Refractive Errors in Twin Studies

2006 ◽  
Vol 9 (4) ◽  
pp. 566-572 ◽  
Author(s):  
Mohamed Dirani ◽  
Matthew Chamberlain ◽  
Pam Garoufalis ◽  
Christine Chen ◽  
Robyn H. Guymer ◽  
...  
Keyword(s):  
Data Collection ◽  
Refractive Error ◽  
Genetic Basis ◽  
Twin Studies ◽  
Refractive Errors ◽  
Twin Model ◽  
Wide Range ◽  
Heritability Estimates

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.

An Update on Longitudinal Twin and Family Studies

2007 ◽  
Vol 10 (1) ◽  
pp. 1-2 ◽  
Author(s):  
Meike Bartels
Keyword(s):  
Data Collection ◽  
Behavior Genetics ◽  
Human Genetics ◽  
Longitudinal Research ◽  
Family Studies ◽  
Twin Studies ◽  
Special Issue ◽  
Regular Time ◽  
Wide Range ◽  
Age Cohort

AbstractWith the development of large twin-family registers worldwide (see the December 2006 issue of Twin Research and Human Genetics for an overview) new options for research projects become feasible, including longitudinal studies. In this special issue on Longitudinal Twin and Family Studies, several aspects of longitudinal research are highlighted and an overview of results is given from European, Australian and United States twin studies. These studies deal with a time span from birth to adulthood and a wide range of phenotypes is covered. Data collection in some studies is age/cohort driven; in others, subjects are followed from different ages at regular time intervals. Most studies are based on data collection in twins, but adoption and parent–offspring data designs are described as well. The overview of results of current longitudinal projects makes this special issue a reference resource for longitudinal research in developmental behavior genetics.

Genes and Politics: A New Explanation and Evaluation of Twin Study Results and Association Studies in Political Science

2013 ◽  
Vol 21 (3) ◽  
pp. 350-367 ◽  
Author(s):  
Doron Shultziner
Keyword(s):  
Political Science ◽  
Genetic Basis ◽  
Behavioral Genetics ◽  
Association Studies ◽  
Twin Studies ◽  
Future Research ◽  
Voting Turnout ◽  
Study Results ◽  
Heritability Estimates ◽  
And Function

This article offers a new explanation for the results of twin studies in political science that supposedly disclose a genetic basis for political traits. I argue that identical twins tend to be more alike than nonidentical twins because the former are more similarly affected by the same environmental conditions, but the content of those greater trait similarities is nevertheless completely malleable and determined by particular environments. The twin studies method thus can neither prove nor refute the argument for a genetic basis of political traits such as liberal and conservative preferences or voting turnout. The meaning of heritability estimates results in twin studies are discussed, as well as the definition and function of the environment in the political science twin studies. The premature attempts to associate political traits with specific genes despite countertrends in genetics are also examined. I conclude by proposing that the alternative explanation of this article may explain certain puzzles in behavioral genetics, particularly why social and political traits have higher heritability estimates than common physical and medical traits. I map the main point of disagreements with the methodology and the interpretation of its results, and delineate the main operative implications for future research.

scholarly journals Epidemiological Findings of Refractive Errors and Amblyopia among the Schoolchildren in Hatta Region of the United Arab Emirates

2021 ◽  
pp. 1-7
Author(s):  
Salam Chettian Kandi ◽  
Hayat Ahmad Khan
Keyword(s):  
Visual Acuity ◽  
Visual Field ◽  
United Arab Emirates ◽  
Refractive Error ◽  
Screening Program ◽  
Low Vision ◽  
Refractive Errors ◽  
Vision Screening ◽  
Screening Programs ◽  
School Based

