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At least 19 recordsLinked to original sources

PubMed2000

[The history of correction of refractive errors: refractive surgery].

The evolution of particular methods of refractive surgery is presented including the origins of radial keratotomy, relaxing incisions, keartophakia, epiferatophakia and keratomileusis as well as recent adaptation of lasers for the surgical treatment of refractive error. Such famous persons as Barraquer, Sato, and Fidorov are discussed in particular. The history not only of great achievements but also of some of the false ideas which accompanied efforts to obtain the emmetropia is presented.

History, 20th Century↗

PubMed2007

Complex trait genetics of refractive error.

Refractive errors (myopia, hyperopia, and astigmatism) are complex heterogeneous disorders of the human eye and are ideal for genetic investigation. Moderate to severe refractive errors can predispose individuals to poor visual development, various types of glaucoma, misshapen corneal surfaces, premature cataracts, and loss of retinal integrity, which can lead to detachment. Knowledge of genetic mechanisms involved in refractive error susceptibility may allow treatment to prevent progression or to further examine gene-environment interactions. Early genetic predisposition detection for developing severe refractive errors may be useful for efficient and cost-effective screening program design. This review explores the genetic mechanisms associated with nonsyndromic refractive error development known to date.

Animals↗

PubMed1989

Age differences in peripheral refractive error.

Refractive error was measured at 0 degrees to 40 degrees temporal to fixation in 10 young adults (M age = 26 years) and 10 older adults (M age = 63 years). Older adults exhibited a greater amount of sphere (i.e., overall) error, but no more so in the periphery than in the fovea. Although age differences were small, younger adults were found to exhibit more peripheral astigmatism than the older adults. Discrepancies between obtained results and those of Millodot (1985) may be attributed to the relationship between peripheral astigmatism and presenting refractive status. Alternatively, a two-mechanism model of age-related change in lens curvature is capable of accounting for across-study outcome differences. Recommendations are made concerning optimal viewing conditions for the study of age differences in visual perceptual processes.

Adult↗

PubMed2003

Responsiveness of the National Eye Institute Refractive Error Quality of Life instrument to surgical correction of refractive error.

OBJECTIVE: Refractive error and the means by which it is corrected may impact substantially on quality of vision and health-related quality of life in ways not captured adequately by standard measures of visual acuity. The goal of this analysis was to evaluate the responsiveness of the National Eye Institute Refractive Error Quality of Life (NEI-RQL) instrument to surgical correction of refractive error. DESIGN: Prospective, multicenter cohort study. PARTICIPANTS: The NEI-RQL, a 42-item measure with 13 scales, was self-administered by 185 patients before and after undergoing surgical correction of myopic or hyperopic refractive error. Preoperative and postoperative clinical information was collected, including refractive error and corrected visual acuity. METHODS: Differences between preoperative and postoperative NEI-RQL scores were examined. Responsiveness was assessed using the standardized response mean and the responsiveness statistic. We also compared scales using relative efficiency estimates. MAIN OUTCOME MEASURES: Changes in NEI-RQL scales (clarity of vision, expectations, near vision, far vision, diurnal fluctuations, activity limitations, glare, symptoms, dependence on correction, worry, suboptimal correction, appearance, and satisfaction with correction). RESULTS: For myopes and hyperopes combined, refractive surgical correction was associated with statistically significant (P<0.05) improvements in scores for 11 of 13 scales. The largest improvements, ranging from 26 to 58 points on the 0 to 100 possible score range, were seen in expectations, activity limitations, dependence on correction, appearance, and satisfaction with correction. Separate analysis of myopes and hyperopes revealed similar effects in the 2 groups. Baseline scores were found to be predictive of change after surgery. CONCLUSIONS: The NEI-RQL is responsive to changes in vision-targeted health-related quality of life resulting from keratorefractive surgery. This instrument may prove useful for evaluating the beneficial and adverse impacts of surgical and nonsurgical methods of refractive error correction.

Adult↗

PubMed2004

Recovery of refractive error after corneal refractive therapy.

