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PubMed2006

Uncorrected refractive error in Singapore teenagers.

AIM: To study the prevalence rate of uncorrected refractive error and associated risk factors among Singapore schoolchildren aged 12-16 years (grade 7). METHODS: A cross sectional study of 628 participants (participation rate 99.8%) was conducted in two schools. An interviewer led questionnaire asking about sociodemographic variables and risk factors was administered. Refractive errors were measured using a table mounted autorefractor. Participants with habitual visual acuity (VA) of 0.2 logMAR or worse underwent subjective refraction. Uncorrected refractive error was defined as improvement of at least 0.2 logMAR in best corrected visual acuity after subjective refraction. RESULTS: The prevalence rate of uncorrected refractive error was 22.3% (95% confidence interval (CI) 19.0% to 25.5%). The multivariate adjusted odds ratio of uncorrected refractive error in students with the lowest academic ability was 2.24 (95% CI 1.34 to 3.73). Increasing time interval since the last visit to an eye care provider increased the risk of uncorrected refractive error (trend p = 0.001). CONCLUSION: Uncorrected refractive error was a significant problem among Singapore students aged 12-16 years (grade 7). Uncorrected refractive error was more common among students with low academic ability or those who had not visited an eye care provider for a long time.

Adolescent↗
PubMed2004

Refractive error in premature infants.

PURPOSE: To determine the incidence and the degree of refractive error between the ages of 2 weeks and 6 months in premature infants without retinopathy of prematurity and to seek a correlation between refractive error and age at examination, birth weight, or gestational age. SUBJECTS AND METHODS: In this observational cross-sectional study, eye refraction in 390 premature infants, with no ocular pathology, was measured by cycloplegic retinoscopy at the age of 2 weeks to 6 months. A correlation was sought between refractive error and perinatal variables. RESULTS: Of the 390 infants reviewed, 347 (89%) had a refractive error and 43 (11%) were emmetropic in both eyes. Most of the infants were hyperopic (76.8%). Myopia was observed in only 11.9%. Astigmatism was found in 24.4% of the infants. The mean age at examination was 2.1 +/- 1 months; the mean birth weight was 1639 +/- 444 g, and the mean gestational age at birth was 32.2 +/- 2.4 weeks. The mean spherical equivalent of refraction was +1.56 +/- 1.82 diopters (D) in the right eye and +1.55 +/- 1.78 D in the left eye. Refractive error was positively correlated with age at examination ( R = 0.16, P = 0.001). The mean refractive error was +1.24 D in infants aged 1 month or less and reached +2.50 D at the age of 4 to 6 months. Refractive error was not correlated with birth weight or gestational age. CONCLUSIONS: The incidence of refractive error in premature infants without retinopathy of prematurity in the first 6 months of life may be as high as 89%. Most of these infants are hyperopic. Eye refraction is correlated with age at examination, but not with birth weight or gestational age.

Birth Weight↗
PubMed1983

Stereoscopic acuity with induced refractive errors.

The relation between refractive error and stereoscopic acuity was investigated by measuring stereoacuity with different combinations of positive and negative spherical lenses over the usual refractive correction. A detailed study was performed on two subjects. In general, there was little change in stereoacuity when the added lenses were of equal power. On the other hand, power inequality almost invariably caused a reduction in stereoacuity. A technique is described for detecting a refractive overcorrection by means of a sequence of stereoacuity measurements.

Dominance, Cerebral↗
PubMed2005

Refractive error and ocular biometry in Jordanian adults.

