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1
Smith, Kyla M. "Field measures of refractive error /." Adobe Acrobat Reader required to view document, 2008. http://library.neco.edu/theses/SmithThesisMay08.pdf.
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Ng, Siu-chun Danny, and 吳兆駿. "The prevalence of refractive error and visual impairment caused by uncorrected refractive error in China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B4804331X.
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Purpose: WHO reports 46% of world vision impairment from refractive error (RE)
among children occurs in China. We estimated RE prevalence and associated vision
impairment (VI) among Chinese children and adults.
Methods: Data from population-based studies were stratified by gender in age intervals
of 3 years (ages 3-17 y) or 10 years (ages >= 30 y): counts of persons with myopia
(worse eye spherical equivalent <= -1.0D, <= -2.0D, <= -6.0D) and prevalence of low
vision (< 6/12 in the better-seeing eye for children and < 6/18 for adults) and blindness
(<=6/60) attributable to RE. Figures for VI included persons with habitual vision below
the cutoff improving to above the cutoff with refraction, and those with myopic
retinopathy. Estimates for ages 18-29 y were obtained from regression models derived
from the pooled estimates. Prevalence of myopia and VI attributable to RE in each
age/gender category was calculated by applying modeled rates to 2000 China census
figures and projections for 2020. Association with VI attributable to RE was tested for:
gender, urban versus rural residence, and residence in provinces with per capita GDP in
the upper versus lower 50% for China.
Results: Data were obtained from 5 cohorts for children and 14 for adults. There were
291 million and 21.4 million persons with myopia <= -1.0D and <= -6.0D respectively in
2000, expected to rise to 306 million and 36.9 million by 2020. Of these, 18.4 million
were blind and 116 million had low vision in 2000, with figures of 25.3 million and 123
million in 2020. Children accounted for the following proportion of RE disease burden in
China in 2000: myopia <= -1.0D: 19.0%; RE-associated low vision: 56.1%; blindness:
14.1%. Refractive error was responsible for 82.3% of blindness and 90.5% of low vision
among children, and 11.6% and 64.4% of blindness and low vision among adults. Urban
residence (OR 1.85, P = 0.004) and higher GDP (OR 10.6, P < 0.001) were associated
with refractive blindness among children. For adults, lower GDP was associated with
refractive blindness (OR 1.47, P = 0.01). Gender was un-associated with refractive
blindness among children or adults.
Conclusions: Both children and adults suffer a heavy burden of VI associated with RE in
China. Income may affect risk for such VI differently among children and adults.<br>published_or_final_version<br>Public Health<br>Master<br>Master of Public Health
3
Marks, Amanda R. "Nutrition, Vitamin D and Refractive Error." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1275397144.
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Hartwig, Andreas. "The influence of optics, peripheral refraction and posture on refractive error development." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/the-influence-of-optics-peripheral-refraction-and-posture-on-refractive-error-development(f0382767-3194-4631-8cab-d473d64900bd).html.
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The aim of the present project was to analyse the link between peripheral posture, optics, optics and refractive error progression. Preliminary studies were conducted to ensure that peripheral aberrometry is valid for further analysis. The repeatability of the IRX-3 for peripheral aberrometry was asgood as for central measurements and the recalculation of elliptical pupils did not seem to be necessary for measurements up to 20 degrees eccentricity. Higher order aberration measurements werecomparable to other studies. Eye and head movements as well as working distance did not differ significantly between myopes and non-myopes. However, there was some evidence, that forward bending of the head during reading increases in association with higher refractive error progression rates. The link between central higher order aberrations and refractive error development was analysed by comparing higher order aberrations between isometropes and anisometropes. This analysisdid not show any significant association of higher order aberrations on the development, as no major differences were found between the two groups. For central vision, changes in biometric parameters during accommodation were analysed. It was found that biometric parameters change similarly in myopes and non-myopes. Peripheral accommodation was found to differ between myopes and emmetropes indicating that there might be an influence of peripheral refraction on myopisation. However, associationbetween peripheral refraction or peripheral aberrations and refractive error progression were not significant. The reason for this observation might be the low refractive error progression (0.04± 0.29 D in myopes and -0.12 ± 0.38 D in emmetropes) during one year in the study population.
5
Shah, Rupal Lalit. "Discovery of genetic determinants for refractive error." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/114602/.
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Refractive errors such as myopia are the leading cause of reversible visual impairment worldwide with their prevalence rapidly increasing, resulting in greater burden on public health services. The aim of this series of investigations was to leverage the latest statistical methods and large-scale cohorts available in order to develop our understanding of the genetic determinants for the refractive error traits of spherical equivalent, corneal astigmatism and refractive astigmatism. Investigation of genetic variants on the X-chromosome, a region often neglected in genome-wide association studies (GWAS), identified four genes demonstrating association in a gene-based analysis of spherical equivalent for a cohort of teenagers. Meta-analysis of GWAS results for corneal astigmatism including European and Asian ancestry cohorts performed on behalf of the CREAM consortium successfully replicated the previously identified association near the PDGFRA gene (lead variant: rs7673984, odds ratio = 1.12, P = 5.55 × 10−9). The availability of data from the UK Biobank facilitated the largest GWAS for corneal and refractive astigmatism performed to date (N = 86,335 and 88,005 respectively). Here, GWAS for these traits identified four and two novel loci associated with corneal and refractive astigmatism respectively. Each of these loci had previously been associated with other ocular traits including myopia. Phenotypic variance explained by common genetic variants was relatively low for corneal and refractive astigmatism at ~6% and ~5% respectively, thus proposing a greater role for rare variants in explaining astigmatism variance due to genetics. Lastly, in order to link identified variants and genes functionally influenced in myopia development, several candidate myopia genes identified from a primate myopia model demonstrated enrichment with refractive error associated variants in human samples. Overall, the findings from these investigations are a starting point in guiding further research into the complex biological mechanisms underlying refractive error development.
6
Graham, Nicholas Dale. "The Heritability of Refractive Error between Siblings." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1275350173.
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Smith, Molly J. "Peripheral Refractive Error in Multifocal Contact Lenses." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1460470062.
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McBrien, N. A. "The relationship between accommodation responses and refractive error." Thesis, Cardiff University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376826.
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Merchea, Mohinder Mohan. "Refractive error shift with continuous use (Rescu) lenses." Connect to this title online, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1054652868.