PURPOSE: To describe the regression of treatment (i.e., return toward baseline refractive error findings) after treatment with corneal refractive therapy (CRT). METHODS: After 6 to 9 months of treatment by a standardized protocol for CRT (application of high-Dk, proximity control, return zone contact lenses for overnight reduction of myopia), refractive error was measured within hours after awaking and at 8, 24, 48, and 72 hours. Comparison of regression is analyzed in four categories of achieved treatment. Logarithm of the minimum angle of resolution visual acuity regression was also measured. RESULTS: In general, refractive error returns to baseline after CRT for all measured ranges of refraction in the period of measurement of this study. CONCLUSIONS: The greater the magnitude of CRT treatment, the more rapid the recovery is to baseline refraction.

Contact Lenses↗

PubMed2001

Aggregation of refractive error and 5-year changes in refractive error among families in the Beaver Dam Eye Study.

OBJECTIVE: To examine aggregation of refraction, myopia, hyperopia, and astigmatism, as well as the 5-year change in each of these measures, among adult family members. DESIGN: Geographically defined, population-based cohort study in Beaver Dam, Wis. Participants were all 43 to 84 years of age in 1988. Family relationships among participants of the study were identified through interviews. The main outcome measures were noncycloplegic refractions. Aggregation was assessed by Pearson correlations and odds ratios (ORs) that both members of a pair were affected. RESULTS: Age-adjusted sibling correlation of refraction was 0.37 and the OR for a sibling to be myopic was 4.18, whereas the OR for being hyperopic was 2.87 (all statistically significant, P<.05). Correlations and ORs for parent-child and cousin relationships were smaller, and those for spousal relationships were not significant. Correlations and ORs for cylinder power and astigmatism were not statistically significant for most relationships considered. There were no statistically significant correlations or ORs for changes in any measure of refractive error. CONCLUSIONS: The strong aggregation of refractive error, including myopia and hyperopia, among siblings along with weaker associations among parent-child and cousin pairs and no associations among spouses suggest a potential genetic influence on refractive error. There is no such suggestion for a genetic influence on the changes in refraction or in cylinder power and astigmatism.

Adult↗

PubMed2005

Support for polygenic influences on ocular refractive error.

PURPOSE: Refractive errors, myopia, and hyperopia are common conditions requiring corrective lenses. The familial clustering of myopia has been well established. Several chromosomal regions have been linked to high myopia (12q, 17q, and 18q), to quantitative refraction among twins (3q, 4q, 8p, and 11p), and to families with moderate myopia (22q). This study examined the familial aggregation and pattern of inheritance of ocular refraction in an adult population, by using data from the Beaver Dam Eye Study. METHODS: Familial correlations were examined and segregation analysis was performed on the average refractive error measurements in the right and left eyes after adjustment for age, sex, and education. Analyses were based on 2138 individuals in 620 extended pedigrees with complete data on age, sex, education, and spherical equivalent. RESULTS: Substantial positive correlation was found between siblings (0.33), parents and offspring (0.17), and cousins (0.10) and lower correlation among avuncular pairs (0.08) after adjustment for age, sex, and years of education. The results of this segregation analysis do not support the involvement of a single major locus throughout the entire range of refractive error. However, models allowing for familial correlation, attributable in part to polygenic effects, provided a better fit to the observed data than models without a polygenic component, suggesting that several genes of modest effect may influence refractive error, possibly in conjunction with environmental factors. CONCLUSIONS: These results support the involvement of genetic factors in the etiology of refractive error and are consistent with reports of linkage to multiple regions of the genome.

Family Health↗

PubMed1985

Intraocular lens powers used in the triple procedure. Effect on visual acuity and refractive error.

The refractive results of 43 consecutive triple procedures (transplant, cataract extraction, and lens implant) performed by one surgeon were analyzed. Twenty-one out of 43 eyes achieved refractive errors within 2 diopters (D) of emmetropia. The mean refractive error was -1.79 D, and the mean corneal astigmatic error was 2.75 D. Seventy percent of the eyes achieved 20/40 or better corrected acuity. Forty-four percent had 20/80 or better uncorrected acuity. Using the average postoperative keratometry readings from other recent transplant cases and an updated A constant in the SRK regression formula would have placed 39 of 43 eyes (91%) within 2 D of emmetropia with a mean refractive error of -0.07 D. The use of recent keratometry readings in a multiple regression formula is recommended to improve refractive results with the triple procedure.

