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Alaska Blind Child Discovery

A cooperative, charitable research project to vision screen every preschool Alaskan

Screening Outcome Studies


Kvarnstrom G, Jakobsson P, Lennerstrand G. Screening for visual and ocular disorders in children, evaluation of the system in Sweden. Acta Paediatr 1998;87(11):1173-1179.
The aim of this study was to evaluate the visual screening system in Sweden. We have made a retrospective investigation of the results of screening for ocular disease and visual impairment of all children born in 1982 in three Swedish communities. The records from screening examinations from 0 to 10 y and from diagnostic follow-up at the departments of ophthalmology that the children were referred to were inspected. The data were used to evaluate the efficiency of the Swedish visual screening system. The study included 3126 children. The attendance rate at the 4-y examination was better than 99%. The sensitivity of the 4- and 5.5-y screening examinations was on the average 92% and the specificity was 97%. The average number of false negative cases at 4 y was 5.6 in 1000 (0.56%). With this screening and subsequent diagnosis and treatment, the prevalence of amblyopia at different levels of visual acuity at the age of 10y was: 0.06% with visual acuity < or = 0.1, 0.9% with visual acuity < or = 0.5 and 1.7% with visual acuity < or = 0.7. In spite of largely unchanged pressure of amblyogenic factors in the population, the prevalence of deep and moderate amblyopia has been markedly reduced by screening and early treatment.

Eibschitz-Tsimhoni M, Friedman T, Naor J, Eibschitz N, Friedman Z. Early screening for amblyogenic risk factors lowers the prevalence and severity of amblyopia. J AAPOS 2000;4(4):194-199.
PURPOSE: To evaluate the efficacy of a mass screening program for amblyopia and amblyogenic risk factors in infants. METHODS: Since 1968, children between the ages of 1 and 2(1/2) years in the city of Haifa, Israel, have been systematically screened for amblyopia and amblyogenic risk factors. The screening is performed by the Ophthalmology Department of Bnai-Zion Medical Center (formerly known as Rothchild Hospital). In 1995, we compared the prevalence and severity of amblyopia in two populations of 8-year-old children in elementary school: one group was a cohort of 808 children from the city of Haifa and its vicinity, who had been screened in infancy (between 1988 and 1990); and the second group, the control group, was a cohort of 782 children from Hadera and its vicinity, where this early screening program is not conducted. Amblyopia was defined as corrected visual acuity of &lt; or =5/10 (20/40), or &gt;1 line difference in corrected visual acuity between the two eyes. Referral rate, treatment rate, sensitivity, specificity, and positive predictive value and negative predictive value of the screening test in detecting factors that later resulted in the development of amblyopia were examined. RESULTS: The prevalence of amblyopia in the 8-year-old population screened in infancy was found to be 1.0% compared with 2.6% in the 8-year-old population that had not been screened in infancy (P =.0098). The prevalence of amblyopia with visual acuity of &lt; or =5/15 (20/60) in the amblyopic eye was 0.1% in the screened population compared with 1.7% in the non-screened population (P =.00026). In the screened infant population, 3.6% were referred from the screening examination to a confirmatory examination and 2.2% were treated. The screening examination had a sensitivity of 85.7% and a specificity of 98.6% for amblyopia. The positive predictive value of the screening examination was 62.1% and the negative predictive value was 99.6%. CONCLUSIONS: The screening program for amblyopia and amblyogenic risk factors in infants, followed by appropriate treatment, is effective in significantly reducing the prevalence and severity of amblyopia in children.

Williams C, Northstone K, Harrad RA, Sparrow JM, Harvey I. Amblyopia treatment outcomes after screening before or at age 3 years: follow up from randomised trial. BMJ 2002;324(7353):1549.
Objective: To assess the effectiveness of early treatment for amblyopia in children. Design: Follow up of outcomes of treatment for amblyopia in a randomised controlled trial comparing intensive orthoptic screening at 8, 12, 18, 25, 31, and 37 months (intensive group) with orthoptic screening at 37 months only (control group). Setting: Avon, southwest England. Participants: 3490 children who were part of a birth cohort study. Main outcome measures: Prevalence of amblyopia and visual acuity of the worse seeing eye at 7.5 years of age. Results: Amblyopia at 7.5 years was less prevalent in the intensive group than in the control group (0.6% v 1.8%; P=0.02). Mean visual acuities in the worse seeing eye were better for children who had been treated for amblyopia in the intensive group than for similar children in the control group (0.15 v 0.26 LogMAR units; P<0.001). A higher proportion of the children who were treated for amblyopia had been seen in a hospital eye clinic before 3 years of age in the intensive group than in the control group (48% v 13%; P=0.0002). Conclusions: The intensive screening protocol was associated with better acuity in the amblyopic eye and a lower prevalence of amblyopia at 7.5 years of age, in comparison with screening at 37 months only. These data support the hypothesis that early treatment for amblyopia leads to a better outcome than later treatment and may act as a stimulus for research into feasible screening programmes.(