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Thesis (Ph. D.)--Ohio State University, 2003.<br>Title from first page of PDF file. Document formatted into pages; contains xv, 144 p.; also includes graphics (some col.) Includes bibliographical references (p. 129-144). Available online via OhioLINK's ETD Center
10
Kearney, Stephanie. "Myopia : the association between environmental factors and refractive error." Thesis, Ulster University, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.725340.
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O'Donoghue, Elizabeth Ann. "Epidemiology of refractive error in a United Kingdom Child Population." Thesis, University of Ulster, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.529548.
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Breslin, Karen Margaret Mary. "A prospective study of refractive error amongst Northern Irish schoolchildren." Thesis, University of Ulster, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.587479.
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Prospective data on refractive error in childhood in the United Kingdom are scarce. The Northern Ireland Childhood Errors of Refraction Study (NICER Study) is the first prospective population-based investigation of refractive error and ocular components amongst school children in the United Kingdom. The NICER Study (Phase 1) on the prevalence of refractive error amongst Northern Irish schoolchildren began in 2006. This population-based cross-sectional study's primary aim was to investigate the prevalence of myopia in a white population which is reflective of the Northern Irish population. This study had several strengths including the use of stratified random-cluster sampling to identify participants and the use cycloplegia for the measurement of refractive error. Within the NICER Study (Phase 1), data collection was completed on over 1000 schoolchildren. Following on from this, Phase 2 of the study aimed to collect follow-up data on these same subjects three years on from the original data collection. This resulted in a prospective population-based investigation of refractive error amongst primary and post-primary schoolchildren. This allowed both an investigation of the change in prevalence of refractive errors and also the change in individual's refractive error. Protocols remained unchanged between Phase 1 and 2 apart from the inclusion of two additional measures at Phase 2. The study was completed within the time-frame and within budget. Good participation rates were achieved and baseline comparisons between those who participated at Phase 1 and those who participated at Phase 2 showed negligible differences. In total 738 school children were examined (302 9-10-year-olds and 436 15-16-year-olds). Median three-year change in right eye (RE) spherical equivalent refractive error (SER) was - 0.38D amongst 9-10-year-olds and -0.13D amongst 15-16-year-olds. Median three-year change in RE axial length (AL) was 0.48mm amongst 9-10-year-olds and O.l4mm amongst 15-16-year-olds. Low hyperopic refractive error at 9-10-years of age and at 15-16-years-of- age was identified as an ocular predictor for future myopia. Further three year follow-up of the NICER subjects is planned (Phase 3) and this will provide additional prospective data on refractive error during the school years.
13
Sharma, Abhishek. "Xichang paediatric refractive error study (X-PRES), A pilot study." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.510222.
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Andersen, Courtney Erin. "Validation and Repeatability of Pediatric Refractive Error Profile 2 (PREP2)." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1363117173.
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Mulvihill, Shane. "Light Exposure, Refractive Error, and Red and Blue Light-Driven Pupillary Responses." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1460742215.
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Stewart-Bates, Emma. "Proportion of Myopia among Youth Athletes across Different Sports and Locations." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595454796826532.
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Lehman, Joseph Christian. "Sphero-cylindrical Refraction with Spherical Lenses." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587510615809807.
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Parkinson, Annette. "Ocular biometric change in orthokeratology : an investigation into the effects of orthokeratology on ocular biometry and refractive error in an adult population." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/6328.
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Aim: This study looks at the effect of orthokeratology on a number of biometric parameters and refractive error in an adult population. Method: Forty three myopic subjects were recruited to a twelve month study into the effects of orthokeratology on ocular biometry and refractive error. Two different back surface lens designs were applied right eye) pentacurve and left eye) aspheric. The aspheric design was chosen to more closely mimic the cornea's natural shape. Anterior and posterior apical radii and p-values; corneal thickness and anterior chamber depth were measured using the Orbscan IIz; together with ocular biometry by IOL Master and a standard clinical refraction. All measurements were repeated at one night, one week, one, three, six and twelve months. Refractive changes were analysed against biometric changes. Results: Twenty seven participants completed one month of lens wear. Twelve subjects completed twelve months of lens wear. Subjects with myopia ≤ -4.00DS were successfully treated with orthokeratology. Both anterior and posterior apical radii and p values were altered by orthokeratology. Corneal thickness changes were in agreement with previously published studies. Axial length and anterior chamber depth were unaffected by the treatment. Conclusion: Orthokeratology should be available as an alternative to laser refractive surgery. It is best restricted to myopes of up to -4.00DS with low levels of with the rule corneal astigmatism. The use of an aspheric back design contact lens did not produce a significant benefit over that of a pentacurve.
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Beverage, Jacob Lee. "Measuring refractive error in the human eye using a Shack-Hartmann-based autorefractor." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/298729.
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The oldest and most prevalent optical system in the world is the human eye. Variations in the anatomical structure of the eye can cause errors in its optical performance, which in turn lead to errors in the overall performance of the visual system. Fortunately, these refractive errors can be measured and then corrected externally with spectacles, contact lenses, or refractive surgery. This dissertation describes the design, fabrication, and testing of a new autorefractor that can be used to objectively measure human refractive error. The new autorefractor is based on Shack-Hartmann wavefront sensing techniques and uses a novel, Fourier transform-based algorithm to estimate refractive error. The Fourier-based data analysis models the wavefront aberration as a combination of defocus and astigmatism only, expresses the simplified wavefront in terms of measurable quantities in Fourier-space, and relates the coefficients describing the wavefront to the patient's refraction. The Shack-Hartmann-based autorefractor (SHAR) is designed to be inexpensive and compact to facilitate its transition to a commercial device. It represents a significant improvement in automated clinical refraction because it can make accurate measurements of a wide range of refractive errors without relying on moving parts or the intensity of light reflected off the retina. To evaluate its performance, the SHAR was compared to the gold-standard among current commercially available autorefractors in a study of human refractive errors. The results from this limited study population suggested that the SHAR has the potential to perform at least as well as the commercial standard autorefractor.
20
Saigal, Richa. "The role of altered ciliary muscle morphology in refractive error and accommodative function." Thesis, Aston University, 2016. http://publications.aston.ac.uk/30076/.
