This difference in treatment duration limits the validity of comparing responsivity across children, especially because gains had not plateaued in at least some children who were released from BBV. However, we can still consider the effect of treatment length and compliance on the therapeutic outcome. Standard occlusion therapies, which are likely to improve acuity in 50% to 85% of children,
58 are fundamentally limited by levels of concordance (i.e., agreement on treatment regimen between patient and clinician) falling below 50%,
56 and compliance, especially at a young age (<50% in 4- to 7-year-old children
16). Recent studies of various binocular treatments have shown that children whose compliance is less than 50% either showed significantly lower gain in logMAR acuity
38 or required longer treatment durations to reach comparable outcomes.
59 In older children, the success of monocular training (in addition to patching) was related to the total amount of training (across sessions), provided a minimum daily compliance level of 15 minutes of practice per session was met.
42 In our study, on average, children who spent 8 or 16 weeks on BBV showed high levels of compliance (87% ± 21% and 84% ± 28%), with similar gains in AE acuity (0.2 ± 0.24 and 0.24 ± 0.11 logMAR, respectively). Those eligible for 24 weeks received 98% ± 46% of the prescribed dose and gained 0.41 ± 0.16 logMAR (see also
Supplementary Materials). Interestingly, those children whose BBV treatment lasted longer spent a higher proportion of days on treatment (66%, 70%, and 71%, respectively over 8, 16, and 24 weeks). These results suggest that high levels of compliance, as both daily and total perseverance, can produce positive treatment outcomes (although such correlations did not reach significance in our study, perhaps due to the generally high levels of compliance). More generally, alternative treatments (to replace or augment occlusion) engage higher levels of compliance than occlusion alone.
60 Leaving open the question of whether occlusion is necessary, these studies highlight the importance of compliance in amblyopia treatment. Given the lack of clarity regarding the mechanism supporting improvements in vision, further study is required to determine the extent to which compliance contributes to the superior (more rapid) therapeutic response from binocular therapies.