Screening For Refractive Errors Research Articles

Ophthalmologic abnormalities in high school students with mental retardation in Taiwan.

Visual and ocular disorders are common in mental retardation (MR), and can influence sensory-motor development and learning. This study investigated visual and ocular abnormalities in a population of high school students with MR. All students with MR in their first year at a special education high school who underwent ophthalmic examinations in December 2001 were included. Data were collected by retrospective review of hospital records and student health records. A total of 68 students with MR, including 45 males and 23 females, completed ophthalmologic examinations. Abnormal ophthalmologic findings in these 68 students (15-23 years old) included astigmatism (74.4%), myopia (53.7%), amblyopia (29.3%), exodeviation (23.5%), anisometropia (22.0%), blepharoconjunctivitis (20.6%), hyperopia (18.2%), cataract (13.2%) and suspected glaucoma (11.8%). Amblyopia was mainly attributed by refractive errors and strabismus. Myopia was less prevalent than in the general population of the same age in Taiwan, but astigmatism and anisometropia were more prevalent. More than one-third of the exodeviations were large-angle exotropia. The presence and type of cataract were highly associated with Down's syndrome. The prevalence of visual and ocular disorders in teenage and young-adult students with MR is high. Because these disorders can be detrimental to learning, early and regular ophthalmic examinations of children with MR are mandatory, with particular attention to screening for refractive error, amblyopia, strabismus and cataract and treatment of these conditions when identified.

Identification of infants with significant refractive error and strabismus in a population screening program using noncycloplegic videorefraction and orthoptic examination.

The second Cambridge Infant Vision Screening Program examined whether screening for accommodative errors by using videorefraction without cycloplegia could effectively serve as a first stage of screening for refractive errors, measured by standard cycloplegic retinoscopy. The screening also included an orthoptic examination for detection of strabismus. All infants born in the Cambridge (UK) Health District, over a 2-year period, were invited for screening. Of those 5142 (76%) with mean age 8.1 +/- 0.8 months (SD) attended and received noncycloplegic videorefraction and an orthoptic examination. All those with a focusing error or orthoptic problem, as well as a randomly selected sample of visually normal control subjects, were invited to follow-up a month later for cycloplegic retinoscopy, repeat noncycloplegic videorefraction and orthoptic examination. Of the 5142 screened, 514 had a focusing error or orthoptic problem (positives). Four hundred thirty-nine of these and 284 visually normal control subjects (negatives) attended follow-up. A refractive or orthoptic condition was confirmed in 59.0% of the positive cases, whereas infants in 96.8% of the negative cases were confirmed normal. Adjusting for the proportions of the population represented by those infants seen at follow-up, sensitivity for the screening procedure was calculated at 0.67 and specificity at 0.96. Detailed results are presented in terms of the different conditions detected at screening (far, near, and anisometropic focus and orthoptic error), distribution of greatest axes at screening, and a comparison of initial videorefraction with repeat videorefraction and cycloplegic retinoscopy. A noncycloplegic screening procedure, simpler to perform than cycloplegic screening, succeeded in detecting a large proportion of infants with significant ametropia, particularly those with significant hyperopia, which is considered to be a strabismogenic and amblyogenic risk factor.

Sensitivity and specificity of visual acuity screening for refractive errors in school children.

To examine the optimal cutoff point for the use of the visual acuity test to screen for refractive errors in schoolchildren. In a sample of schoolchildren between 7 and 9 years old, visual acuity testing was performed using modified ETDRS charts monocularly without optical aids by trained personnel. Cycloplegic autorefraction was performed in each eye. The screening efficacy of using various cutoff points for referring children for further optometric/ ophthalmic assessment was studied. Myopia was defined as a spherical equivalent of at least -0.5 D, hyperopia a spherical equivalent of at least +2.0 D, and astigmatism a cylinder of at least -1.0 D in at least one eye. The sensitivity, specificity, and predictive values were calculated using each patient as a case; a receiver operator curve was plotted. A total of 1,028 children were tested. A satisfactory sensitivity/specificity profile was obtained using a referral criterion of visual acuity worse than or equal to 0.28 logarithm of the minimum angle of resolution in at least one eye. In this scenario, the sensitivity and specificity of this screening test were 72% (95% confidence interval [CI], 68 to 76) and 97% (95%CI, 95 to 98), respectively. The positive and negative predictive values were 96% (95%CI, 93 to 98) and 78% (95%CI, 75 to 82), respectively. The modified ETDRS visual acuity chart can be used to predict refractive errors in schoolchildren in Singapore in a sensitive and specific manner using a referral criterion of worse than or equal to 0.28 logarithm of the minimum angle of resolution.