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The primary theme of this thesis was to investigate in vivo ciliary muscle morphology in refractive error, and how ciliary muscle parameters are linked with accommodative function in a young adult population. Anterior segment optical coherence tomography was utilised for all ciliary muscle image acquisition to examine morphological differences between eyes. High levels of inter-ocular ciliary muscle symmetry were shown in emmetropes and myopes. Whilst the myopic ciliary muscle was longer and thicker than in emmetropes for both eyes, ciliary muscle length and thickness were linked with axial length in both cohorts. In amblyopes and anisometropes, high levels of inter-eye ciliary muscle symmetry were observed. The ciliary muscle in amblyopic eyes appear to grow in accordance with the axial length of the non-amblyopic eye (P = 0.022, r2 = 0.438). The possibility of diurnal variation in accommodative axial elongation and accommodative error was explored in emmetropes and myopes. Daily stability in these accommodative functions were shown, and between groups there was no difference in accommodative axial elongation (P = 0.884) or accommodative error (P = 0.098). It was demonstrated that ciliary muscle morphology is not linked with accommodative function, disputing the theory that the thickened ciliary muscle has reduced contractility, which initiates hyperopic defocus in myopigenesis. In emmetropes, males had significantly longer ciliary muscle lengths (P = 0.031) and axial length (P = 0.001) compared with females. Novel parameters to analyse the ciliary muscle were investigated; both inner apical angle and ciliary muscle cross-sectional area measures were linked to axial length, as were the area and apical angle. Both measures are highly effective ciliary muscle analysis parameters which demonstrated high repeatability. The studies detailed demonstrated normal ciliary muscle growth with ocular development in myopia, and indicated that the ciliary muscle is not a crucial causative myopigenesis factor.
21
Beckett, David Beckett. "The Effect of Light Exposure and Refractive Error on Post-Illumination Pupil Responses." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu152347133666468.
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Orr, Janis B. "Optical and biometric characteristics of the eye and their relationship to refractive error." Thesis, Glasgow Caledonian University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.601635.
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Refractive error, particularly myopia, is a significant visual problem considered to result from a complex interplay between genetics and environmental influences. While there has been a worldwide increase in the prevalence of myopia in recent years, the aetiology of myopia is not yet known. Emmetropisation is the process of normal eye growth during development such that refractive error stabilises at, or close to, emmetropia. This has been shown to be an active process influenced by the visual environment. Previous animal studies have shown that emmetropisation can be disrupted by introducing abnormal optical factors into the central and/or peripheral visual field. Differences in the optical and biometric properties of the emmetropic, myopic, and hyperopic eye have previously been found. The aim of this thesis was to extend previous work by investigating several important biometric and optical characteristics, in emmetropic, myopic and hyperopic eyes, in order to establish any systematic refractive group differences, which may explain the failure of the emmetropisation process. The results presented in this thesis show clear differences between the shape and refractive characteristics of the peripheral retina between myopic, emmetropic and hyperopic subjects. These results suggest that refractive error group dependent differences in the peripheral retina could be a key correlate of refractive error development. Optical properties of the eye, specifically pupil diameter, monochromatic higher order aberrations, and chromatic aberration were shown not to vary significantly between refractive groups, suggesting that these factors are unlikely to play any major role in the development of myopia. It could be, however, that the optical properties of the eye are a consequence of myopia development. Alternatively, the optical properties of the eye vary before myopia develops, or reaches adult levels.
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Schultz, Kristin E. "Accommodative microfluctuations, crystalline lens tension, ciliary body thickness, and refractive error in children." Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1240445960.
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Ernst, Lauren E. "Ciliary Body Thickness and the Relationship to Refractive Error and Accommodative Function in Adults." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1271097119.
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Scher, Aaron David. "Microstrip post production tuning bar error and compact resonators using negative refractive index metamaterials." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2337.
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In this thesis, two separate research topics are undertaken both in the general area
of compact RF/microwave circuit design. The first topic involves characterizing the
parasitic effects and error due to unused post-production tuning bars. Such tuning bars
are used in microwave circuit designs to allow the impedance or length of a microstrip
line to be adjusted after fabrication. In general, the tuning bars are simply patterns of
small, isolated sections of conductor adjacent to the thru line. Changing the impedance
or length of the thru line involves bonding the appropriate tuning bars to the line.
Unneeded tuning bars are simply not removed and left isolated. Ideally, there should be
no coupling between these unused tuning bars and the thru line. Therefore, the unused
tuning bars should have a negligible effect on the circuit??s overall performance. To
nullify the parasitic effects of the tuning bars, conventional wisdom suggests placing the
bars 1.0 to 1.5 substrate heights away from the main line. While successful in the past,
this practice may not result in the most efficient and cost-effective placement of tuning
bars in today??s compact microwave circuits. This thesis facilitates the design of compact
tuning bar configurations with minimum parasitic effects by analyzing the error
attributable to various common tuning bar configurations with a range of parameters and
offset distances. The error is primarily determined through electromagnetic simulations,
and the accuracy of these simulations is verified by experimental results. The second
topic in this thesis involves the design of compact microwave resonators using the
transmission line approach to create negative refractive index metamaterials. A survey
of the major developments and fundamental concepts related to negative refractive index
technology (with focus on the transmission line approach) is given. Following is the
design and measurement of the compact resonators. The resonators are also compared to
their conventional counterparts to demonstrate both compactness and harmonic
suppression.
26
Orr, Danielle Jean. "The Effect of Refractive Error and Light Exposure on Red and Blue Light-Driven Pupil Responses." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1491935483251647.
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Armstrong, Deborah. "The Role of vision and refractive correction changes in dizziness." Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/16956.
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Dizziness is a common, multifactorial problem that causes reductions in
quality of life and is a major risk factor for falls, but the role of vision is a very
under-researched area. This study aimed to investigate any link between
dizziness and vision and to establish if changes in spectacle lens correction
could elicit dizziness symptoms.
A link between dizziness and self-reported poor vision was indicated in the
epidemiological literature as shown by a systematic review, provided lightheadedness
was not included in the definition of dizziness. Cases of
individuals who reported vision-related dizziness were investigated to
determine potential areas of research for this thesis and subsequently two
studies investigated the effects of refractive correction changes on dizziness
status. The first study was limited by logistical problems, although it
highlighted limitations in the short form of the Dizziness Handicap Inventory
that was used to quantify dizziness. Results of an optometry practice recheck
study found that oblique cylindrical changes were significantly more likely to
be associated with dizziness symptoms than other spectacle lens changes. It
also highlighted that optometrists do not ask/record about dizziness symptoms
with only 4% of records including “dizziness” as a problem when 38% of
patients reported dizziness symptoms when directly asked. All studies
highlighted a need for a patient-reported outcome measure to be designed to
assess vision-related dizziness. Literature review, interviews with experts and
patients and focus groups led to the development of a pilot questionnaire and
subsequently a 25-item Vision-Related Dizziness instrument, the VRD-25.
