Children unable to perform screening tests in vision in preschoolers study: proportion with ocular conditions and impact on measures of test accuracy

PURPOSE: To examine the relative prevalence of ocular conditions among children who are unable to perform preschool vision screening tests and the impact on measures of screening test performance. METHODS: Trained nurse and lay screeners each administered a Lea Symbols visual acuity (VA) test (Good-Lite, Inc., Steamwood, IL), Stereo Smile II test (Stereo Optical, Inc., Chicago, IL), and Retinomax Autorefractor (Right Manufacturing, Virginia Beach, VA), and SureSight Vision Screener (Welch Allyn, Inc., Skaneateles Falls, NY) examinations to 1475 children who later received a comprehensive eye examination to identify amblyopia, strabismus, significant refractive error, and unexplained reduced VA. The outcomes of the examination for children for whom screeners were unable to obtain results (Unables) were compared to the outcomes of children who passed and children who failed each screening test. When estimating sensitivity, specificity, and positive and negative predictive values (PPV and NPV), Unables were classified as either screening failures or screening passers. RESULTS: Less than 2% of children were classified as Unables for each test. The percentage with an ocular condition was at least two times higher for Unables than for screening passers for six of the eight modes of screening (P < 0.05). Considering Unables as screening failures, rather than screening passers, increased the estimate of sensitivity by 1% to 3% (depending on test) and decreased the estimate of specificity by 0% to 2%; PPV decreased by 0% to 4% for most tests, whereas NPV increased by <1%. CONCLUSIONS: Preschool children who are unable to perform VIP screening tests are more likely to have vision disorders than are children who pass the tests. Because < or =2% of children were unable to do each test, referring these children for an eye examination had little impact on the PPV and NPV of the tests, as administered in VIP.     

Eye conditions among 5- to 7-year-old Asian-Pacific Islander schoolchildren in Southern California.

BACKGROUND: The prevalence rates and specific risk factors for development of eye conditions among Asian-Pacific Islander schoolchildren are unknown. This information is necessary to understand their eye care needs and to improve access to eye care for this rapidly growing population. METHODS: Data obtained from a computer database of vision screening examinations conducted by the UCLA Mobile Eye Clinic from October 1987 through December 1996 were analyzed for 2,687 Asian-Pacific Islander schoolchildren between 5 and 7 years of age. RESULTS: Myopia (8.9%) and astigmatism (15.8%) represented the majority of visual disorders. Mean myopic refractive error was -1.21 +/- 0.83 D among bilateral myopes. Color-vision deficiency was prevalent among 2.8% of male children, extraocular muscle imbalance among 3.0% of children, and amblyopia among 1.0% of children. All other conditions were present in less than 4% of children screened. CONCLUSIONS: Asian-Pacific Islander schoolchildren may be at higher risk for development of juvenile myopia than white, Hispanic, and African-American children. Prevalence rates of other disorders are comparable to those obtained for other ethnic groups. This information can be used in planning to meet the eye care needs of Asian-Pacific Islander schoolchildren.     

The Seoul Metropolitan Preschool Vision Screening Programme: results from South Korea

AIM: To report on a new model of preschool vision screening that was performed in metropolitan Seoul and to investigate the distribution of various ocular disorders in this metropolitan preschool population. METHODS: Vision screening was conducted on 36 973 kindergarten children aged 3-5 years in a stepwise manner. The first step was home screening using a set of five picture cards and a questionnaire. The children who did not pass the first step (VA <0.5 in at least one eye or any abnormal responses on the questionnaire) were retested with regular vision charts at the regional public healthcare centres. After this retest, some children were referred to ophthalmologists. The referral criteria for visual acuity were <0.5 at 3 years and <0.63 at 4 or 5 years in at least one eye. RESULTS: Of those screened, 7116 (19.2%) children did not pass the home screening tests and 2058 (28.9%) out of the 7116 were referred. The results of the ophthalmological examination in eye clinics were only available for 894 children (43.4%) of those who were referred. The rest of the children did not visit ophthalmologists because they had been checked at an eye clinic, were currently under treatment, or for personal reasons. Refractive errors were found in 608 (1.6%) children. Astigmatism was associated in 78.2% of ametropes. Amblyopia was discovered in 149 (0.4%) children and refractive error was the major aetiology with a predominant rate (82.5%). Manifest strabismus was detected in 52 children. The positive predictive value of vision screening for any ophthalmological disorder was 0.77, and 0.49 for significant disorders requiring treatment. CONCLUSIONS: This preschool vision screening model was highly accessible to the children and their parents, easy to administer, and effective to detect a variety of ocular disorders. However, the participation rate of the referred children in the examinations by ophthalmologists was quite low. The performance and efficiency of this screening programme need to be optimised with further revision.     

