Update of the Evidence From Randomized Controlled Trials, 1999-2003: Screening for Visual Impairment in Children Younger than Age 5 Years: Table 1. RCTs of Amblyopia Screening in Children Younger than Age 5 Years Published Since 1999

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Table 1. RCTs of Amblyopia Screening in Children Younger than Age 5 Years Published Since 1999

Author, Year

Population

Setting

Exclusions

Definitions of Amblyopia

Intervention

Outcomes

Results

Study Quality

Williams et al, 2002²

3,490

Newborns and their mothers; nested RCT in ALSPAC; trial included children born during the last 6 mos of the study period

Southwest England

Born during the first 15 mos of cohort study; parents declined, sibling already in study

Amblyopia A: interocular difference in acuity ≥0.2 LogMAR; Amblyopia B: visual acuity in amblyopic eye worse than 0.3 LogMAR

Intensive orthopic screening in 2,029 (8,12,18, 25, 31, 37 mos) vs control screening in 1,490 (usual care and 1 orthopic exam at 37 mos); all screenings: cover test and non-cycloplegic autoretraction; 8,12 mos: Cardiff Cards; 18, 25, 31 mos: Cardiff Cards and Kays Picture test; 37 mos: Kays Picture (enhanced) and HOTV letters; any child failing acuity or cover tests were referred to hospital eye service; referrals were not made based on autoretraction testing until 37 mos

All children assessed at 7.5 yrs with LogMAR; outcomes include prevalence of amblyopia and visual acuity in worse eye after treatment

Amblyopia at 7.5 yrs was less prevalent in intensive screening group than control group; Amblyopia A: 1.45% intensive vs 2.66% control (P = 0.06); Amblyopia B: 0.63% intensive vs 1.81% control (P = 0.02)

Cumulative incidence of amblyopia in each group was similar; residual amblyopia was more likely despite treatment in control (10/40) than intensive group (3/40); Amblyopia A: OR = 1.56 (95% CI, 0.62-3.92); Amblyopia B: OR = 4.11 (1.04-16.29)

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 vs 0.26 LogMAR units; P <0.001)

Higher proportion of the children who were treated for amblyopia had been seen in the eye clinic before 3 yrs of age in the intensive group than in the control group (48% vs 13%, P = 0.0002)

Fair

Almost half did not have the 7.5 yr followup examination in both the intensive and usual care groups; completers differed from non-completers; not known if completers in intensive group differed from those in usual care group

Williams et al, 2001³

3,490

Children born in the last 6 mos of the ALSPAC study

Southwest England

Born during the first 15 mos of cohort study; parents declined, sibling already in study

Interocular difference of 0.01 LogMAR units or equivalent using a recognition test with full spectacle correction

Control group (n = 1,461): usual care by GPs or nurses (questions on family history, observation of visual behavior, cover test) at 8 and 18 mos, orthopic exam at 37 mos Intervention group (n = 2,029): usual care and orthopic testing at 8, 12, 18, 25, 31, 37 mos; for visual acuity: observing behavior when either eye occluded (all screenings); Cardiff Cards (8, 12, 18, 25, 31 mos); Kays Picture Test (25, 31 mos); for occular alignment: cover test (all screenings); for stereopsis: Lang tests 1 & 2 (18, 25, 31 mos); Frisby test: (12, 18, 25, 31 mos); for motor fusion: 20 Dioptre base-out test (all screenings); non-cycloplegic photorefraction: (all screenings); referrals based on testing criteria

Number of children from each group referred to the Eye Hospital and diagnosed with strabismus or amblyopia before 37 mos

Sensitivities of program estimated by final orthoptic assessment at 37 mos

Intensive group yielded more children with amblyopia (1.6% vs 0.5%, P <0.01) and was more specific than the control group (4.5% false positives vs 7.5% for controls, P <0.01); cover test with either photorefraction or acuity testing at 37 mos provided the best sensitivity and specificity: 82%-84% sensitivity, 97%-98% specificity, 63%-73% PPV, 99% NPV

Fair

Note: ALSPAC, Avon Longitudinal Study of Parents and Children; CI, confidence interval; GP, general practitioner; NPV, negative predictive value; OR, odds ratio; PPV, positive predictive value; RCT, randomized controlled trial.

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