This was validated using responses from 223 respondents, with 79
participants completing the questionnaire a second time to provide test-retest
data. Two subscales of VRD-12-frequency (VRD-12f) and VRD-13-severity
(VRD-13s) were shown to be unidimensional and had good psychometric
properties, convergent validity and test-retest repeatability. The VRD-25 is the
only patient-reported outcome measure developed to date to assess vision related
dizziness and will hopefully provide the platform to further grow this
under-researched area that seems likely to provide important clinical
information.<br>College of Optometrists sponsored the research with a Postgraduate Research Scholarship
28
Locke, Christina. "In vivo cone photoreceptor imaging in adolescents as a measure of retinal stretch during refractive error development." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1554723728663165.
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Morgan, Kelly M. "The Effect of Refractive Error and Time Spent Outdoors on Red and Blue Light-Driven Pupil Responses." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555351799339715.
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Barsha. "Optical coherence tomography angiography assessment of retinal and choroidal vasculature: Diurnal and longitudinal changes and refractive error." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/236553/1/Barsha%2BThesis%281%29.pdf.
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This research measured normal short-term, diurnal, changes, and longer-term changes across a year, in retinal and choroidal blood vessels, using optical coherence tomography angiography (OCT-A). It is the first research to show significant diurnal changes in retinal and choroidal OCT-A indices in healthy young adults, changes that differed between myopic and non-myopic patients. It also found that retinal OCT-A indices changes across a year in children but not adults. OCT-A measures of choroidal blood vessels were stable across the year in both adults and children. These findings benchmark normal OCT-A changes across time and have scientific and clinical value.
31
Coates, Zachary Alan. "Contact Lens, Academics, and Self-Perception (CLASP) Study: Study Design and Initial Results." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1554753474788361.
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Akuta, Godwin Chukwuemeka. "Prevalence of refractive errors among primary school children (7-14 years) in Motherwell Township, Eastern Cape, South Africa." Thesis, University of Limpopo, 2015. http://hdl.handle.net/10386/1751.
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Thesis (MPH.) --University of Limpopo, 2015<br>Background: Uncorrected refractive errors remain a public health problem among different population and age groups worldwide, including South Africa. Refractive error has serious visual and functional impacts on those affected. In children, refractive errors may negatively affect the academic pursuits and activities of daily living such as reading.
Aims and Objectives: To determine and document the prevalence, types and magnitude together with age and gender differences of refractive errors among primary school children in Motherwell Township, Eastern Cape Province, South Africa.
Methods: This was a quantitative, cross sectional refractive error study. Four hundred and twenty one (421) school children aged 7 – 14 years were randomly selected from five randomly selected schools in Motherwell Township, Eastern Cape Province, South Africa. Visual examination which included unaided and aided visual acuity (with LogMAR E chart), non-cycloplegic autorefraction, subjective refraction, internal and external examination of the eye using an ophthalmoscope was conducted. Refractive errors were measured with an autorefractor, refined subjectively and findings presented in spherical form. Hyperopia was defined as a spherical equivalent (SE) of +0.50 D or greater, myopia as spherical equivalent of -0.50 D or greater. A cylindrical power of -0.50 DC (D cylinder) or greater was considered as astigmatism.
Results: The prevalence of hyperopia, myopia and astigmatism among the children were 25.2%, 18.7% and 58.0% respectively. Hyperopia ranged from +0.50 to +3.62 D and myopia ranged from -0.50 D to -20.25 D in the right eyes with a mean of -0.17 ± 1.7 D. In the left eye, hyperopia ranged from +0.50 to +2.62 D and myopia ranged from -0.50 to -20.62 D with a mean of -0.12 ± 1.7 D. Astigmatism in the right eyes ranged from -0.50 to -5.50 D with a mean of -0.6 ± 0.52 D and in the left eye ranged from -0.50 to -4.00 D with a mean of -0.6 ± 0.45 D respectively. Association between hyperopia and age was not statistically significant (p = 0.839), also refractive error and gender was statistically insignificant (p = 0.120). Against-the-rule (ATRA) astigmatism (43.4%) was more common, followed by with-the-rule (WTRA) astigmatism (39.0%) and oblique, (all other meridians) (17.6%). There was a significant association between types of astigmatism and age (p = 0.05), more so inter-gender difference in the prevalence of different types of astigmatism was not statistically significant (p = 0.774).
Conclusion: The study concludes that refractive error has high prevalence of 43.9% in this children population. Astigmatism (58.0%) was more common followed by hyperopia (25.2%)
v
and myopia (18.7%). Although hyperopia was not age dependent, there was obvious relationship pattern between female genders and hyperopia in the present study. Population-based vision screening or at least school visual screening in the rural communities of Motherwell Township is, therefore recommended. Vision screening and proper eye examination with appropriate optical compensation will improve the activity of daily living and quality of life of those affected.
Key words: Refractive error, hyperopia, myopia, astigmatism, school children
33
Abraham, Opare. "School Vision Screening Programs In Reducingchildren With Uncorrected Refractive Error In Low And Middle-income Countries (Lmic)(Systematic Review)." Master's thesis, Faculty of Health Sciences, 2019. http://hdl.handle.net/11427/31171.