<b><i>Introduction:</i></b> Uncorrected refractive errors and amblyopia pose a major problem affecting schoolchildren. We had previously observed that many schoolchildren in the Hatta region presented to the ophthalmology clinic with uncorrected refractive errors and amblyopia, which led us to undertake this research. As per the WHO, the term “visual impairment” can be “low vision” or “blindness.” Based on the presenting vision, “low vision” is defined for children who have vision of &#x3c;6/18 to 3/60 or having visual field loss to &#x3c;20° in the better-seeing eye. Children defined to have “blindness” have presenting vision of &#x3c;3/60 or corresponding visual field of &#x3c;10°. <b><i>Purpose:</i></b> To estimate the magnitude of uncorrected refractive errors and amblyopia among the schoolchildren aged 6–19 years and to assess the efficacy of school-based refractive error screening programs in the Hatta region of the United Arab Emirates. <b><i>Methods:</i></b> An epidemiological, cross-sectional, descriptive study was conducted on the entire student population studying in the government schools of the region. Those who failed the Snellen visual acuity chart test and those who were wearing spectacles were evaluated comprehensively by the researcher in the Department of Ophthalmology of the Hatta Hospital. Data were entered in the Refractive Error Study in School Children (RESC) eye examination form recommended by the WHO, and were later transferred to Excel sheets and analyzed by SPSS. <b><i>Results:</i></b> 1,591 students were screened and evaluated from the end of 2016 to mid-2017. About 21.37% (<i>n</i> = 340) had impaired vision with 20.9% (<i>n</i> = 333) refractive errors, of which 58% were uncorrected. Among the refractive error group, 19% (64 subjects) had amblyopia (4% of total students). The incidence of low vision was 9.5% and blindness was 0.38%. Low vision was found to be 9.5% and blindness 0.38%, taking in to account presenting visual acuity rather than best-corrected visual acuity for defining low vision and blindness. <b><i>Conclusion:</i></b> A significant number of students were detected to have uncorrected refractive errors among the vision impaired group (59%, <i>n</i> = 197) despite a school-based vision screening program in place. Seventy-eight percent of the amblyopia cases (<i>n</i> = 50) were found to be in the 11–19 years age group. Noncompliance with optical corrections was the reason for the high number of cases. A rigorous vision screening program and refractive services, complimented with awareness among parents and teachers, are recommended.

The prevalence and causes of visual impairment in Dariyah, a rural community in Saudi Arabia

2021 ◽  
Vol 80 (1) ◽  
Author(s):  
Waleed Alghamdi ◽  
Godwin O. Ovenseri-Ogbomo
Keyword(s):  
Saudi Arabia ◽  
Visual Impairment ◽  
Rural Community ◽  
Refractive Error ◽  
Population Based ◽  
Vision Impairment ◽  
Health Examination ◽  
Refractive Errors ◽  
Cross Sectional ◽  
Eye Examination

Background: Visual impairment is disproportionately distributed between rural and urban dwellers. Rural dwellers have limited access to the eye care services that are available in urban cities.Aim: The aim of this study was to determine the prevalence and causes of visual impairment in Dariyah, a rural community in the Qassim region, Saudi Arabia.Setting: This research comprised a population-based assessment of the vision and visual status of the inhabitants of Dariyah community.Methods: A cross-sectional descriptive study was conducted amongst the inhabitants of the community of Dariyah. A comprehensive eye examination consisting of visual acuity, ocular health examination, objective and subjective refraction was performed. The examinations were conducted by registered ophthalmologists and optometrists from the Qassim University. Vision impairments were categorised according to the International Classification of Diseases (ICD), Section 9D90, ‘Vision impairment including blindness’ (2018).Results: In all, 68 (24.5%) participants had vision impairment (using the better-seeing eye), with refractive errors being the main cause of vision impairment. Other causes of vision impairment included cataract (20, 7.2%), trichiasis (5, 1.8%) and glaucoma (2, 0.7%). Refractive errors were present in 193 (69.7%), with astigmatism being the commonest refractive error. About 60% of those with refractive errors presented without spectacles for correction, and 20% reported that they had never had an eye examination. Refractive errors could not be determined in 19 (6.9%) of the subjects because of conditions such as matured cataract and other ocular abnormalities.Conclusion: Uncorrected refractive error was found to be the leading cause of vision impairment in this rural community in Saudi Arabia.

Evaluation of CORSIM Car-Following Model by Using Global Positioning System Field Data

2000 ◽  
Vol 1710 (1) ◽  
pp. 114-121 ◽  
Author(s):  
Sastry Chundury ◽  
Brian Wolshon
Keyword(s):  
Data Collection ◽  
Global Positioning System ◽  
Field Data ◽  
Goodness Of Fit ◽  
Positioning System ◽  
Goodness Of Fit Test ◽  
Distance Information ◽  
Car Following ◽  
Wide Range ◽  
Global Positioning

It has been recognized that CORSIM (and its constituent program, NETSIM) is one of the most widely used and effective computer programs for the simulation of traffic behavior on urban transportation networks. Its popularity is due in large part to the high level of detail incorporated into its modeling routines. However, the car-following models, used for the simulation of driver behavior in the program, have not been formally calibrated or validated. Since the model has performed well in a wide range of applications for so many years, it has always been assumed to have an implied validity. This study evaluated the NETSIM car-following models by comparing their results with field data. Car-following field data were collected using a new data collection system that incorporates new Global Positioning System and geographic information system technologies to improve the accuracy, ease, speed, and cost-effectiveness of car-following data collection activities. First, vehicle position and speed characteristics were collected under field conditions. Then simulated speeds and distances were based on identical lead vehicle actions using NETSIM car-following equations. Comparisons of simulated and field data were completed using both graphical and statistical methods. Although some differences were evident in the graphical comparisons, the graphs overall indicated a reasonable match between the field and simulated vehicle movements. Three statistical tests, including a goodness-of-fit test, appear to support these subjective conclusions. However, it was also found that definitive statistical conclusions were difficult to draw since no single test was able to compare the sets of speed and distance information on a truly impartial basis.