Cataract Extraction↗

PubMed1995

Cost-effective screening of schoolchildren for refractive errors.

Uncorrected refractive errors are the main cause of severely impaired vision in India. This in itself indicates that there is a shortage of basic eye care services and spectacles, and too little public awareness of the need for them. A simple method for screening schoolchildren for refractive errors is described and the results are analysed. Evaluation of the materials used and the accuracy of the screening shows that this method can be used successfully by teachers.

Adolescent↗

PubMed1990

Effects of intraocular lens position errors on postoperative refractive error.

Previous theoretical attempts to predict the refractive effects of intraocular lens (IOL) misalignment have resulted in conflicting information. Discrepancies in both the potential magnitude and direction of the refractive changes exist in the literature. This paper provides a detailed description of the mathematical framework required to achieve a valid predictive model and a quantitative analysis of the effects of IOL positional errors. The effects of misalignment are shown to influence the spherical refractive component primarily. Astigmatism related to oblique incidence is generally small. Movement of the IOL away from the retina produces myopia, while movement toward the retina produces hyperopia. It is likely that longitudinal IOL positional errors are a principal component of postoperative refractive errors. Alignment errors, on the other hand, must have generally minor effects on refraction.

Astigmatism↗

PubMed1995

A population-based survey of the prevalence of refractive error in Malawi.

Refractive errors, particularly myopia, are a common problem in industrialized countries, but the impression exists that myopia may be relatively uncommon in non-industrialized societies. We conducted a population-based survey of refractive error in two groups of Malawians: a group of rural agricultural workers (n = 510) and a group of students at an urban teachers' college (n = 534). The overall prevalence of myopia was low; 2.5% (95% confidence interval 1.3%, 3.7%) of participants had an error of -0.5 D or greater. The mean refractive error (right eye) in the urban student group was +0.52 D compared to +0.62 D among the rural agricultural workers and the excess myopia was accounted for by significant myopia (> or = -0.75 D) in a few individuals, rather than an overall shift towards myopia within the urban student group. Among the rural agricultural workers, literacy predicted refractive error (right eye), with a mean of +0.59 D in the rural literate compared to +0.67 D in the rural illiterate. These findings support the notion that myopia is uncommon in non-industrialized societies and that it is associated with increased literacy but we have not identified specific risk factors within this group to predict the occurrence of significant myopia. In settings such as Malawi, refractive services should be targeted to urban centers, where more educated populations are likely to be found.

Adolescent↗

PubMed2000

The refractive status and vision profile: a questionnaire to measure vision-related quality of life in persons with refractive error.

OBJECTIVE/BACKGROUND: To describe the Refractive Status and Vision Profile (RSVP), a questionnaire that measures self-reported vision-related health status (symptoms, functioning, expectations, concern) in persons with refractive error. DESIGN: Cross-sectional study by survey. PARTICIPANTS: The RSVP was self-administered by 550 participants with refractive error (or history of refractive surgery) recruited from five refractive surgery practices and one optometric practice. Information on refraction, uncorrected and best-corrected visual acuity, and history of refractive surgery was obtained from physicians' records. METHODS: Internal consistency, test-retest reliability, agreement with global measures of vision (criterion validity), discriminant validity, content validity, and construct validity (associations of scale scores with patient status variables) were assessed using Cronbach's alpha, Spearman rank correlations, factor analysis, and multitrait analysis. OUTCOME MEASURES: Scores on the overall RSVP scale (S) and on eight RSVP subscales (functioning, driving, concern, expectations, symptoms, glare, optical problems, problems with corrective lenses) were calculated based on 42 items. RESULTS: Cronbach's alpha was 0.92 for S and ranged from 0.70 to 0.93 for RSVP subscales, indicating good internal consistency. Satisfaction with vision was more strongly associated with S than with refractive error or with visual acuity. Individuals with more refractive error had significantly lower (worse) scores for S and for subscales concern, functioning, driving, optical problems, and glare. Scores for S and for subscales concern, functioning, optical problems, and driving remained significantly associated with satisfaction with vision after adjustment for age, gender, corrective lens type, and refractive error. CONCLUSIONS: The RSVP measures a range of visual, functional, and psychologic impacts of refractive error that are likely to be important to patients. The RSVP would be a useful tool for evaluating interventions for correction of refractive error and may be useful for assessing refractive surgery candidates in clinical practice.