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Background: The prevalence of uncorrected refractive error among school-age children is on the rise with a detrimental effect on academic performance and socio-economic status of those affected. School vision screening appears to be an effective way of identifying children with uncorrected refractive error so early intervention can be made. Despite the increasing popularity of school vision screening programs in recent times, there is a lot of debate on its effectiveness in reducing the proportion of children with uncorrected refractive error in the long term especially in settings where resources are limited. Objective: To assess the effectiveness of school vision screening programs in reducing children with uncorrected refractive error in LMIC. Search Methods: To identify studies suitable for this systematic review, a comprehensive and systematic search strategy was employed. We searched various databases and the search was restricted to articles published in English. We included RCTs, cross-sectional studies, case-control studies, and cohort studies. Participants included school children who had undergone vision screening as part of school vision screening programs in the LMIC setting and found to have a refractive error. Two independent reviewers screened the result of the search output and performed a full-text review of the search result to identify papers that met the pre-defined inclusion criteria. Data extraction and risk of bias assessment for the included studies was performed by the two independent reviewers and discrepancies were resolved by consensus and through consultation. The certainty of the evidence was assessed using the GRADE approach. Main Result: We found thirty relevant studies conducted in ten different countries that answered our review questions. Our review showed that school vision screening may be effective in reducing the proportion of children with an uncorrected refractive error by 81% (95% CI: 77%; 84%, moderate certainty evidence), 24% (95% CI: 13%; 35%, moderate certainty evidence,) and 20% (95% CI: 18%; 22%, moderate certainty evidence) at two, six, and more than six months respectively after its introduction. Our review also suggest that school vision screening may be effective in achieving 54% (95% CI: 25%; 100%, moderate certainty evidence), 57% (95% CI:46%; 70%, low certainty evidence), 38% (95% CI: 29%; 51%, moderate certainty evidence) and 41% (95% CI: 24%; 68%, low certainty evidence) level of spectacle wear compliance among school children at less than three months, at three months, at six months and at more than six months respectively after its introduction. Our review further found moderate to high certainty evidence indicating that school vision screening together with the provision of spectacles may be relatively cost-effective, safe and has a positive impact on the academic performance of children. Conclusion: Result of this review shows that school vision screening together with the provision of spectacle may be a safe and cost-effective way of reducing the proportion of children with uncorrected refractive error with a long-term positive impact on academic performance of children. Most of the studies included in this review were however conducted in Asia and the applicability of this finding to countries in other regions especially those outside the LMIC circle is not clear.
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Yoshikawa, Munemitsu. "Comprehensive Replication of the Relationship Between Myopia-Related Genes and Refractive Errors in a Large Japanese Cohort." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225503.
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Yi, Fan, and n/a. "Optimal Algorithmic Techniques of LASIK Procedures." Griffith University. School of Engineering, 2006. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20070216.152339.
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Clinical wavefront-guided corneal ablation has been now the most technologically advanced method to reduce the dependence of glasses and contact lenses. It has the potential not only to eliminate spherocylindrical errors but also to reduce higher-order aberrations (HOA). Recent statistics show that more than 96% of the patients who received laser in situ keratomileusis (LASIK) treatment reported their satisfaction about the improvement on vision, six months after the surgery. However, there are still patients complaining that their vision performance did not achieve the expectation or was even worse than before surgery. The reasons causing the unexpected post-surgical outcome include undercorrection, overcorrection, induced HOA, and other postoperative diseases, most of which are caused by inaccurate ablation besides other pathological factors. Therefore, to find out the method to optimize the LASIK procedures and provide a higher surgical precision has become increasingly important. A proper method to calculate ablation profile and an effective way to control the laser beam size and shape are key aspects in this research to resolve the problem. Here in this Master of Philosophy degree thesis, the author has performed a meticulous study on the existing methods of ablation profile calculation and investigated the efficiency of wavefront only ablation by a computer simulation applying real patient data. Finally, the concept of a refractive surgery system with dynamical beam shaping function is sketched, which can theoretically overcome the disadvantages of traditional procedures with a finite laser beam size.
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Hassert, Jennifer C. "Gaining Focus: Using RNAi during Lens Development to Understand Emmetropization Mechanisms Found within the Diving Beetle Larvae Thermonectus Marmoratus." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin156387276836344.
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Yi, Fan. "Optimal Algorithmic Techniques of LASIK Procedures." Thesis, Griffith University, 2006. http://hdl.handle.net/10072/368097.
Texto completoResumen
Clinical wavefront-guided corneal ablation has been now the most technologically advanced method to reduce the dependence of glasses and contact lenses. It has the potential not only to eliminate spherocylindrical errors but also to reduce higher-order aberrations (HOA). Recent statistics show that more than 96% of the patients who received laser in situ keratomileusis (LASIK) treatment reported their satisfaction about the improvement on vision, six months after the surgery. However, there are still patients complaining that their vision performance did not achieve the expectation or was even worse than before surgery. The reasons causing the unexpected post-surgical outcome include undercorrection, overcorrection, induced HOA, and other postoperative diseases, most of which are caused by inaccurate ablation besides other pathological factors. Therefore, to find out the method to optimize the LASIK procedures and provide a higher surgical precision has become increasingly important. A proper method to calculate ablation profile and an effective way to control the laser beam size and shape are key aspects in this research to resolve the problem. Here in this Master of Philosophy degree thesis, the author has performed a meticulous study on the existing methods of ablation profile calculation and investigated the efficiency of wavefront only ablation by a computer simulation applying real patient data. Finally, the concept of a refractive surgery system with dynamical beam shaping function is sketched, which can theoretically overcome the disadvantages of traditional procedures with a finite laser beam size.<br>Thesis (Masters)<br>Master of Philosophy (MPhil)<br>School of Engineering<br>Full Text
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Jorge, Francisco Vieira. "Avaliação do erro refrativo em cães pseudofáquicos, afáquicos e fáquicos com recurso a retinoscopia de luz em fenda." Master's thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2017. http://hdl.handle.net/10400.5/14335.
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Dissertação de Mestrado Integrado em Medicina Veterinária<br>A ametropia é uma das causas de diminuição da acuidade visual, podendo comprometer grandemente a visão de um cão. Neste estudo pretende-se avaliar o erro refrativo em cães submetidos a cirurgia de cataratas por facoemulsificação com implante de lente intraocular, a eficácia do poder dióptrico usado das lentes intraoculares usadas atualmente, estabelecer uma correlação entre cães microftálmicos e os seus valores refrativos e em paralelo avaliar o estado refrativo de uma população de cães saudáveis que constituem o grupo controlo.
Uma população de 53 cães, perfazendo um total de 99 retinoscopias, foi dividida em 3 grupos: pseudofáquicos (n=43 olhos), afáquicos (n=4 olhos) e fáquicos (n=52) correspondendo ao grupo controlo. As retinoscopias foram feitas através da refração dos meridianos vertical e horizontal; os meridianos oblíquos apenas foram avaliados na presença de reflexos em tesoura. Não foram usados quaisquer fármacos cicloplégicos.
O estado refrativo médio foi de +3.74 +/-5.45D (-3.5; +21D) no grupo dos pseudofáquicos; +16.94 +/-1.39D (+15.5;+18.25D) nos afáquicos e -0.03 +/-1.64D (-5.0;+4D) nos fáquicos. No grupo dos pseudofáquicos 72.2% apresentaram hipermetropia e 13.8% miopia e emetropia. Foi diagnosticado astigmatismo em 3 olhos. Observou-se anisometropia em 10 cães (1;20.5D) e antimetropia em dois. A correlação entre o valor refratado e o comprimento axial sugere uma tendência para a emetropia em animais com diâmetro ocular superior (P= 0.0845; rho=-0.3). No grupo fáquico, 44% apresentaram-se emétropes, 30% hipermétropes e 26% míopes. A hipermetropia baixa foi predominante nos cães hipermétropes (66.7%). Não foram observados casos de astigmatismo ou anisometropia. Foi encontrada uma relação entre o estado refrativo e o tamanho da raça no grupo fáquico (P=0.002). A análise de correlação entre o valor refratado e a idade dos cães sugere a tendência para a miopia ou diminuição de valores de hipermetropia em cães mais velhos (P = 0.054; rho = -0.273).
