Non-concordance in amblyopia treatment: the effective use of 'smileys'

The success of any specific occlusion regimen is limited by the level of concordance, which is difficult to measure accurately in patching treatment. The aim of this study was to investigate prospectively the concordance rate of a group of children with strabismic and/or anisometropic amblyopia using a schematic diary based on completing 'smiley' images, filled in by the child under parental supervision, and to assess the effect of correlates such as initial visual acuity, age, and total and daily occlusion time on concordance.

We recruited 51 amblyopic children aged 13 months to 12 years (mean 6.57 +/- 2.82). The median duration of treatment was 16 weeks. Non-concordance was defined as occluding less than 75% of the prescribed time and was analyzed using a concordance index calculated from occlusion time recorded in the diary/prescribed occlusion time.

Of the 51 patients followed prospectively, 12 (23.5%) failed to return their diaries (Group 1); 27 (52.9%) complied with occlusion (Group 2); and 12 (23.5%) failed to comply with occlusion completely (Group 3). The total proportion of non-concordance was 47.1% (Group 1 + Group 3). Concordance was not significantly related to initial visual acuity (r = -0.22, p = 0.19), patient age (F = 1.0787, p = 0.349) or total occlusion time (X2 = 2.779, p = 0.249), but the number of daily occlusion hours showed significant difference in Group 1 (X2 = 15.894, p = 0.000). When the three groups were compared for change in visual acuity, a significant difference was found between group 1 and group 2 (X2 = 6.125, p = 0.047).

The substantial proportion of non-concordance in our study suggests that, although useful for recording purposes, parental diaries may not be stimulating enough to increase the overall level of concordance. Therefore, other forms of monitoring need to be explored.