Adolescent↗

PubMed2006

Is the Cardiff Acuity Test effective in detecting refractive errors in children?

PURPOSE: Refractive error is a common cause of reduced visual acuity in young children. This reduced vision should be detected as soon as possible to avoid development of squinting and educational disadvantage. The Bailey-Lovie Chart (BLC) is based on the logarithm of the minimal angle of resolution (logarithm of the minimum angle of resolution logMAR) and is widely accepted as the clinical standard for visual acuity testing. However, most young children are unable to perform this test because of its symbolic level. The Cardiff Acuity Test (CAT) overcomes these symbolic demands and is the test of choice for young children in most U.K. orthoptic departments. The purpose of this study is to determine how effective the CAT is in detecting reduced visual acuity caused by refractive error in young children. METHODS: Visual acuity of the right eye was tested without spectacles in 68 children (mean age, 74 +/- 14.6 months) with known bilateral symmetric refractive error (40 male) using the CAT and the BLC. Subjects were randomized to receive CAT or BLC first in a single assessment using a crossover design. Subjects scoring 0.2 logMAR or better were classified as having passed the test. RESULTS: The CAT correctly identified reduced vision caused by uncorrected refractive error in 25% (17) of the children compared with a detection rate of 97% (66) for the BLC using the specified pass criteria. Further analysis with an adjusted cut point for the CAT (0.0 logMAR), as used to identify abnormal vision in clinical practice, identified a detection rate of 56% (38 of the children). CONCLUSIONS: This study casts doubt on the current clinical practice used in orthoptic clinics by suggesting that assessment of visual acuity with the CAT alone will underdiagnose reduced acuity caused by refractive errors.

Child, Preschool↗

PubMed1983

Variation of the green-red ratio with refractive error.

The relationship of refractive error to green-red ratios among color normals was investigated by asking 27 subjects to match a standard yellow with a mixture of red and green primaries using a Nagel anomaloscope. Green-red ratios did not show any regular change with refractive error. Differences in refractive error, natural or induced, among color normal persons did not change the measurements of color vision with the Nagel anomaloscope.

Color Perception↗

PubMed1992

Myopia and refractive error in dogs.

The refractive error of 240 phakic dogs of various breeds was measured using streak retinoscopy and averaged (-0.27 +/- 1.41 D relative to infinity). Analysis by breed showed that the German Shepherd, Rottweiler, and Miniature Schnauzer breeds had an increased prevalence of myopia with an average refractive error of -0.86 +/- 1.31 D, -1.77 +/- 1.84 D, and -0.66 +/- 1.05 D, respectively. Myopia also was found in older dogs with marked nuclear sclerosis of the crystalline lens. Fifty-three percent of all German Shepherd dogs in a veterinary clinic population (n = 58 eyes) had a myopic refraction of greater than or equal to -0.50 D; 64% of all Rottweiler dogs (n = 28 eyes) were myopic. An in-depth investigation of German Shepherd dogs, using A-scan ultrasonography, photokeratoscopy, and streak retinoscopy, was done at Guide Dogs for the Blind (San Rafael, CA). By contrast with the results obtained in the veterinary clinic population, the overall average refractive error of guide dog German Shepherd dogs (n = 106 eyes) was +0.19 +/- 0.81 D, and only 15% of these dogs were myopic. The axial length and corneal curvature of myopic eyes did not differ significantly from nonmyopic eyes.

Animals↗

PubMed1987

Refractive errors in children.