As raças médias demonstraram estar mais próximas da emetropia quando comparadas com raças grandes e pequenas (P=0.002). No grupo operado, as raças grandes estavam mais adaptadas a IOLs de 41D, enquanto as raças médias e pequenas apresentaram grande variabilidade no estado refrativo. Os cães microftálmicos operados apresentaram alta hipermetropia. Mais estudos devem ser conduzidos para relacionar caraterísticas biométricas individuais com o poder dióptrico necessário, levando assim a uma oferta mais alargada de IOLs em cães.<br>ABSTRACT - Ametropia is a possible cause for diminished visual acuity in dogs and may lead to a severe compromise of their vision. In this study under this master thesis, we aimed to evaluate the refractive error in dogs with IOL implants, the efficacy of the dioptric power used in nowadays IOL implants, attempt to establish a correlation between microphthalmic dogs and refractive values and in parallel to evaluate the refractive state on a healthy control population of dogs.
A population of 53 dogs, corresponding to a total of 99 retinoscopies, was divided in 3 groups: pseudophakic (n=43 eyes), aphakic (n=4 eyes) and a phakic healthy control group (n=52 eyes). Streak retinoscopy was performed by horizontal and vertical refraction. Oblique meridians were refracted only when swirling or scissor like reflexes were observed. No cycloplegic drugs were administered.
Mean refractive state in the different groups corresponded to: pseudophakics +3.74 +/-5.45D (-3.5; +21D); aphakics +16.94 +/-1.39D (+15.5;+18.25D) and phakic group -0.03 +/-1.64D (-5.0;+4D). On the pseudophakic group 72.2% were hyperopic, 13.8% myopic and emmetrope. Astigmatism was diagnosed in 3 eyes. Anisometropia was observed in 10 patients (1; 20.5D) and antimetropia in 2. Correlation between refractive values and optic axial length suggested a tendency towards emmetropia in animals with higher ocular diameter (P= 0.0845; rho=-0.3). On the phakic group 44% were emmetrope, 30% hyperopic and 26% myopic. Low hyperopia predominated on hyperopic eyes (66.7%). No cases of astigmatism or anisometropia were registered. An association between refractive state and animal size was found in phakic dogs (P=0.002). Correlation analysis between retinoscopy values and age suggested a tendency towards lower hyperopic values or myopia in older animals (P = 0.054; rho = -0.273).
Medium size breeds were closer to emmetropia than small/ large breeds (P=0.002). On the operated group larger breeds were more adapted to 41D IOLs, small/medium size breeds presenting higher variability in refractive state. Microphthalmic operated patients showed high hyperopia.
More studies should be conducted to correlate individual biometric characteristics with needed diopter strength, leading to a wider range of available IOLs in dogs.<br>N/A
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Kuchem, Mallory Kuhlmann. "Ciliary muscle, eye shape, and accommodation in adults with anisometropia." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338254685.
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Nava, Diane Rachel. "Participation of retinal glucagonergic amacrine cells in the regulation of eye growth and refractive error| Evidence from neurotoxins and in vivo immunolesioning." Thesis, University of California, Berkeley, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10150995.
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<p> Growth is one of the fundamental characteristics of biological systems. The study of eye growth regulation presents an interesting window that allows for the investigation of the role of the visual environment on internal processes. We now know that there is an intricate circuitry within the eye, independent of higher brain processes, that controls the growth of the eye but more needs to be elucidated about these local regulatory circuits. An improved understanding of this circuitry is critical to developing new therapies for abnormalities in eye growth regulation such as myopia, which is impacting more and more individuals around the world each day and in its more severe from, is linked to potentially blinding ocular complications. </p><p> The role of retinal glucagon, a neuropeptide, in the regulation of eye growth and refractive error has attracted the interest of researchers over the past 15 years yet there remain many unresolved questions. The research described in this dissertation aimed to elucidate the respective roles in eye growth regulation of specific subpopulations of retinal glucagonergic amacrine cells, which have been the subject of much speculation as the source of inhibitory growth signals, i.e. stop signals, yet not thoroughly investigated. </p><p> The approach taken to investigate this problem is to ablate glucagonergic amacrine cells in vivo using different neurotoxins, and to examine how this affects the sign-dependent circuitry of eye growth regulation. In addition, with the advent of advancements in high resolution imaging and electrophysiology, we were able to characterize the effects of these neurotoxins on the region-specific and time-sensitive changes in the structure and function of the living retina. </p><p> That the inhibitory response induced by imposed myopic defocus remains intact, in spite of total ablation of glucagon cells (Chapter 5) or elimination of the peripheral glucagon cells (Chapter 3) and other unintended adverse retina effects, compared to findings from previous studies involving QUIS (Chapter 2) of this thesis, is a novel finding. These results point to the same conclusion that glucagon cells themselves are not responsible for the decoding of the sign of optical defocus, but appear to have a role in fine-tuning of compensatory growth responses. The results of our experiments also suggest that the choroid may serve as an intermediate relay, and the altered anterior chamber development raise the further possibility that retina-derived growth modulatory factors also regulate the anterior segment, perhaps reaching this more remote site by diffusion forward through the vitreous chamber or via the uvea.</p>
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Miller, Karina Y. "Contact Lens, Academics and Self-Perception Study: Follow-up Results." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1586881377813119.
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Lloyd, Joshua S. "Commercialization of Software for the Prediction of Structural and Optical Consequences Resulting from Corneal Corrective Treatments." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1447778132.
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Bade, Annette. "Adaptation to Spectacle Wear in Children and Adolescents Diagnosed with Autism." Thesis, NSUWorks, 2014. https://nsuworks.nova.edu/hpd_opt_stuetd/9.
