Effectiveness of screening for amblyopia and other eye disorders in a prospective birth cohort study.

OBJECTIVE: To establish whether the current vision screening practice in the Netherlands is effective in preventing permanent visual loss and to estimate the sensitivity of the programme. SETTINGS: In the Netherlands, all children are invited for preverbal (1, 3, 6-9 and 14-24 months) and preschool (36, 45, and 60-72 months) vision screening. Screening attendance is high, but the effectiveness in reducing amblyopia is unknown. METHODS: In a 7-year cohort study, 4624 children born in the city of Rotterdam between 16 September 1996 and 15 May 1997 were followed through all routine vision screening examinations. At age seven, visual acuity (VA) of children still living in Rotterdam was assessed by study orthoptists. In case of VA > 0.1 logMAR in one or both eyes, two or more logMAR lines of interocular difference or eye disorders like strabismus, children underwent a more intensive eye examination. RESULTS: Attendance at the 9-month screening was 89%, decreasing to about 75% at later examinations. Of preverbal tests, 2.5% were positive, and of preschool tests, 10%. In total, 19% of children had a positive vision screening test at least once. Amblyopia prevalence was 3.4%. Sensitivity of the vision screening programme was 73% and specificity 83%. At age seven, 0.7-1.2% (confirmed vs final exam) of the children had a VA > 0.3 logMAR in the worse eye compared with 2-3.9% (in literature) reported prevalence in non-screening situations. Children who were less frequently screened had a higher chance of poor vision (>0.3 logMAR) at age seven. CONCLUSION: The Dutch child vision screening programme may reduce the risk of persistent amblyopia (VA > 0.3 logMAR) at age seven by more than half.

Determinants and outcome of unsuccessful referral after positive screening in a large birth-cohort study of population-based vision screening.

PURPOSE: The efficacy of population-based vision screening is hampered by unsuccessful referral after a positive screening test. We studied the nature and causes of unsuccessful referral in a 7-year birth cohort study of vision screening in Rotterdam, the Netherlands. METHODS: All parents of children who had been unsuccessfully referred were asked whether they recalled the referral. Reasons for noncompliance, if any, were identified using semi-structured interviews. Screening records were checked for written evidence of the referral. The parents' fluency in Dutch and their socioeconomic status were also assessed. RESULTS: Of the 561 screen-positive children, 129 (23%) had not been referred successfully. For the current study, 97 parents were successfully contacted. Of these, 14 parents had been willingly noncompliant and 83 said they were unaware of the referral, with 47% having poor to moderate fluency in Dutch. In 53 cases, the screening charts contained no written evidence of any referral. Amblyopia was identified in 3 of the unsuccessful referrals. CONCLUSIONS: In this population-based screening program, 1 of 4 positively screened children was not successfully referred. Apart from parental noncompliance, the unsuccessful referrals can be explained by miscommunication, deficient documentation, and physician noncompliance with screening guidelines. An effective monitoring feedback system may improve the efficacy of child vision screening.

Rotterdam AMblyopia screening effectiveness study: detection and causes of amblyopia in a large birth cohort.

PURPOSE. The Dutch population-based child health monitoring program includes regular preverbal (age range, 1-24 months) and preschool (age range, 36-72 months) vision screening. This study is on the contribution of an organized vision screening program to the detection of amblyopia. METHODS. A 7-year birth cohort study of 4624 children was started in 1996/1997 in Rotterdam. Vision screening data were obtained from the child screening centers. Treating orthoptists working at the regional ophthalmology departments provided information about diagnosis and treatment. The diagnosis was reviewed by two experts. The parents provided additional information on their child's eye history through written questionnaires and telephone interviews. At age 7 years, the children underwent a final examination by the study orthoptists. RESULTS. Of the 3897 children still living in Rotterdam by 2004, 2964 (76.1%) underwent the final examination. Amblyopia was diagnosed in 100 (3.4%) of these (95% CI, 2.7-4.0). At age 7, 23% had visual acuity >0.3 logMAR. Amblyopia was caused by refractive error (n = 42), strabismus (n = 19), combined-mechanism (n = 30), deprivation (n = 7), or unknown (n = 2). Eighty-three amblyopia cases had been detected before age 7. Amblyopia detection followed positive results in vision screening in 56 children, either preverbal (n = 15) or preschool (n = 41). Twenty-six other amblyopes were self-referred (n = 12, before a first positive screening test), especially strabismic or combined-mechanism amblyopia; data were uncertain for one other positively screened amblyopic child. Amblyopia remained undetected until age 7 due to unsuccessful referral (n = 4, three with visual acuity >0.3 logMAR at age 7) or false-negative screening (n = 13). CONCLUSIONS. Most cases of amblyopia were detected by vision screening with visual acuity measurement. Preverbal screening contributed little to the detection of refractive amblyopia.