Loss of visual acuity due to eye injuries among 6292 school children in the Sultanate of Oman

PURPOSE: In 1992-94 a nation-wide survey in primary schools in the Sultanate of Oman for ocular disorders was conducted. This report focuses on the prevalence of visual acuity loss after injury. METHODS AND MATERIAL: A random selection of 6,292 children from Grades 1 and 6 from all primary schools in the country provided the research sample. Children who failed the visual acuity screening test received a complete "on the spot" eye examination by the pediatric ophthalmologist. Results: 12 children were found to have monocular low vision (VA <0.3 to amaurosis) caused by injury. Total prevalence for loss of vision in one eye was 0.19%, with 0.15% in 6-year-olds and 0.25% in 12-year-olds Traumatic cataracts were noted in 4 children, 3 of these were in need of surgery. One child had aphakia after trauma surgery and needed a secondary lens implant. CONCLUSION: Altogether the prevalence of traumatic monocular visual damage in our study was 0.19%. Next to amblyopia, injury is the main reason for monocular loss of vision in childhood, however, both are preventable. Information about trauma prevention and the need for adequate ophthalmic care should be emphasized. Regular and repeated screening of visual acuity in children is essential.     

Refractive error and visual impairment in African children in South Africa

PURPOSE: To assess the prevalence of refractive error and visual impairment in school-aged African children in South Africa. METHODS: Random selection of geographically defined clusters was used to identify a sample of children 5 to 15 years of age in the Durban area. From January to August 2002, children in 35 clusters were enumerated through a door-to-door survey and examined in temporary facilities. The examination included visual acuity measurements, ocular motility evaluation, retinoscopy and autorefraction under cycloplegia, and examination of the anterior segment, media, and fundus. In nine clusters, children with reduced vision and a sample of those with normal vision underwent independent replicate examinations for quality assurance. RESULTS: A total of 5599 children living in 2712 households were enumerated, and 4890 (87.3%) were examined. The prevalence of uncorrected, presenting, and best-corrected visual acuity of 20/40 or worse in the better eye was 1.4%, 1.2%, and 0.32%, respectively. Refractive error was the cause in 63.6% of the 191 eyes with reduced vision, amblyopia in 7.3%, retinal disorders in 9.9%, corneal opacity in 3.7%, other causes in 3.1%, and unexplained causes in the remaining 12.0%. Exterior and anterior segment abnormalities were observed in 528 (10.8%) children, mainly corneal and conjunctival. Myopia (at least -0.50 D) in one or both eyes was present in 2.9% of children when measured with retinoscopy and in 4.0% measured with autorefraction. Beginning with an upward trend at age 14, myopia prevalence with autorefraction reached 9.6% at age 15. Myopia was also associated with increased parental education. Hyperopia (+2.00 D or more) in at least one eye was present in 1.8% of children when measured with retinoscopy and in 2.6% measured with autorefraction, with no significant predictors of hyperopia risk. CONCLUSIONS: The prevalence of reduced vision is low in school-age African children, most of it because of uncorrected refractive error. The high prevalence of corneal and other anterior segment abnormalities is a reflection of the inadequacy of primary eye care services in this area.     

Ocular and visual defects amongst people with intellectual disabilities participating in Special Olympics

PURPOSE: To analyse data from vision screening of people with intellectual disabilities from the UK participating in Special Olympics during the National Summer Games in Cardiff 2001, in order to determine visual status and access to eye care. METHODS: Athletes were invited to take part in vision screening, according to Special Olympics protocols. RESULTS: Testability rates were high. Findings confirmed the high prevalence of eye and vision defects reported in other studies of people with intellectual disabilities. In particular, visual acuity was below normal for most athletes. Significant improvement to acuity could be achieved with spectacles although correction after full refraction did not always provide normal vision. Over 40% of athletes undergoing full refraction had below normal corrected acuity. CONCLUSIONS: Athletes with intellectual disabilities were no more likely to access eye care and have adequate spectacle correction than other people with intellectual disabilities. Optometrists and carers need to be aware of the high prevalence of defects and the importance of regular eye examinations in people with intellectual disabilities.     

Preschool vision screening: outcome of children referred to the hospital eye service.

