Treatment outcome in 344 children with amblyopia from a population-based birth-cohort (N=10811)

Abstract

Purpose : The OVAS Study assessed the effectiveness of preverbal orthoptic tests at age 6-24 months in population-wide screening and found these to be ineffective (doi: 10.1111/aos.14859). Amblyopia was found in 344 out of 10811 children - 46 were diagnosed outside screening - and their visual acuity and orthoptic findings were recorded after referral, mostly at the age of 36 or 45 months when visual acuity was measured. We now report on treatment outcome in these children at age 8-10.

Methods : A birth-cohort (N=10811) born between July 2011 and June 2012 that was screened at 134 youth-healthcare centres in the north-eastern part of the Netherlands was followed. When children were referred to orthoptists after positive screening, the cause and severity of the amblyopia were reported by treating orthoptists when amblyopia was suspected. In the current study, these orthoptists reported again on visual acuity at age 8-10, with cycloplegic refraction, glasses prescribed, occlusion treatment, kind of strabismus and surgery. Finally the orthoptists were asked whether, in hindsight, true amblyopia had been present and what had caused the amblyopia.

Results : Visual acuity at age 8-10 was reported for 303 out of 344 children. Half of the remaining 41 children were too young to measure visual acuity when they were last seen. Other children did not attend appointments. Visual acuity in the amblyopic eye was 0.037 SD 0.108 logMAR, in the better eye -0.008 SD 0,081 logMAR. The difference between the two eyes averaged 0.044 SD 0.084 logMAR (N=303). Seven children had two lines difference or more. Four of 303 children had 0.3 logMAR visual acuity in the amblyopic eye, two had 0.4, two had 0.52 and two had 0.7 or worse. In 41.2 % of cases the orthoptists did not consider true amblyopia to have been present, but that included cases of refractive amblyopia that were rapidly cured by glasses.

Conclusions : Population-wide screening and orthoptic treatment for amblyopia is very effective and reaches high coverage in the Netherlands, although occasionally amblyopia persists beyond age 6.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.