Non-cycloplegic screening for refractive errors in children with the hand-held autorefractor Retinomax: Final results and comparison with non-cycloplegic photoscreening

AIMS. To establish the results of refractive screening of preschool children with the hand-held autorefractor Retinomax under non-cycloplegic conditions, and to compare these results with those of photoscreening. METHODS. Among 1218 children undergoing non-cycloplegic refractive screening, 302 (25%) were also refracted under cycloplegia using the same refractor and were used as controls. Our criteria for a positive screening test were based on the spherical or cylinder values and were: myopia over 3D, astigmatism = 2D, spherical or cylindrical anisometropia = 1.5D, and hyperopia = 1.5D. Absolute myopia over 3D, absolute astigmatism = 2D, absolute anisometropia = 1.5D and absolute hyperopia > 3.5D were considered as true positives. The sensitivity, specificity, and positive and negative predictive values (PPV and NPV) were calculated within the group of controls for each refractive anomaly. On the basis of Bayes' theorem, these figures were then corrected to yield the true screening results that would be expected in a population without verification and selection bias. To determine the usefulness of this screening technique, the likelihood ratios for positive test results (+LR) were also calculated. The results of this screening in terms of sensitivity, specificity and predictive values were then compared with those of photoscreening. RESULTS. The basic results of screening with the hand-held autorefractor were as follows: –ÊHyperopia: sensitivity 46%, specificity 97%, PPV 55%, NPV 96%, +LR 15; –ÊAstigmatism: sensitivity 37%, specificity 99%, PPV 69%, NPV 96%, +LR 37; –ÊAnisometropia: sensitivity 66%, specificity 93%, PPV 19%, NPV 99%, +LR 9; –ÊMyopia: sensitivity 87%, specificity 99%, PPV 33%, NPV 100%, +LR 87. The comparison with photoscreening revealed a similar performance when screening for hyperopia, but the hand-held autorefractor yielded much better figures when screening for astigmatism. In the case of myopia and anisometropia, the lack of consistent information concerning photoscreening invalidates any comparison. CONCLUSION. The hand-held autorefractor Retinomax appears to have potential as a screening device. Our experience with the non-cycloplegic screening of preschool children for refractive anomalies indicates definite usefulness and reasonable accuracy of the Retinomax for detecting myopia, astigmatism and hyperopia. The weak point of this screening technique is the diagnosis of anisometropia, with only moderate utility and poor accuracy.

Screening for refractive errors in children: accuracy of the hand held refractor Retinomax to screen for astigmatism

AIMS To assess the reliability of the hand held automated refractor Retinomax in measuring astigmatism in non-cycloplegic conditions. To assess the accuracy of Retinomax in diagnosing abnormal astigmatism in non-cycloplegic...

Comparison of the techniques of videorefraction and static retinoscopy in the measurement of refractive error in infants

Photorefraction has been suggested as a suitable method of screening for refractive error in infants. The relative performance of cycloplegic and non-cycloplegic videorefraction and cycloplegic retinoscopy was investigated on 150 infants. Under cycloplegic conditions the correlation between findings for spherical error (Rxy = 0.70) was compatible with a previous study. However, where cycloplegia was not used for videorefraction, there was poor agreement between the two techniques in the case of astigmatic error, and all types of ametropia. Interobserver repeatability was very high both for cycloplegic retinoscopy (Rxy = 0.96 spherical error, and Rxy = 0.75 astigmatic error) and for videorefraction measurements (Rxy = 0.95 horizontal meridian of photograph and Rxy = 0.85 vertical meridian). Intraobserver repeatability was also good, both for cycloplegic retinoscopy (Rxy = 0.91 spherical error and 0.82 astigmatic error) and for videorefraction with regard to spherical errors (Rxy = 0.84). Throughout the experiments videorefraction measurements of astigmatic errors proved less consistent when compared with cycloplegic retinoscopy, and to its internal reliability.

