Objective survey of the prescription of occlusion therapy for amblyopia

To identify the variation within and consistency amongst orthoptists when prescribing occlusion therapy for amblyopia in an objective survey.A questionnaire was designed with five case examples of amblyopic children and distributed at annual meetings of orthoptists in The Netherlands and Germany. It was filled in simultaneously within 15 min in complete silence to avoid any exchange of opinions between orthoptists that would reduce variability. For each case the orthoptists were asked to give their prescription of hours or days of occlusion.The questionnaire was filled in by 177 Dutch orthoptists and 227 German orthoptists. Their prescriptions of occlusion therapy were classified into five main regimens: part-time; part-time not every day; full-time; also occluding the amblyopic eye; alternating; and no occlusion therapy. The variation was large: the standard deviation was half the average prescribed hours of occlusion for each regimen in each of the five cases. All orthoptists were assigned a rank number for each of the five cases depending on whether their prescription was above or below average. These five rank numbers were not consistently above or consistently below average value per case.The number of prescribed hours of occlusion varied widely per regimen per case. Orthoptists were not consistently strict or lenient in their prescription of occlusion therapy.