scholarly journals Case Report: Serial Topography Analysis After Acute Unilateral Diffuse Lamellar Keratitis

2020 ◽  
Vol 82 (3) ◽  
pp. 19-24
Author(s):  
Jonathan Jay Lytle
Keyword(s):  
Case Report ◽  
Refractive Error ◽  
Clinical Signs ◽  
Corneal Topography ◽  
Laser In Situ Keratomileusis ◽  
Refractive Errors ◽  
Fort Worth ◽  
Topical Corticosteroids ◽  
Gross Examination

Abstract Significance: Diffuse lamellar keratitis (DLK) is a widely reported complication of laser in-situ keratomileusis (LASIK); however, serial topography tracking the resolution of the condition is sparse. This case illustrates the healing profile which may be expected following an episode of DLK, and the patient reassurances which may be appropriate. Purpose: To report the topography changes and refractive resolution associated with a case of acute unilateral diffuse lamellar keratitis following bilateral femtosecond-assisted hyperopic LASIK. Case Report: A healthy 53-year old male presented with grade two-plus diffuse lamellar keratitis (DLK) 11 days after undergoing successful bilateral wavefront optimized (Alcon, Fort Worth, USA), femtosecond-assisted hyperopic LASIK. Resolution of the DLK was achieved in three weeks with topical corticosteroids. Stabilization of the patient’s topography and refractive error was observed two months after the resolution of the DLK. Conclusions: This case suggests that improvements in corneal topography and refractive error can be expected long after the clinical signs of DLK have subsided. Corneal irregularities and residual refractive errors (usually hyperopia and astigmatism) which exist at the time of resolution on gross examination should be monitored regularly and patients may be reassured that improvements appear likely even after topical regimens have been completed.

scholarly journals ARKEOFAUNA KAWASAN KARST BONTOCANI KABUPATEN BONE SULAWESI SELATAN

2018 ◽  
Vol 16 (1) ◽  
pp. 21
Author(s):  
Nfn Fakhri
Keyword(s):  
Data Collection ◽  
Environmental Change ◽  
Comparative Studies ◽  
Rain Forest ◽  
Data Availability ◽  
Karst Area ◽  
Forest Environment ◽  
Faunal Composition ◽  
Wide Range ◽  
Bone Fragments

This study aims to provide a description of the fauna that once interacted with a human in the Bontocani karst Area in Bone District. Of the few excavated sites providing data availability of bone fragments that can be analyzed by conducting comparative studies with existing faunal composition of the fauna. The method of data collection is by excavation at some sites in this Karst Area. The results of this study document a wide range of vertebrates in the Balang Metti fauna including fish, frogs/toads, lizards, snakes, birds, Strigocuscus, Ailurops ursinus, insectivorous bats, Sulawesi monkeys, rats, Sulawesi pigs, babirusa and Anoa. In some layers of culture, the absence of anoa, indicates the environmental change from the environment of the fields and the weeds to the wet rain forest environment around the site, along with the extinction of this fauna. Based on the identified fauna bone analysis, it is illustrated that past habitats and environments in Bontocani Karst area have not changed much. Penelitian ini bertujuan memberikan gambaran secara lebih jelas tentang fauna-fauna yang pernah berinteraksi dengan manusia pendukung kebudayaan yang ada di Kawasan Karst Bontocani di Kabupaten Bone. Beberapa situs yang telah diekskavasi memberikan ketersediaan data berupa fragmen tulang yang dapat dianalisis dengan melakukan studi komparasi dengan komposisi tulang fauna yang ada saat ini. Metode pengumpulan data yang dilakukan adalah dengan ekskavasi di beberapa situs yang ada di Kawasan Karst ini. Hasil penelitian menunjukkan bahwa sebagian besar jenis fauna yang ditemukan di situs ini adalah fauna bertulang belakang antara lain: ikan, kodok/katak, kadal, ular, burung, strigocuscus, Ailurops ursinus, kelelawar pemakan serangga, monyet sulawesi, tikus, babi sulawesi, babi russa dan anoa. Pada beberapa lapisan budaya, tidak adanya temuan fauna anoa, menunjukkan perubahan lingkungan dari lingkungan padang dan ilalang menjadi lingkungan hutan hujan basah di sekitar situs, seiring dengan punahnya fauna ini. Berdasarkan analisis tulang fauna yang berhasil diidentifikasi digambarkan bahwa habitat dan lingkungan masa lampau di Kawasan Karst Bontocani tidak banyak mengalami perubahan.