The aim of this study was to establish the prevalence of refractive errors in Jordanian adults of working age, and to study the ocular biometric correlates of refractive error in this population. Refractive error and ocular biometry were measured in 1093 Jordanian adult subjects aged 17-40 years to determine the prevalence of refractive error, and explore structural correlations of ametropia. Refractive error was measured using a Grand-Seiko GR-3100K closed-view infrared autorefractor. Ocular component measurements were made using A-scan ultrasonography and autokeratometry. The prevalence of myopia [spherical equivalent refraction (SER) less than -0.50 DS] and hyperopia (SER greater than +0.50 DS) was 53.71 and 5.67% respectively; 40.62% of the sample was emmetropic (refraction between +0.50 D and -0.50 D inclusive in both principal meridians). The distribution of SER was found to show marked leptokurtosis, exhibiting a peak between plano and 1 D of myopia. Corneal radius, anterior chamber depth, crystalline lens thickness, vitreous chamber depth and axial length (AL) parameters were normally distributed in the population studied. AL to corneal curvature ratio was not normally distributed, and showed marked leptokurtosis. Linear regression analysis showed that AL correlated most closely with spherical equivalent refractive error. This study has established a database of refractive error prevalence and ocular biometric correlates of ametropia in a Middle Eastern population of working age.

Adolescent↗
PubMed2003

Development of refractive error and strabismus in children with Down syndrome.

PURPOSE: To investigate the development of refractive errors and strabismus in a cohort of children with Down syndrome. METHOD: Data for 55 children with Down syndrome who are participating in this longitudinal study of visual development, first examined by us when aged less than 2 years and on at least two other occasions, were analyzed. Mohindra retinoscopy was used to measure refractive error. Ocular alignment was assessed using the Hirschberg test and, when possible, the cover test. RESULTS: Despite the high prevalence of large refractive errors in children with Down syndrome, longitudinal data showed that these are not always present in early infancy. Twenty-one (38%) of the children were emmetropic throughout the study. Of the 24 children with a significant refractive error at the outset, only 6 (25%) showed emmetropization. The others retained or increased their refractive errors. The remaining 10 children were emmetropic at the outset, but then had a significant refractive error develop. There is a high prevalence of strabismus in children with Down syndrome (29% of the total group), which cannot be attributed to the presence of hypermetropia or anisometropia. CONCLUSIONS: The retention or development of infantile refractive errors in many children with Down syndrome indicates a failure of emmetropization. All children were at risk of strabismus whatever the refractive error. The findings have implications for timing of screening programs.

Down Syndrome↗
PubMed2002

The progression of refractive error in school-age children: Shunyi district, China.

PURPOSE: To assess the progression of refractive error and the incidence of myopia in school-age children in the Shunyi District of Beijing, China. DESIGN: A longitudinal cohort study. METHODS: A population-based sample of 4,662 children initially examined in 1998 at ages 5 to 13 years was reexamined between September and November, 2000. Refractive error was measured under cycloplegia with autorefraction. Age, sex, and baseline refractive error were evaluated as risk factors for progression. RESULTS: In 28.5 months, the average change in refractive error was -0.42 diopters (standard deviation, 0.68) in right eyes. Myopic shift of refractive error was associated with female sex, older age, and higher myopic or hyperopic refractive error at baseline. The average change in astigmatic error was essentially zero, with significant change in both directions more likely among those with higher baseline astigmatism. Findings were similar for left eyes. The cumulative incidence of myopia, defined as a spherical equivalent refractive error of -0.50 diopters or more in either eye, among initial emmetropes and hyperopes was 14.1% (95% confidence interval [CI], 11.8%-16.5%) for male and 23.5% (95% CI, 20.8%-26.1%) for female subjects. Myopia incidence increased sixfold to sevenfold between baseline age 5 and 12, before decreasing at age 13, for both male and female subjects. CONCLUSIONS: In the design of cost-effective programs for the periodic screening and treatment of uncorrected refractive error, children initially found to require refractive correction should be targeted for relatively frequent rescreening, as should girls and older children. Further study is required to better understand environmental and genetic risk factors for myopia development and progression.

Adolescent↗
PubMed2004

Refractive errors in medical students in Singapore.

