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Vision screening in children tested at 7, 11, and 16 years.
Distant vision screenings of a national sample of children were performed at the ages of 7, 11, and 16. Many children with normal vision at one screening showed defects at later screenings, and altogether 18% of children with normal vision at the age of 7 had defects by the time they were 16. Twelve per cent of those with normal vision at 7 and 11 had developed a visual defect by the age of 16. Apparent improvements between screenings probably resulted largely from technical difficulties inherent in testing young children. The results clearly indicate the importance of regular vision screening during the school years and the need for comprehensive but flexible back-up services.
Assessment of the Queensland School Health Service vision screening programme.
Despite the widespread acceptance of vision screening programmes as a means of detecting ocular disorders in children, there has been little formal assessment of their validity and reliability. One such screening programme is conducted in Queensland State Primary Schools by the Division of School Health Services of the State Department of Health. A group of 877 children was screened by the Service and subsequently subjected to a formal independent ophthalmological examination. A comparison of the results of these procedures revealed that the visual screen as performed by the Service was highly accurate in the determination of distant visual acuity. Detection of manifest strabismus was less satisfactory, with between 30 and 74% of sufferers being detected. There is no evidence to suggest that a more complex protocol will improve the detection of ocular disorders. Rather, a more effective implementation of the current screening procedure is required.
Vision screening of adolescents and their use of glasses.
Vision screening was performed in over 11 000 16-year-olds who were taking part in the National Child Development Study. For distance vision 75% had normal acuity, 9% a minor defect, and 16% a more severe unilateral or bilateral defect. For near vision 85% had normal vision, 8% a minor defect, and 7% a unilateral or bilateral defect. Few children (62) with normal distant vision had defects in near vision, though many more (607) had both poor distant vision and poor near vision. Vision defects were more common in girls than in boys and occurred more often in adolescents from non-manual than manual families. Athough 18% of children had been prescribed glasses for current use, a third did not have their glasses available at the examination: 27% of the children prescribed glasses had normal unaided distant visual acuity or only a minor defect, and they constituted 42% of those who were not wearing their glasses. Further investigation is needed into the criteria on which glasses are prescribed for children and into the reasons for which they are not worn.
Vision screening in a primary care setting. A missed opportunity?
To determine the effectiveness of vision screening in a primary care setting, we administered a questionnaire and a vision test to 458 patients from a general medical clinic. Subjects were referred for complete ophthalmologic evaluation if they failed the vision test or met other "high-risk" criteria based on information contained in the questionnaire. Patient-initiated requests for eye examinations were also honored. A total of 169 patients were scheduled for eye examinations, and 148 actually underwent ophthalmologic evaluation. One hundred one of those examined were referred on the basis of the study criteria. "Serious eye disease" (cataract, glaucoma, diabetic retinopathy, or age-related macular degeneration) was diagnosed in 96 (95%) of these patients. Prompt surgical intervention was recommended in 27 (27%), and medical treatment was begun in 21 (21%). Of those with serious eye disease, 59% met the criteria by failing the vision test, while 69% met the high-risk criteria determined by the questionnaire. Of the 148 subjects who received ophthalmologic evaluations, 47 requested them. Serious eye disease was diagnosed in 23 (50%) of the 47 patients. None of these individuals required immediate surgery, and medical treatment for glaucoma was begun in eight (17%). These data suggest that screening for serious eye disease in a primary care setting is an efficient mechanism to use for the identification of patients with undetected ocular disorders that require follow-up or treatment.
Comparison of the automated vision screening test to the Snellen test.
The comparison of an automatic vision screening machine using the Landolt rings and the usual Snellen Chart was carried out among 123 second grade and 149 fifth grade students in an elementary school in Jerusalem. The sensitivity of the test for a cut-off point of greater than or equal to 6/12 according to the Snellen test was 41.7% (CI = 16.5-71.4) and the specificity was 86.5% (CI 78.1-92.2) for second graders. For fifth graders the values were 50.0% (CI = 20.1-79.9) and 90.6% (CI 83.7-94.8) respectively. Diagnosis by a specialist decreased the number of 'false negatives' and confirmed the pathological cases. The automatic test was well accepted by the children. Though more time is needed for assessment using the automatic test, its advantage is that no professional staff are required.
Comparison of vision screening by lay and professional personnel.