Prevalence and Determining Factors Of Refractive Errors Among Medical Students In FMU, Faisalabad

2021 ◽  
Vol 15 (11) ◽  
pp. 2934-2935
Author(s):  
Nadia Tufail ◽  
Huda Abbas ◽  
Ali Sarfraz ◽  
Sumaira Ashraf ◽  
M. Ashraf Majrooh
Keyword(s):  
Medical Students ◽  
Mobile Phone ◽  
Mobile Phones ◽  
Refractive Error ◽  
Contact Lenses ◽  
Electronic Devices ◽  
Quantitative Information ◽  
Refractive Errors ◽  
Cross Sectional ◽  
Determining Factors

Aim: Prevalence and determining factors of refractive errors among the medical students in FMU, Faisalabad. Methodology: Cross-sectional quantitative study conducted in Faisalabad Medical University from 01-03-2020 to 15-12-2020 after approval from institutional review committee. All students of MBBS in FMU were included in this study. A structured questionnaire was used to collect the required quantitative information. SPSS version 26 was used for analysis. Results: Prevalence of refractive error is 49%. Females were 59% and males were 41%. More students i.e. 85.2% were suffering from myopia. In our study, usage of electronic devices i.e. mobile phones especially was one of the risk factors in developing refractive errors. 20.6% students having refractive error said that they use mobile phone for 4 hours, 30.2% having refractive error said that they watch TV for one hour, 23.3% having refractive error said that they play video games for one hour. For the correction of the refractive error, 184 students i.e. 97.4% used spectacles whereas only 5 (2.6%) students used contact lenses. It is observed in this study that contact lenses were only used by those students having refractive error <1.5. Conclusion: Refractive errors were a significant cause of visual impairment among medical students. The prolonged use of electronic devices especially mobile phones should be discouraged. Keywords: Refractive errors, myopia, electronic devices, mobile phone

Addressing Data Collection Challenges in ICT for Development Projects

2015 ◽  
Vol 7 (3) ◽  
pp. 36-55 ◽  
Author(s):  
Devendra Dilip Potnis
Keyword(s):  
Developing Countries ◽  
Data Collection ◽  
Lessons Learned ◽  
Time Cost ◽  
Marginalized Communities ◽  
The Past ◽  
Success Stories ◽  
Wide Range ◽  
Collection Data ◽  
Ict For Development

This paper equips researchers for addressing a wide range of data collection challenges experienced when interacting with marginalized communities as part of ICT4D projects in developing countries. This secondary research categorizes data collection challenges reported in multiple disciplines, and summarizes the guidance from the past literature to deal with the challenges. The open, axial, and selective coding of data collection challenges reported by the past literature suggests that it is necessary to manage scope, time, cost, quality, human resources, communication, and risks for addressing the data collection challenges. This paper illustrates the ways to manage these seven dimensions using (a) the success stories of data collection in the past, (b) the lessons learned by researchers during data collection as documented by the past literature, and (c) the advice they offer for collection data from marginalized communities in developing countries.

scholarly journals Refractive Errors and its Associated Factors among Undergraduate Medical Students in Kathmandu

2019 ◽  
Vol 21 (1) ◽  
pp. 26-30
Author(s):  
Aparna Rizyal ◽  
JS Sunrait ◽  
A Mishal
Keyword(s):  
Medical Students ◽  
Visual Impairment ◽  
Refractive Error ◽  
Single Point ◽  
Cross Sectional Study ◽  
Refractive Errors ◽  
Undergraduate Medical Students ◽  
Cross Sectional ◽  
Parental History ◽  
Medical College

 Refractive error is a defect in the optical system of the eye which prevents light from being brought to a single point focus on the retina, thus reducing normal vision. This optical defect is the second most common cause of visual impairment globally as well in Nepal. At present, there are 285 million visually impaired people in the world. An estimated 4 out of 5 visual impairment (80%) can be prevented or cured, uncorrected refractive errors are the leading cause (42%) followed by cataract (33%). A descriptive cross sectional study was conducted to determine the proportion of undergraduate medical students with refractive errors in Nepal Medical College, and to identify factors associated with it. A total of 210 medical students volunteered for this study, with 100 males (47.6%) and 110 females (52.4%). The age of these students were between 18 to 26 years, with an average of 20.5 years. The proportion of medical students with refractive error was slightly more than half (51.4%), with simple myopia being the leading type (42.9%), followed by astigmatism (7.1%) and simple hypermetropia (1.4%). Parental history of refractive error was observed to be significantly associated with that of the medical students. There was also a significant association between refractive error and the daily use of mobile phones and laptops. However, years spent in medical education were not observed to be significant.

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