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Objectives: This study compares wearing time for four months after receiving a new spectacle correction in subjects within Autism Spectrum Disorder (ASD) population to typically developing (TD) children and adolescents age 9 to 17 years old. Methods: Children and adolescents who were ASD or TD were enrolled from subjects recruited from another pilot study focused on eye examination testing for children and adolescents with ASD. A psychologist determined group status/ eligibility using American Psychiatric Association Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition-Text Revision (DSM-IV-TR) criteria after review of previous evaluations and parent report of symptomology on the Social Communication Questionnaire. Parents provided the subject's age, level of parent education, gender, race, ethnicity and urbanization level. Parents completed a telephone survey at 1, 2, 4, 8, 12, and 16 weeks after the child received their spectacles. The survey asked questions about wearing time, willingness to wear spectacles and amount of prompting required. Data was analyzed to determine if there were differences between the ASD and TD group. Results: 22 subjects were enrolled who met review criteria for ASD or TD group and needed refractive correction. No significant difference was found between ASD and TD wearing time (p > 0.05). Age, gender, ethnicity, level of parent education, urbanization level and grade in school did not demonstrate differences in adaptation between the TD and ASD groups. Conclusions: Parental reports of wearing time and resistant behavior demonstrate that children and adolescents with ASD adapt to spectacle wear for significant refractive error similarly to typical children and adolescents.
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Naël, Virginie. "Impact des troubles visuels sur la perte d'autonomie et le déclin cognitif du sujet âgé Prevalence and associated factors of uncorrected refractive error in older adults in a population-based study in France Visual impairment, undercorrected refractive errors, and activity limitations in older adults : findings from the three-city Alienor study." Thesis, Sorbonne université, 2018. https://accesdistant.sorbonne-universite.fr/login?url=http://theses-intra.upmc.fr/modules/resources/download/theses/2018SORUS271.pdf.
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Le vieillissement de la population s’accompagne de pathologies chroniques, productrices de dépendance, dont la principale cause est le déclin cognitif et la démence, empêchant un vieillissement en bonne santé. Les troubles visuels, fréquents dans la population âgée et insuffisamment pris en charge, pourraient représenter une piste pour la prévention de ces pathologies chroniques. L’objectif principal de cette thèse était d’analyser le retentissement des troubles visuels sur la perte d’autonomie et les troubles cognitifs du sujet âgé et d’évaluer dans quelle mesure l’amélioration de la vision des personnes âgées pourrait améliorer leur état de santé. Ces travaux ont été réalisés à partir des données de 9294 participants de l’étude des Trois-Cités (3C) et de 963 participants de l’étude ophtalmologique Aliénor, nichée dans la cohorte 3C. Ces cohortes comportent des données détaillées de cognition, de dépendance et de vision. Dans notre étude, nous avons estimé que 38,8% des personnes âgées avaient des erreurs de réfraction (myopie, astigmatisme, hypermétropie) mal ou non corrigées par des lentilles ou lunettes de vue. Une dépendance plus élevée a été retrouvée à partir d’une acuité visuelle de loin inférieure à 8/10ème et près de 1/5 de la dépendance pourrait être évitée par des lentilles ou lunettes de vue adaptées. Les troubles visuels ont été associés à un risque augmenté de démence au cours de 12 ans de suivi, avec un risque plus élevé chez les personnes présentant de façon conjointe des troubles dépressifs. En revanche, aucune association longitudinale n’a été retrouvée avec le déclin cognitif. Ces travaux apportent des arguments pour justifier d'une meilleure prise en charge des troubles visuels en prévention de la dépendance ; toutefois des études complémentaires semblent nécessaires pour conforter l'impact des troubles visuels sur la démence<br>With the ageing of the population there is an increase of chronic pathologies, leading to functional limitations. Cognitive decline and dementia are the main causes of these limitations, preventing healthy ageing. Visual impairment, frequent in the elderly population and insufficiently managed, could represent a pathway for the prevention of these pathologies. The main objective of this work was to analyze the impact of visual impairment on activity limitations and cognitive impairment and to evaluate to what extent the improvement of vision could improve cognitive and functional health. This work was based on the analysis of 9294 participants from the Three City (3C) cohort and 963 participants from the Alienor ophthalmological study, nested in the 3C study. Detailed data on cognition, activity limitations and vision are available in these cohorts. In our study, we estimated that 38.8% of older adults had refractive errors (myopia, astigmatism, and hyperopia) which were poorly or not corrected by lenses or glasses. An effect of visual impairment on activity limitations has been found from a visual acuity less than 20/25 and nearly 1/5 of limitations could be avoided by best-achieved optical correction. Visual impairment was also associated with an increased risk of dementia over a 12-year follow-up period, with a higher risk in participants with both visual impairment and depressive symptoms. Nevertheless, no longitudinal associations were found with cognitive decline. This thesis provides supplementary arguments to promote a better management of visual impairment in prevention of functional limitations; however, further studies are needed to study the impact of visual impairment on cognitive decline and dementia
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Gammoh, Yazan S. S. "Refractive error, ocular biometry and oculomotor function: The prevalence of myopia and its potential risk factors in the Middle East, with an investigation of dynamic accommodation responses and axial length fluctuations in young myopic adults." Thesis, University of Bradford, 2011. http://hdl.handle.net/10454/5376.
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The main experimental work of this thesis has been a cross-sectional study of the prevalence of refractive error and its biometric correlates in Middle Eastern adults. In addition dynamic accommodative responses and twenty-four hour axial length fluctuations were investigated in young myopic adults.
The prevalence of myopia in 3000 Middle Eastern adults (age range 17-40 years) was similar to previously reported levels of myopia in the West. Myopia was associated with a higher level of education, occupations with a high nearwork demand and positive family history of myopia; all of which have been identified as risk factors for myopia development and progression
Diurnal variations in axial length (AL) of similar magnitude to those previously reported in emmetropes were observed in myopes recruited in the current thesis. However, the pattern of the diurnal variation in AL was significantly different between early-onset myopes (EOMs) and late-onset myopes (LOMs).
There were no significant differences between EOMs and LOMs in the dynamic accommodative response to a sinusoidally oscillating target. The accommodative phase lag was increased following 30 minute adaptation to myopic defocus using +2.00 D lens. However, intense prolonged (30 minute) nearwork was found to have no effect on accommodative gain or phase lag.
A number of recommendations for further work on the prevalence of refractive error in the Middle East are suggested along with further research on diurnal AL variations and dynamic accommodative responses in EOMs and LOMs.
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Hookway, Larry Allen. "Assessment of Patient Satisfaction and Willingness to Pay for Ready-Made Bifocals and Reading Spectacles in a 35 Years or Older Clinic Population in Granada, Nicaragua." Thesis, NSUWorks, 2011. https://nsuworks.nova.edu/hpd_opt_stuetd/2.