A previously described vision screening procedure was administered to 652 elementary school children, using lay volunteers. These students were later screened by optometrists, using the Modified Clinical Technique (MCT). Using MCT as the standard, the lay screening correctly identified 90% of the children; the incorrect identifications included 28 children (4.3%) as false negatives and 36 children (5.5%) as false positives. Analysis indicates a lower cost for the combined lay and professional screening than for professional screening alone.
An audit of preschool vision screening.
An audit was carried out to clarify the dispute surrounding the vision screening test at 3.5 years. The uptake was 53.5%, sensitivity 77%, specificity 96%, and positive predictive value 50%. In particular the uptake was poor and the test needed a clear policy for the future.
Review of children referred from the school vision screening programme in Kettering during 1976-8.
The progress of 108 children who were identified by the vision screening programme in school as having defective vision (excluding those with puberty onset myopia) was reviewed. Treatment of these children resulted in improvement in visual acuity of the worst eye (two lines or better) for 16 children. Eighteen children had severe amblyopia (6/24 or worse). Among these the vision of only five was improved by treatment. Two thirds of the children had refractive errors in the better eye which required correction. It seems sensible to identify and treat children with bilateral refractive errors, but the need to treat children with lesser degrees of amblyopia is questioned.
Stereopsis testing to reduce overreferral in preschool vision screening.
Three- and 4-year-old children who obtain the minimum failing visual acuity result of one-line difference between eyes in preschool vision screening with isolated optotypes have a high rate of overreferral. We evaluated the Random Dot E Stereotest (RDES) to determine if a passing result at a high threshold on this test, as administered by lay screeners, could safely nullify referral for a minimum failing visual acuity test result. Fifty-eight children with a "one-line difference" result also had the RDES administered to them during screening at distances of 40 cm and 1.5 m. Upon subsequent ophthalmologic examination, 45 of these children were found to be normal, and 13 had abnormal findings. Thirty-nine of the children with normal examinations had correctly passed the RDES at 1.5 m. Seven of the 13 children with abnormal findings had correctly failed the RDES. Thus, the specificity of stereotesting was 87% and the sensitivity was 54%. Among the six children who falsely passed the stereopsis test during screening, best-corrected visual acuity was no worse than 20/40 and no child had greater than a one-line difference in acuity. Therefore, no amblyopia was missed. If a passing result on the stereotest at 1.5 m had been allowed to nullify a one-line difference referral, overreferral would have decreased 87% but underreferral would have increased 46%. We cannot yet recommend modifying current visual acuity referral criteria based on stereopsis testing results until the sensitivity of stereopsis screening by lay screeners at a sufficient threshold is improved.
The Tokyo Metropolitan Home Vision Screening Program for amblyopia in 3-year-old children.
In August 1989, the Tokyo Metropolitan Government officially began a vision screening program for children aged 3 years 1 month. A 1988 pilot study of 1,303 children this age disclosed five cases (0.38%) of amblyopia. The home vision test, which uses picture cards of familiar figures, proved to be an efficient and inexpensive method of screening when incorporated into the existing health-check program for 3-year-old children. In the initial eight months of the program, 21,906 children were screened. Of these, 419 children (1.9%) were referred to an ophthalmologist for follow-up, and amblyopia was detected in 41 children (0.19%).
Vision screening of children: a review of methods and personnel involved within the UK.
The validity of vision screening of children for amblyopia, squint and significant degrees of ametropia is reviewed. The suitability of the tests used in screening, the age at which they are applied and the personnel involved is assessed. Some suggestions for improvement are made with particular reference to the optometrist's role, especially in view of the proposed child health surveillance scheme to be undertaken by selected general medical practitioners.
Vision screening in preschool children: comparison of orthoptists and clinical medical officers as primary screeners.
OBJECTIVE: To see if there were differences in referral rates and abnormalities detected from two areas that were operating different preschool vision screening programmes. DESIGN: Cohort study using case notes of referrals. SETTING: Community based secondary referral centres in the county of Avon. PATIENTS: 263 referrals from a child population of 7105 in Southmead district, an area that used orthoptists as primary vision screeners; 111 referrals from a child population of 2977 in Weston-super-Mare, an area that used clinical medical officers for screening. MAIN OUTCOME MEASURES: Amblyopia and squint detection rates, together with false positive referral rates. RESULTS: The amblyopia detection rate in Southmead district was significantly higher than in Weston-super-Mare (11/1000 children v 5/1000), as was the detection rate of squint (11/1000 v 3/1000). However, the false positive referral rate from Southmead was significantly lower than that from Weston-super-Mare (9/1000 v 23/1000). CONCLUSION: Preschool vision screening using orthoptists as primary screeners offers a more effective method of detecting visual abnormalities than using clinical medical officers.