INTRODUCTION: Refractive errors are becoming more of a problem in many societies, with prevalence rates of myopia in many Asian urban countries reaching epidemic proportions. This study aims to determine the prevalence rates of various refractive errors in Singapore medical students. METHODS: 157 second year medical students (aged 19-23 years) in Singapore were examined. Refractive error measurements were determined using a stand-alone autorefractor. Additional demographical data was obtained via questionnaires filled in by the students. RESULTS: The prevalence rate of myopia in Singapore medical students was 89.8 percent (Spherical equivalence (SE) at least -0.50 D). Hyperopia was present in 1.3 percent (SE more than +0.50 D) of the participants and the overall astigmatism prevalence rate was 82.2 percent (Cylinder at least 0.50 D). CONCLUSION: Prevalence rates of myopia and astigmatism in second year Singapore medical students are one of the highest in the world.

Adult↗
PubMed1991

Genetics of epidermal ridges: a study in subjects with refractive errors.

The dermatoglyphic characteristics of subjects with refractive errors when compared with control group revealed significant differences in both qualitative and quantitative parameters. The loops were increased in male myopics; the whorls were increased in male hypermetropics and astigmatics and the arches were decreased in all types of refractive errors in males. However, the whorls were decreased in female hypermetropics only. The mean total ridge count was significantly higher in male astigmatics only. As regards pattern intensity (fingers) no significant difference in the mean value was observed in either sex with any type of refractive errors when compared with those of controls.

Adolescent↗
PubMed2005

Retrospective analysis of refractive errors in children with vision impairment.

PURPOSE: Emmetropization is the reduction in neonatal refractive errors that occurs after birth. Ocular disease may affect this process. We aimed to determine the relative frequency of ocular conditions causing vision impairment in the pediatric population and characterize the refractive anomalies present. We also compared the causes of vision impairment in children today to those between 1974 and 1981. METHODS: Causes of vision impairment and refractive data of 872 children attending a pediatric low-vision clinic from 1985 to 2002 were retrospectively collated. As a result of associated impairments, refractive data were not available for 59 children. An analysis was made of the causes of vision impairment, the distribution of refractive errors in children with vision impairment, and the average type of refractive error for the most commonly seen conditions. RESULTS: We found that cortical or cerebral vision impairment (CVI) was the most common condition causing vision impairment, accounting for 27.6% of cases. This was followed by albinism (10.6%), retinopathy of prematurity (ROP; 7.0%), optic atrophy (6.2%), and optic nerve hypoplasia (5.3%). Vision impairment was associated with ametropia; fewer than 25% of the children had refractive errors < or = +/-1 D. The refractive error frequency plots (for 0 to 2-, 6 to 8-, and 12 to 14-year age bands) had a Gaussian distribution indicating that the emmetropization process was abnormal. The mean spherical equivalent refractive error of the children (n = 813) was +0.78 +/- 6.00 D with 0.94 +/- 1.24 D of astigmatism and 0.92 +/- 2.15 D of anisometropia. Most conditions causing vision impairment such as albinism were associated with low amounts of hyperopia. Moderate myopia was observed in children with ROP. CONCLUSIONS: The relative frequency of ocular conditions causing vision impairment in children has changed since the 1970s. Children with vision impairment often have an associated ametropia suggesting that the emmetropization system is also impaired.

Adolescent↗
PubMed1991

Relation between spherical refractive error and visual acuity.

The relation between a spherical refractive error and visual acuity is investigated and the results compared with previous studies. This study, unlike most of the previous studies, presents a mathematical model that includes a pupil size factor. It also examines a theoretical relation between refractive error and visual acuity which predicts that there should be a linear relation among refractive error (E), the pupil diameter (D), and minimum angle of resolution (A), over a wide range of refractive errors.

Humans↗
PubMed1999

Prevalence and predictors of undercorrected refractive errors in the Victorian population.

