Background:To date,compliance to atropine penalization in amblyopic children has only been assessed through self-report.The goal of this pilot study is to measure compliance to atropine penalization objectively.Methods:Seven amblyopic children(3-8 years;20/40-20/125 in the amblyopic eye) were enrolled.None had been treated with atropine previously.Children were prescribed either a twice per week or daily atropine regimen by their physicians.Compliance was defined as the percentage of days in which the atropine eye drop was taken compared to the number of doses prescribed.We used medication event monitoring system(MEMS) caps to objectively measure compliance.The MEMS caps are designed to electronically record the time and date when the bottle is opened.The parents of the children were provided a calendar log to subjectively report compliance.Participants were scheduled for return visits at 4 and 12 weeks.Weekly compliance was analyzed.Results:At 4 weeks,objective compliance averaged 88%(range,57-100%),while subjective compliance was 98%(range,90-100%).The actual dose in grams and visual acuity(VA) response relationship(r=0.79,P=0.03) was significantly better than the relationship between regimen and response(r=0.41,P>0.05),or the relationship between actual dose in drops and response(r=0.52,P>0.05).Conclusions:Objective compliance to atropine penalization instructions can be monitored with MEMS,which may facilitate our understanding of the dose-response relationship.Objective compliance with atropine penalization decreases over time and varies with regimen.On average,subjective parental reporting of compliance is overestimated. Background: To date, compliance to atropine penalization inmblymbly children has only been assessed through self-report. The goal of this pilot study is to measure compliance to atropine penalization objectively. Methods: Sevenmblymbly penalis (3-8 years; 20/40 -20/125 in the amblyopic eye) were enrolled. None had been treated with atropine previously. Childrens were prescribed either a twice per week or daily atropine regimen by their physicians. Compliance was defined as the percentage of days in which the atropine eye drop The lenses caps are designed to electronically record the time and date when the bottle is opened. The parents of the children were provided a calendar log to subjectively report compliance. Participants were scheduled for return visits at 4 and 12 weeks. Weekly compliance was analyzed. Results: At 4 weeks, objective compliance averaged 88% (range, 57-100%) while subjective compliance was 98% (range, 90-100%). The actual dose in grams and visual acuity (VA) response relationship (r = 0.79, P = 0.03) was significantly better than the relationship between regimen and response (r = 0.41, P> 0.05), or the relationship between actual dose in drops and response (r = 0.52, P> 0.05) .Conclusions: Objective compliance to atropine penalization instructions can be monitored with MEMS, which may facilitate our understanding of the dose-response relationship. Objective judgmental with atropine penalization decreases over time and varies with regimen .On average, subjective parental reporting of compliance is overestimated.