The Davidson and Hemmendinger color rule as a color vision screening test.
The Davidson and Hemmendinger (DH) color rule was evaluated for color vision screening of normal and congenital color-defective subjects. Ninety-eight normal and 14 color-defective subjects were tested on the color rule under Macbeth illumination of 5,400 K. The color-defective subjects were also tested on the Nagel anomaloscope, the Farnsworth D-15, and the H-R-R pseudoisochromatic plates. The DH color rule performed as accurately as the anomaloscope and was superior to the other two tests in detecting anomalous trichromats and in discriminating protanomalous subjects. The color rule also discriminated dichromats from anomalous trichromats. For severe color-defective subjects (dichromats, achromats), the color rule was more time-consuming than the other tests and discrimination was less certain. Response patterns on the DH color rule and response variability of the different classifications are reported.
Vision screening in a national sample of 11-year-old children.
This report describes the results of vision screening carried out by local health authorities on a national sample of 11-year-old schoolchildren using a standard Snellen chart. Of the 12 772 children tested, 78% had an unaided distant visual acuity of 6/6 or better in both eyes (optimal vision), 10% had a distant visual acuity of 6/9 in the worse or both eyes (near-optimal vision) and 12% had a visual acuity of 6/12 or worse in one or both eyes eyes (definite visual defect). In addition, near visual acuity was tested for 12 737 children and 5% were found to have defective near vision. Glasses had been prescribed for current use in 12% of children but a quarter of those prescribed glasses did not have them available at the time of the test. Testing revealed that 22% of children whose glasses were available had optimal or near-optimal unaided distant vision, the number increasing to 98% when retested wearing glasses. In contrast, 43% of the children who were without their glasses had optimal or near-optimal vision; 27% had a bilateral defect. Amongst the children for whom glasses had not been prescribed 4-6% had a visual defect. A higher proportion of children from non-manual family background than from manual family background had visual impairment and had been prescribed glasses, but there was no significant social class difference amongst the children with visual defects for whom no glasses had been prescribed. A defect of red/green colour vision was recorded in 6% of boys and 1% of girls. The proportion of children with poor visual acuity was similar in the group of children with defective colour vision and the group with normal colour vision.
Comparison of vision screening performed by optometrists and nurses.
The rates of patient referral by optometrists and nurses working independently and conjointly in vision screening of schoolchildren are compared. Very few studies in the literature have examined the difference in referral rate; this difference is important because of the shortage of qualified manpower to screen the large number of children in the present school population. The study determined that the nurses correctly referred a greater percentage of children following an educational program and collaboration with the optometrist, but this increase in referral was not statistically significant.
Random dot stereogram E in vision screening of children.
The random dot stereogram E (RDE) has been shown to be a simple and effective test for the detection of binocular abnormalities and defective visual acuity in children. We determined the validity of the RDE as a screening test for reduced visual acuity, amblyopia and strabismus in two separate populations of children. A nonselective group of 100 school children (aged 5 to 15 years) who presented consecutively to the ophthalmology department at Auckland Public Hospital were tested with the RDE. All cases of amblyopia and strabismus were detected by the RDE. Similar screening with the RDE test of 168 preschool children (aged three to four years) in the community resulted in an unacceptably high over-referral rate. The test was unreliable in the preschool age group because of difficulty in distinguishing between test failure and non-cooperation with the test. The low positive predictive value of the test in the younger age group suggests the test to be unsuitable for preschool vision screening.
The influence of clinical judgment on the rate of referral from a school vision screening program.
It has been observed that black preschool children low income families have a higher than average rate of referral from a school vision screening program. One potential contributing factor results from the fact that examiners often modified the referral criteria based on their clinical judgment. This study was designed to investigate the influence of the application of clinical judgment on the proportion of referrals as a function of ethnicity and socioeconomic income level. The results suggest that modifying the referral criteria based on clinical judgment does not significantly influence the proportion of referrals based on ethnicity or socioeconomic income level.