PURPOSE: To investigate the prevalence and predictors of undercorrected refractive errors in the Victorian population. METHODS: In this prospective study, a population-based sample of residents was recruited. The improvement in visual acuity with subjective refraction was assessed. Several individual characteristics were investigated as predictors of undercorrected refractive error. RESULTS: There were 5,615 eligible residents, of which 4,735 (84%) participated in the study (53% were women). In all, 466 participants (10%) had significant undercorrected refractive error leading to an improvement of 1 or more lines of visual acuity with refraction. Age was the most important predisposing factor. The risk of undercorrected refractive error increased by 1.8 times for every decade of life starting at 40 years of age. The next most important factor was the absence of distance refractive correction. These individuals were 6.8 times more at risk compared with those who wore distance spectacles. Other significant predictors of undercorrected refractive error were the presence of cataract and European or Middle Eastern languages spoken at home. People with tertiary education or hypermetropia were less likely to need refractive error improvement. Gender, country of birth, and employment status did not have any statistically significant effect after controlling for confounders. CONCLUSIONS: The results of this study disclose people in the community who are more at risk of compromising their vision because of undercorrected refractive errors. A campaign is warranted to alert people that it may be possible to improve their vision.

Adult↗
PubMed2005

Refractive error at birth and its relation to gestational age.

PURPOSE: The refractive status of premature infants is not well studied. This study was done to find the norms of refractive error in newborns at different gestational ages. METHODS: One thousand two hundred three (1203) eyes were examined for refractive error by streak retinoscopy within the first week of life between June 2001 and September 2002. Tropicamide eye drops (0.8%) with phenylephrine 0.5% were used to achieve cycloplegia and mydriasis. The refractive error was measured in the vertical and horizontal meridia in both eyes and was recorded to the nearest dioptre (D). The neonates were grouped in five gestational age groups ranging from 24 weeks to 43 weeks. RESULTS: Extremely preterm babies were found to be myopic with a mean MSE (mean spherical equivalent) of -4.86 D. The MSE was found to progressively decrease (become less myopic) with increasing gestation and was +2.4 D at term. Astigmatism of more than 1 D spherical equivalent was seen in 67.8% of the eyes examined. Among newborns with > 1 D of astigmatism, the astigmatism was with-the-rule (vertical meridian having greater refractive power than horizontal) in 85% and against-the-rule in 15%. Anisometropia of more than 1 D spherical equivalent was seen in 31% babies. CONCLUSIONS: Term babies are known to be hypermetropic, and preterm babies with retinopathy of prematurity (ROP) are known to have myopia. This study provides data on the mean spherical equivalent, the degree of astigmatism, and incidence of anisometropia at different gestational ages. This is the largest study in world literature looking at refractive errors at birth against gestational age. It should help understand the norms of refractive errors in preterm babies.

Age Distribution↗
PubMed1997

Refractive errors in young children with Down syndrome.

Significant refractive errors are common among older children and adults with Down syndrome. We examined infants and children with Down syndrome to determine the prevalence of these errors at younger ages. Noncycloplegic retinoscopy was used to determine the refractive state of 92 infants and children with Down syndrome, aged 4 months to 12 years. The results for infants show a similar distribution of refractive errors in patients with Down syndrome and an age-matched control group. However, rather than a narrower distribution for the older age groups, as is the case with the controls, the distribution is wider, and the prevalence of refractive errors (including astigmatism) is higher among young children with Down syndrome than among controls. This high prevalence of refractive defects cannot be explained by the presence of strabismus or other pathologies.

Child↗
PubMed2004

Long-term changes in visual acuity and refractive error in amblyopes.