Donahue SP. Relationship between anisometropia, patient age, and the development of amblyopia. Am J Ophthalmol 2006;142(1):132-140.
PURPOSE: Previous studies evaluating the effect of anisometropia on amblyopia development have been biased because subject selection occurred as a result of decreased acuity. Photoscreening identifies anisometropic children in a manner that is not biased by acuity, and allows an opportunity to evaluate how patient age influences the prevalence and depth of amblyopia. DESIGN: Retrospective observational study of preschool children with anisometropia. METHODS: A statewide preschool photoscreening program screened 119,311 children and identified 792 with anisometropia >1.0 diopters. We correlated age with visual acuity and amblyopia depth. Results were compared with 562 strabismic children similarly identified. RESULTS: Only 14% (six of 44) of anisometropic children aged 1 year or younger had amblyopia. Amblyopia was detected in 40% (32 of 80) of 2-year-olds, 65% (119 of 182) of 3-year-olds, and 76% of 5-year-olds. Amblyopia depth also increased with age. Moderate amblyopia prevalence was 2% (ages 0 to 1), 17% (age 2), and rose steadily to 45% (ages 6 to 7). Severe amblyopia was rare for children aged 0 to 3, 9% at age 4, and 14% at age 5. Children with strabismus had a relatively stable prevalence (30% ages 0 to 2; 42% ages 3 to 4; and 44% ages 5 to 7) and depth of amblyopia. CONCLUSIONS: Younger children with anisometropia have a lower prevalence and depth of amblyopia than older children. By age 3, when most children undergo traditional screening, amblyopia has usually already developed. New vision screening technologies that allow early detection of anisometropia provide ophthalmologists an opportunity to intervene early, perhaps retarding or even preventing the development of amblyopia.

Atkinson J, Braddick O, Nardini M, Anker S. Infant hyperopia: detection, distribution, changes and correlates-outcomes from the cambridge infant screening programs. Optom Vis Sci 2007;84(2):84-96.
PURPOSE.: To report on two population screening programs designed to detect significant refractive errors in 8308 8- to 9-month-old infants, examine the sequelae of infant hyperopia, and test whether early partial spectacle correction improved visual outcome (strabismus and acuity). The second program also examined whether infant hyperopia was associated with developmental differences across various domains such as language, cognition, attention, and visuomotor competences up to age 7 years. Linked programs in six European countries assessed costs of infant refractive screening. METHOD.: In the first program, screening included an orthoptic examination and isotropic photorefraction, with cycloplegia. In the second program we carried out the same screening procedure without cycloplegia. Hyperopic infants (>/=+4 D) were followed up alongside an emmetropic control group, with visual and developmental measures up to age 7 years, and entered a controlled trial of partial spectacle correction. RESULTS.: The second program showed that accommodative lag during photorefraction with a target at 75 cm (focus >/=+1.5 D) was a marker for significant hyperopia. In each program, prevalence of significant hyperopia at 9 to 11 months was around 5%; manifest strabismus was 0.3% at 9 months and 1.5 to 2.0% by school age. Infant hyperopia was associated with increased strabismus and poor acuity at 4 years. Spectacle wear by infant hyperopes produced better visual outcome than in uncorrected infants, although an improvement in strabismus was found in the first program only. The corrections did not affect emmetropization to 3.5 years; however, both corrected and uncorrected groups remained more hyperopic than controls in the preschool years. The hyperopic group showed poorer overall performance than controls between 1 and 7 years on visuoperceptual, cognitive, motor, and attention tests, but showed no consistent differences in early language or phonological awareness. Relative cost estimates suggest that refractive screening programs can detect visual problems in infancy at lower overall cost than surveillance in primary care. CONCLUSIONS.: Photo/videorefraction can successfully screen infants for refractive errors, with visual outcomes improved through early refractive correction. Infant hyperopia is associated with mild delays across many aspects of visuocognitive and visuomotor development. These studies raise the possibility that infant refractive screening can identify not only visual problems, but also potential developmental and learning difficulties.

Kirk VG, Clausen MM, Armitage MD, Arnold RW. Preverbal photoscreening for amblyogenic factors and outcomes in amblyopia treatment: early objective screening and visual acuities. Arch Ophthalmol 2008;125(4):489-492.

BACKGROUND: Previous studies have suggested that infant photoscreening yields better results than visual acuity screening in preschool-aged children. With conventional vision screening, the patient must be able to provide monocular visual acuity cooperation, whereas objective screening for amblyogenic factors can be done at much younger ages. METHODS: From February 1996 through February 2006, Alaska Blind Child Discovery photoscreened 21 367 rural and urban Alaskan children through grade 2, with an 82% positive predictive value (ie, true number of those referred); 6.9% were referred for a complete eye examination and treatment. All "referred" interpreted images for children younger than 48 months who were then followed up and treated for more than 2 years were reviewed to determine whether treatment was successful. RESULTS: Of 411 "positive" screening photos from children younger than 4 years, 94 patients had more than 2 years follow-up. The 36 children photoscreened before age 2 years had a mean treated visual acuity of 0.17 logarithm of the minimum angle of resolution (logMAR), which was significantly better than that of 58 children screened between ages 25 and 48 months (mean, 0.26 logMAR). Despite similar levels of amblyogenic risk factors, the proportion of children failing to reach a visual acuity of 20/40 was significantly less among those screened before age 2 years (5%) than in those screened from ages older than 2.0 years and younger than 4.0 years (17%). CONCLUSION: Very early photoscreening yields better visual outcomes in amblyopia treatment compared with later photoscreening in preschool-aged children.
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