Screening Infant Vision with Paraxial Photorefraction

Early screening for refractive errors is highly desirable. Techniques for doing this must be usable with noninstructable subjects (infants), noninvasive, and relatively easy to use. Photorefraction has been used to examine infants' refractive status. However, unless cycloplegia is used, the results can be difficult to evaluate, inasmuch as the subject's plane of focus is not known. This paper describes a photorefraction system that is being used for routine screening of young infants, without cycloplegia and without using highly skilled personnel. The major innovation is the systematic presentation of attractive targets at distances that present a range of demands to accommodation. Changes in the fundal reflections, seen in the photographs taken as the infant views the different targets, can be interpreted unequivocally to identify severe myopia and hyperopia, anisometropia, heterotropia, and anisocoria. The results can also be quantified and are compared with retinoscopic refractions.

Instant photographic refractometry in children.

A simple photographic method for detection and measurement of refractive errors in children, using a specially designed camera and electronic flash unit and 'instant' (Polaroid) film, was tested on 64 children, aged 3 to 8 years, and compared with the results from retinoscopy. The refractive errors ranged from -6.5 to +6.5 D. A light reflex in the pupil was observed on the photos of all children with hyperopia greater than = 0.5 and myopia greater than = 2.0 D. A curvilinear relationship was observed (in the range -2 to -4 and +0.5 to +3 D) between the width of the light reflex in the pupil, easily measured on the photos and the degree of refractive error, determined by retinoscopy. The degree of ametropia could be estimated with reasonable accuracy (+/- 0.5 D) in the interval from -2 to -4 D and +0.5 to +3 D. The method can demonstrate the type and, to a limited extent, also the degree of refraction anomaly and may be of value in screening for refractive errors in children.

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.

Screening for refractive errors in 6-9 month old infants by photorefraction.

The method of isotropic photorefraction has been used in a trial of refractive screening of 6-9 month old infants. Data are presented on the calibration of the method against retinoscopic measurements and its reliability. In photorefractive screening of 1096 infants under cyclopentolate cycloplegia 5% were found to be hypermetropic (over +3.5 D), 4.5% myopic, and 1.3% anisometropic (over 1 D). These refractive errors were confirmed on retinoscopic follow-up (with the exception of a few anisometropes). Follow-up of controls shows that one small refractive error was missed in 52 infants. We conclude that photorefraction is a valid and practical screening technique. Longitudinal study of infants with refractive errors will assess the value of early detection, in particular for prediction and prevention of strabismus.

Screening for refractive errors, strabismus and other ocular anomalies from ages 6 months to 3 years.

There were 3,375 children between the ages of 6 months and 3 years screened for refractive errors and strabismus. In 363 children (10.7%) some kind of pathology was detected. We suggest that continued efforts should be made to lower the age of detection of defects in vision.

Screening for refractive errors at age 1 year: a pilot study.

Cycloplegic refraction of 1-year-old children is technically possible and is acceptable to mothers as a method for screening children for visual defects. The range of refractions found in a sample of 186 1-year-old children is reported. Prediction of which children are significantly at risk for squint and/or amblyopia is possible on the basis of refractions at age 1 year according to the criteria selected for an 'abnormal' refraction. Bilateral hypermetropia and/or astigmatism or anisometropia at age 1 year was significantly (P less than 1 in 10 000) associated with a child eventually being found to have squint or amblyopia. Both the age of screening and criteria of abnormality will probably need modification. +2.50 or more D hypermetropia in any one meridian of either eye at age 1 year was even more significantly (P = 0.000 000 05%) associated with squint and/or amblyopia. The possibility that meridional hypermetropia could be the basic defect in squint and amblyopia is discussed.