PURPOSE: To report long-term changes in visual acuity and refractive error for strabismic, anisometropic, and isoametropic amblyopes. METHODS: Records of patients with strabismic amblyopia, anisometropic amblyopia, and isoametropic amblyopia who were treated from 1983 to 1993 were reviewed. Excluded were patients having ocular or neurological diseases, developmental delay, and follow-up <4 years after treatment cessation. Data included best-correctable visual acuity and spherical equivalent refractive error of the amblyopic and the nonamblyopic eye at pretreatment, posttreatment, and long-term follow-up. RESULTS: Records for 61 patients met the inclusion criteria. For strabismic amblyopia (n = 22), mean visual acuity in amblyopic and nonamblyopic eyes improved 0.36 and 0.05 logarithm of the minimum angle of resolution (logMAR) units after a mean treatment time of 1 year. At long-term follow-up (mean = 9.3 years after treatment), visual acuity in the amblyopic eye regressed 0.09 logMAR and visual acuity in the nonamblyopic eye improved 0.10 logMAR units. For anisometropic amblyopia (n = 26), mean visual acuity in amblyopic and nonamblyopic eyes improved 0.30 and 0.02 logMAR units, respectively, after a mean treatment period of 1.1 year. At the long-term follow-up visit (mean = 7.1 years after treatment), visual acuity in the amblyopic eye regressed 0.09 logMAR unit and in the nonamblyopic eye improved 0.03 logMAR unit. Repeated-measures analysis of variance showed no significant effect of type of amblyopia on visual acuity of the amblyopic eye and a significant effect of visit due to treatment but not regression. The changes in visual acuity in the nonamblyopic eye from the pretreatment to the follow-up visit were significant and interacted with type, the changes being larger in strabismic amblyopia. For strabismic amblyopia, the mean refractive error in amblyopic and nonamblyopic eyes changed from +2.15 D and +1.85 D, respectively, initially to +0.45 D and +0.58 D, respectively, at the follow-up visit. For anisometropic amblyopia, the mean refractive error in amblyopic and nonamblyopic eyes changed from +1.04 D and +0.12 D, respectively, initially to +0.23 D and -0.94 D, respectively, at the follow-up visit. The effect of visit on amblyopic and nonamblyopic refractive errors was significant. For isoametropic amblyopia (n = 13), visual acuity in both right and left eyes initially was 0.39 logMAR unit and improved to 0.14 logMAR unit in each eye after a mean follow-up of 8.9 years. Refractive error in the right and the left eyes changed from -1.22 D and -1.14 D, respectively, to -2.68 D and -2.56 D, respectively, at follow-up. These differences were all significant. CONCLUSIONS: After treatment and with long-term follow up, visual acuity regresses but not significantly in the amblyopic eye in strabismic amblyopia and anisometropic amblyopia. At the same time, visual acuity in the nonamblyopic eye improves slightly. Visual acuity also improves significantly over time in isoametropic amblyopia. The refractive error of both amblyopic and nonamblyopic eyes tends to show a myopic shift regardless of the type of amblyopia.

Adolescent↗
PubMed1980

Correlation of aphakic retinal detachment and refractive error with gender.

I analyzed the aphakic refractive errors of men and women separately in a statistical study of patients with aphakic retinal detachments. I compared the distribution of aphakic refractive errors in a population of 81 adult patients with nontraumatic aphakic retinal detachment with that of a randomly selected control population of 93 adult patients with aphakia. As a group, women who developed aphakic retinal detachments were significantly more myopic than female controls (11.41 vs 12.37 diopters of spherical equivalent; P = .004). In contrast, the refractive error in men did not differ between the aphakic retinal detachment and control groups (11.31 vs 11.68 diopters; P = .156). A significantly higher percentage of patients with bilateral (87%) aphakic retinal detachments were men (P = .017). In men other risk factors for aphakic retinal detachment, including cardiovascular disease, may overshadow the influence of axial myopia.

Adult↗
PubMed1987

Use of photoretinoscopy as a screening technique in the assessment of anisometropia and significant refractive error in infants/toddlers/children and special populations.

