Abstract
Purpose: :
Refractive adaption has become an important part of amblyopia treatment allowing time for patients to adapt to their refractive correction before beginning occlusion therapy. However, it is unknown whether the outcome of refractive adaptation is dictated by compliance to glasses wear since compliance has never been objectively monitored. The dose-response relationship between visual acuity and compliance has also never been established. We have explored this relationship using electronic dose monitors of glasses wearing in newly diagnosed amblyopes.
Methods: :
Twenty-five amblyopes with no previous treatment were recruited to the study, twelve anisometropes, nine mixed and four strabismic amblyopes. Patients were asked to wear their glasses full time for 18 weeks during which compliance was monitored using an electronic dose monitors. Visual acuity was measured at the beginning of the study and further assessed every six weeks. After refractive adaptation patients began occlusion treatment during which both glasses and occlusion compliance was monitored.
Results: :
Compliance for refractive correction ranged from 19.1% to 95.4% of waking hours, with 23% of patients achieving less than 50% compliance (equivalent to 6.5hrs per day) (mean compliance was 67.6%). There was a highly significant dose response relationship between hours of glasses worn per day and visual acuity (r=0.76, p=0.0001). The linear trend in the data indicated that optimal improvement in visual acuity (≥12 hours of glasses wearing per day) was equivalent to a 42% improvement in visual acuity. Four hours of glasses wearing a day produced no improvement in visual acuity.
Conclusions: :
Evidence from this study reveal compliance to glasses wear during refractive adaptation is far from optimal. The dose response function indicated that best expected improvement in visual acuity after 18 weeks refractive adaptation is only 42% even with full time glasses wear. This poses the question as to the benefits provided by extended refractive adaptation. A number of previous studies have highlighted the importance of compliance in patching therapy. This is the first study to provide evidence that compliance to refractive correction for amblyopia treatment is also a significant issue which requires further exploration.
Clinical Trial: :
http://www.isrctn.org ISRCTN05346737
Keywords: amblyopia • visual acuity • strabismus: treatment