Optical correction of refractive errors in infants and young children is indicated when the refractive errors are sufficiently large to cause unilateral or bilateral amblyopia, if they are impairing the child's ability to function normally, or if the child has accommodative strabismus. Screening for refractive errors is important and should be performed as part of the annual physical examination in all verbal children. Screening for significant refractive errors in preverbal children is more difficult; however, the red reflex test of Bruckner is useful for the detection of anisometropic refractive errors. The photorefraction test, which is an adaptation of Bruckner's red reflex test, may prove to be a useful screening device for detecting bilateral as well as unilateral refractive errors. Objective testing as well as subjective testing enables ophthalmologists to prescribe proper optical correction for refractive errors for infants and children of any age.

Adolescent↗

PubMed2005

Sensitivity of the National Eye Institute Refractive Error Quality of Life instrument to refractive surgery outcomes.

PURPOSE: To evaluate scores from the National Eye Institute Refractive Error Quality of Life instrument (NEI-RQL) relative to refractive surgery outcomes in myopic patients. SETTING: Large institutional ophthalmic practices. METHODS: Patients seeking refractive surgery (n = 59) self-administered the NEI-RQL before and 6 months after surgery; the comparison group of myopes and emmetropes (n = 72) not seeking refractive surgery also completed the NEI-RQL. Myopic patients seeking refractive surgery had bilateral, same-day laser in situ keratomileusis (LASIK) treatment. Regression analyses were conducted to compare survey scores in the LASIK treatment group before surgery with those in the myopic sample who were not seeking refractive surgery and to compare the survey scores in the post-LASIK treatment group (surgical emmetropes) to those in the naturally emmetropic group. Logistic regression was used to determine NEI-RQL subscales that were related to myopic patients seeking refractive surgery and myopic patients not seeking refractive surgery. RESULTS: Myopes seeking LASIK reported greater expectations for vision improvement (P < .0001), greater activity limitations (P < .0001), suboptimal correction (P = .04), worse appearance (P < .0001), and lower satisfaction (P < .0001) than myopes not seeking refractive surgery. Logistic regression showed that worse self-perceived appearance (odds ratio 20.71), more dissatisfaction with current correction (odds ratio 8.28), and higher expectations for "optimal" correction (odds ratio 6.41) were independently associated with myopes seeking LASIK, while better perceived "clarity of vision" (odds ratio = 0.20) was associated with myopes not seeking surgery. Overall, surgical emmetropes were similar to natural emmetropes in terms of refractive-error-specific quality of life (clarity of vision, near vision, far vision, diurnal fluctuations) and clinical measures of visual function, yet they reported significantly better appearance (P = .02) and greater satisfaction (P < .0001) than natural emmetropes. CONCLUSION: The NEI-RQL demonstrated vision-related quality-of-life differences when comparing patient samples associated with refractive surgery.

Adult↗

PubMed2002

Headaches associated with refractive errors: myth or reality?

INTRODUCTION: Headache and refractive errors are very common conditions in the general population, and those with headache often attribute their pain to a visual problem. The International Headache Society (IHS) criteria for the classification of headache includes an entity of headache associated with refractive errors (HARE), but indicates that its importance is widely overestimated. OBJECTIVES: To compare overall headache frequency and HARE frequency in healthy subjects with uncorrected or miscorrected refractive errors and a control group. METHODS: We interviewed 105 individuals with uncorrected refractive errors and a control group of 71 subjects (with properly corrected or without refractive errors) regarding their headache history. We compared the occurrence of headache and its diagnosis in both groups and assessed its relation to their habits of visual effort and type of refractive errors. RESULTS: Headache frequency was similar in both subjects and controls. Headache associated with refractive errors was the only headache type significantly more common in subjects with refractive errors than in controls (6.7% versus 0%). It was associated with hyperopia and was unrelated to visual effort or to the severity of visual error. With adequate correction, 72.5% of the subjects with headache and refractive error reported improvement in their headaches, and 38% had complete remission of headache. Regardless of the type of headache present, headache frequency was significantly reduced in these subjects (t = 2.34, P =.02). CONCLUSIONS: Headache associated with refractive errors was rarely identified in individuals with refractive errors. In those with chronic headache, proper correction of refractive errors significantly improved headache complaints and did so primarily by decreasing the frequency of headache episodes.

Adolescent↗