The presence of significant refractive error and/or anisometropia can produce an irreversible decrease in visual function if not detected and treated at an early age. The general consensus is that the earlier a problem is detected, the easier the process of remediation. The authors have examined photoretinoscopy as a means of screening infant/toddlers and/or nonverbal persons for refractive anomalies. Fifty adults and fifty infants/toddlers/children were photographed and the estimated refractive error from review of the pictures was compared to the refractive error obtained from retinoscopy. The results indicate that photoretinoscopy is an effective screening procedure for the detection of significant refractive error and is extremely sensitive to anisometropia.

Adolescent↗
PubMed2002

[Epidemiologic study of refractive errors in schoolchildren in socioeconomically deprived regions in Tunisia].

PURPOSE: This study's purpose was to estimate the prevalence of common refractive errors in schoolchildren in low socioeconomic regions in Tunisia and to assess their effect on school performance. MATERIAL AND METHODS: This was a cross-sectional study done from November 1999 to January 2000 within the context of health care screening campaigns carried out by volunteer ophthalmologists and opticians in low-end socioeconomic regions in Tunisia. The concerned population was schoolchildren living in the cities of Tunis and Tabarka (North), Kerkena (Center), and Tozeur (South). We examined a total of 708 children with a mean age of 11.9 +/-3.21 years (from 6 to 20 years) and a sex ratio of 0.84. A cycloplegic refraction examination was performed on all the children. Statistical analyses with the chi squared test and the Fisher exact test allowed us to calculate the prevalence of the refractive errors totally and separately as well as the distribution according to age, sex, and region. We also searched for a possible relation between refractive errors and academic failure. RESULTS: Among the 708 children, 57.2% [CI(95)=53.4-60] had refractive errors, of which 31.6% [CI(95)=28.2-35.2] were hyperopic, whereas 9.1% [CI(95)=7.1-11.5] were myopic. Astigmatism was found in 16.4% [CI(95)=13.7-19.3]. The prevalence of myopia was significantly higher after the age of fourteen. It increased significantly with age (P=0.0003). The prevalence of hyperopia was significantly higher between the ages of 8 and 11 (P=0.0004). Hyperopic astigmatism was significantly more frequent between 6 and 9 years of age (P=0.001). There was no significant difference regarding sex. However, the distribution of the refractive errors by region showed a significantly high level of myopia in Tunis, Kerkena, and Tozeur. This difference disappeared with increasing age. The study of the effect of these refractive errors on school performance of these children from poor areas showed a significant association between all types of refractive errors and academic failure, with an odds ratio of 2.13 for all types of refractive errors, 2.69 for hyperopia, 2.87 for myopia, and 2.73 for astigmatism. CONCLUSION: This study showed the prevalence of refractive errors in a poor population of schoolchildren and emphasized the importance of such examinations. The ability of a child to participate in the educational experience is at least partially dependent on good vision.

Adolescent↗
PubMed2002

[In kinetic perimetry high refractive errors also influence the isopter position outside the central 30 degrees].

BACKGROUND: In kinetic perimetry, refractive errors are usually only corrected within the central 30 degrees of the visual field. In this study, we determined whether refractive errors have an influence on the peripheral visual field. PATIENTS AND METHODS: The peripheral visual field was determined with and without contact lens correction always by the same examiner in 58 myopic in 30 hyperopic eyes (range of refractive errors - 25 D to + 17.25 D). If the average of an isopter position determined without contact lens was outside its 95 % confidence interval, a significant influence of the corresponding refractive error was postulated. STUDYDESIGN: Experimental, clinical study. RESULTS: In uncorrected myopias > 11 D and uncorrected hyperopias > 9 D, we observed a significant inward displacement of the I4e isopter. In uncorrected myopias > 18 D and uncorrected hyperopias > 13 D, we observed a significant inwards displacement of the I3e isopter. No influence of refractive errors could be found on the V4e isopter. CONCLUSIONS: In myopias > 11 D and hyperopias > 9 D kinetic perimetry of the peripheral visual field should be performed only after correcting the refractive error with a contact lens. No refractive correction is needed if only the boundaries are determined.

Contact Lenses↗