulin dependent diabetes mellitus: a population based twin study. Br J Ophthalmol 1996; 80:405-8. [PMID: 8695559 PMCID: PMC505489 DOI: 10.1136/bjo.80.5.405] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
AIM To investigate the relation between lens thickness and duration of insulin dependent diabetes mellitus (IDDM). METHODS From the new population based Danish twin register, containing 20,888 twin pairs born between 1953 and 1982 (inclusive), all twin pairs having one or both partners affected with IDDM were searched. Among the 45 twin pairs available for clinical eye examination there were 15 monozygotic pairs, 14 dizygotic pairs of same sex, and 16 dizygotic pairs of opposite sex. Lens thickness was measured by ultrasonography. Using a twin control design, the relation between lens thickness and duration of IDDM was assessed by estimating the correlation between the intrapair difference in lens thickness and the intrapair difference in diabetes duration. RESULTS In monozygotic twin pairs a statistically highly significant correlation between duration of diabetes and lens thickness was found (right eye: r = 0.88, p < 0.0001; left eye: r = 0.90, p < 0.0001). In dizygotic twin pairs of the same sex the correlations were r = 0.58 (p = 0.029) and r = 0.53 (p = 0.053) for right eye and left eye, respectively. For dizygotic twin pairs of opposite sex the correlations were r = 0.58 (p = 0.018) and r = 0.69 (p = 0.005) for right eye and left eye, respectively. The slope in regression analysis were similar for monozygotic twin pairs (0.025, common for both eyes) and dizygotic twin pairs grouped (0.024, common for both eyes). CONCLUSIONS There is a statistically significant positive correlation between duration of IDDM and lens thickness, as assessed by the twin control method. The higher correlation in monozygotic twins compared with dizygotic twins suggests that genetic factors play an additional role in the determination of lens thickness. The similar slopes in regression analysis indicate that the effect of diabetes duration on lens thickness is independent of zygosity.
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Affiliation(s)
- N Løgstrup
- Department of Ophthalmology, Odense University Hospital, Denmark
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Hui J, Peck L, Howland HC. Correlations between familial refractive error and children's non-cycloplegic refractions. Vision Res 1995; 35:1353-8. [PMID: 7610597 DOI: 10.1016/0042-6989(94)00224-a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We examined the spherical equivalent refractions of 237 subjects who had been seen four or more times in a longitudinal study of refractive development in normal children. We employed both photorefraction and autorefraction using a Canon R1 autorefractor. We performed an analysis of variance (F-test for Lack of Fit) to determine the significance of a linear regression in fitting these refractions against three different measures of familial refractive status. One measure included only the number of myopic parents, a second took into account the number of hyperopic parents, and a third included the refractive states of extended genetic relatives. We found no significant correlation between photorefractive data and familial refractions; however, we did find significant, albeit weak, correlations between all measures of familial refractive status and infrared autorefractions of their children. A linear relationship between autorefractive data and overall familial refractive state was found to be most significant. Linear regression of children's autorefractions against a measure of parental myopia and hyperopia was less significant, while a linear model fitting only a measure of parental myopia was least significant, in addition to showing other non-linear trends. We attribute the failure to find a significant correlation between parent and offspring refractions using children's photorefractive data to vignetting by the apparatus and to the short distance of the fixation target. We believe the significant correlation patterns found with the autorefractor reflect the inheritance patterns of parental and familial refractive states.
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Affiliation(s)
- J Hui
- Section of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
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