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Background: The World Health Organization estimates that there are 517 million people in the world who are visually impaired due to uncorrected presbyopia. Equal sphere ready-made bifocal and single vision reading spectacles are an inexpensive alternative to custom made spectacles. Methods: A visual satisfaction questionnaire was administered before patients were examined at an outreach clinic and again after ready-made bifocals or reading spectacles were dispensed. The results of both sets of questions along with presenting acuities, corrected acuities, refractive data, and willingness to pay were analyzed. Results: There was an unmet need of 38% (of the 338 subjects that needed glasses only 208 had them). There was no gender bias; the unmet need was higher in the rural areas (47% rural, 36% urban). Those who could not read were 3.4 times less likely to have the glasses they needed than the literate. Unmet need decreased with every level of education. Those without any schooling showed 77% prevalence of unmet need and those with university education had an unmet need rate of 32%. Ready-made spectacles were dispensed to 89.5% of those examined. The ready-made bifocals were very well accepted, with the percentage of subjects giving the highest satisfaction rating improving from a presenting value of 11% to 89.4% with the bifocals at distance and from 6.6% to 89.4% at near. Distance visual acuity of 20/40 or better improved from the presenting value of 60% to 84.5% and near vision of 20/40 or better improved from the presenting value of 44% to 97%. With ready-made single vision readers, functionally good near vision (20/40 or better) improved from a presenting value of 38% to 97%. The highest ranking for near satisfaction improved from 6.3% to 86.6%. The subjects indicted that they would be willing to pay US$18.39 to replace the bifocals and US$16.67 to replace the readers. Conclusion: There is a high unmet need for vision correction in the population over age 35 in Nicaragua. Dissatisfaction with distance and near vision is very high. Although custom made glasses are ideal, ready-made bifocals and ready-made single vision readers are an acceptable and affordable alternative.
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Hoseini, Yazdi Seyed Hosein. "Spatial characteristics of the response of the human choroid to imposed defocus." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/120362/1/Seyed%20Hosein_Hoseini%20Yazdi_Thesis.pdf.
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This thesis examined the thickness of the human choroid across a substantially larger region (~55°) than previously examined (~17°), its regional variation associated with myopia, and its short-term response to different spatial patterns of optical defocus. This research provided the first evidence of a local response of the choroid to a region specific pattern of myopic defocus in the human eye. These findings add to the current understanding of the choroid's contribution to vision dependent mechanisms of human eye growth and may assist in optimising the optical design of myopia control interventions.
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Gammoh, Yazan Sultan Sa¿ad. "Refractive error, ocular biometry and oculomotor function : the prevalence of myopia and its potential risk factors in the Middle East, with an investigation of dynamic accommodation responses and axial length fluctuations in young myopic adults." Thesis, University of Bradford, 2011. http://hdl.handle.net/10454/5376.
Texto completoResumen
The main experimental work of this thesis has been a cross-sectional study of the prevalence of refractive error and its biometric correlates in Middle Eastern adults. In addition dynamic accommodative responses and twenty-four hour axial length fluctuations were investigated in young myopic adults. The prevalence of myopia in 3000 Middle Eastern adults (age range 17-40 years) was similar to previously reported levels of myopia in the West. Myopia was associated with a higher level of education, occupations with a high nearwork demand and positive family history of myopia; all of which have been identified as risk factors for myopia development and progression Diurnal variations in axial length (AL) of similar magnitude to those previously reported in emmetropes were observed in myopes recruited in the current thesis. However, the pattern of the diurnal variation in AL was significantly different between early-onset myopes (EOMs) and late-onset myopes (LOMs). There were no significant differences between EOMs and LOMs in the dynamic accommodative response to a sinusoidally oscillating target. The accommodative phase lag was increased following 30 minute adaptation to myopic defocus using +2.00 D lens. However, intense prolonged (30 minute) nearwork was found to have no effect on accommodative gain or phase lag. A number of recommendations for further work on the prevalence of refractive error in the Middle East are suggested along with further research on diurnal AL variations and dynamic accommodative responses in EOMs and LOMs.
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Greiner, Katie Lynn. "Quality of Life of Pediatric Bifocal Soft Contact Lens Wearers." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243463393.
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Guisasola, Valencia Laura. "Distribució de l'impediment visual a la població adulta de Catalunya." Doctoral thesis, Universitat Pompeu Fabra, 2014. http://hdl.handle.net/10803/286788.
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La visió és considerada un important indicador de salut i qualitat de vida tant de les persones
com de les comunitats. El coneixement de les xifres de distribució de l’impediment visual
poblacional, esdevé una eina de planificació imprescindible per l’elaboració de polítiques
públiques de salut.
L’objectiu principal de l’estudi, és pal·liar la situació de buit de dades referents a l’impediment
visual a Catalunya i millorar l’efectivitat de la seva recol·lecció, per orientar la planificació de
polítiques públiques i els protocols de les societats de prevenció de riscos laborals.
Aquest estudi conclou en 4 principals resultats: a) proporciona per primera vegada, dades de
l’impediment visual en adults a Catalunya que indiquen majors prevalences entre les dones, la
gent gran i els col·lectius de pitjor posició socioeconòmica; b) introdueix noves preguntes de
visió, conferint a l’Enquesta de Salut Catalunya la capacitat d’orientar la planificació de
polítiques de salut; c) determina que en una població laboral, l’error refractiu corregit es
concentra majoritàriament entre les dones i els treballadors no manuals; d) conclou que la
utilització de correcció òptica és més comú entre els grups socialment més avantatjats i en
determinades ocupacions amb majors requeriments de visió.<br>Vision is considered an important indicator of the health status and quality of life of both
individuals and communities, and reliable data on the distribution of visual impairment is an
essential planning tool for the development of public health policies.
The overall aim of this study was to resolve the problem of lack of data on visual impairment in
Catalonia, and to improve the effectiveness of data collection on visual health for public policy
planning.
This study produced four main findings: a) for the first time, it provides data on visual
impairment in adults in Catalonia, showing a higher prevalence among women, seniors and
people of lower socioeconomic status; b) it introduces new questions on vision, giving ESCA
the capacity to influence health policy planning; c) it reveals that corrected refractive error in
the working population is concentrated mainly among women and non-manual workers; and
d) it confirms that the use of optical correction is more common among socially advantaged
groups and in certain occupations with greater vision requirements