AIMS: To assess the outcome of children referred to the hospital eye service (HES) from an orthoptist based preschool vision screening programme. METHODS: A retrospective study was conducted of children referred from screening during a 2 year period. Children were screened by community orthoptists at 3 1/2 years of age. The main outcome measures were (1) HES findings for children referred from screening, and (2) visual outcome for amblyopic children after completion of treatment. RESULTS: The attendance rate at screening was 79.3% (6794 children): 348 children (5.1% of those screened) were referred to the HES. The HES findings were refractive error (32.9%), amblyopia (29.9%), false positive referral (20.1%), strabismus (13.2%), and other ocular disorders (3.9%). The positive predictive value of screening was 79.9%. Screening detected 48 children with straight eyed amblyopia and 43 children with strabismic amblyopia. A visual acuity of 6/9 or better in the amblyopic eye was achieved by 87.2% of straight eyed amblyopes and 64.3% of strabismic amblyopes (chi 2 = 5.27, p = 0.02). Residual amblyopia of 6/24 or worse occurred in only 5.6% of amblyopic children. CONCLUSION: Most amblyopic children detected by preschool vision screening achieve a good visual outcome with treatment. While treatment earlier in the sensitive period might be expected to give improved results, it remains to be demonstrated that preschool screening results in a better outcome than screening at school entry. Preschool vision screening also detects a significant number of children without amblyopia who have reduced vision due to refractive errors. This group of children must be included in any analysis of the cost effectiveness of preschool vision screening.     

A model of the prevalence and incidence of low vision and blindness among adults in the U.S.

Population-based vision screening studies of the prevalence rate of low vision and blindness in the U.S. are reviewed to evaluate the sources of disagreement among studies. The major reasons that studies disagree on prevalence rate estimates are differences in best-corrected visual acuity criteria for low vision and differences in the age range of the oldest age category. When corrections are made for these differences, the results of all prevalence rate studies, except the Mud Creek Valley Study, fit the same prevalence rate vs. age function. The greater prevalence rate of low vision and blindness for each age category that was observed in the Mud Creek Valley Study can be attributed to the higher prevalence rate of cataract associated with a paucity of health care services in the Mud Creek Valley population. The time-derivative of the prevalence rate vs. age function fit to the data provided an estimate of the annual incidence rate of low vision and blindness vs. age. The estimated annual incidence agreed with estimates from unpublished 8-year incidence data of the Baltimore Eye Survey. The incidence rate of low vision and blindness for Americans aged 40 to 60 years is higher among blacks than among whites. For Americans greater than age 60 years, the incidence rate for whites exceeds that for blacks. This observation probably reflects the different natural histories of glaucoma, a leading cause of low vision and blindness among black Americans, and age-related macular degeneration, a leading cause of low vision and blindness among white Americans. Using the age-dependent models of prevalence rate of low vision and blindness for white and black populations, an estimated 1.5 million Americans over age 45 years have a best-corrected visual acuity in the better eye that is < or = 20/70. Based on the incidence rate estimates, approximately 240,000 new cases of low vision and blindness occur each year. With the aging of the U.S. population, that number is expected to double over the next 25 years.     

The prevalence of strabismus and amblyopia in Japanese elementary school children

BACKGROUND: The purpose of this study is to elucidate the prevalence of strabismus and amblyopia in a large population of Japanese elementary school children, from Grade 1 to Grade 6, ages ranging from 6 to 12 years. The School Health Law requires that all pupils in Grade 1 to Grade 6 be examined for vision and eye problems. Visual acuity testing is done by school teachers and eye disease screening by school ophthalmologists. Pupils with suspected ocular diseases are further examined by extramural ophthalmologists and the results reported back to the schools. The schools then summarize and send uncorrected visual acuity and ocular disease incidence, together with other health statistics, to the municipal education committees. The data are forwarded to the Prefecture Governments and finally submitted to the Education Ministry of the Central Government. Both the Prefecture Governments and the Education Ministry publicize the school health statistics on their websites. The prevalence of strabismus and amblyopia remains unknown from these data because both diagnoses are included under the heading, eye diseases. METHODS: Questionnaires asking about the numbers of children with different types of strabismus and amblyopia were sent to all elementary schools in Okayama Prefecture and the results were summarized. RESULTS: The number of children covered by the return of questionnaires was 86,531 (76.4%) of 113,254 total pupils in Grade 1 to Grade 6 in Okayama Prefecture in the year 2003. The total numbers of children with strabismus and amblyopia were 1,112 (1.28%) and 125 (0.14%), respectively. The numbers of children with any type of exotropia and any type of esotropia were 602 (0.69%) and 245 (0.28%), respectively. The major types of strabismus and amblyopia were intermittent exotropia in 109 children (0.12%), accommodative esotropia in 19 children (0.02%), anisometropic amblyopia in 23 children (0.03%), and ametropic amblyopia in 12 children (0.01%). The number of children with strabismus of unknown type was 245 (0.28%) while the number of children with amblyopia of unknown type was 81 (0.09%). CONCLUSIONS: The prevalence rates of strabismus and amblyopia in this population of Japanese elementary school children were lower than those reported in Western countries. The exotropia/esotropia ratio were increased in comparison with past studies in Japan. The school eye doctors need to be more diligent in identifying and diagnosing various types of strabismus and amblyopia in order to contribute to the school vision screening program already in place in Japan