The Dose-Response Relationship with Intermittent Occlusion Therapy for Amblyopia

Abstract

Purpose : Using liquid crystal glasses, intermittent occlusion therapy (IO-therapy) has been introduced to treat amblyopia. Our previous study found that 4-hour IO-therapy is similarly effective compared to 2-hour patching in treating moderate amblyopia; however, we had no objective adherence measurement for these glasses, which limits understanding of the dose-repsonse for this treatment.(Wang et al, 2016). This study reports the pilot data of the dose-repsonse relationship of IO-therapy.

Methods : Eleven children (3-7 yrs) with unilateral amblyopia associated with strabismus and/or anisometropia were enrolled. Amblyopia was defined as an interocular visual acuity difference of at least 0.2 logMAR. Prior to IO-therapy, they wore optical correction glasses alone for 12 weeks. At enrollment, depending on severity of amblyopia, subjects were prescribed 4 or 12 hours of IO-therapy Glasses (Amblyz™, at 30-second opaque/transparent intervals). An inexpensive, commercially available waterproof microsensor was attached to the temple arm to monitor the hours of actual IO-therapy glasses-wear. Adherence was defined as the percentage of the hours of actual glasses-wear compared to the hours of prescribed. Daily adherence was calculated,and general adherence was the average of daily adherence. Patients were followed up at 12 weeks. The correlation of visual acuity change in the amblyopic eye and adherence was calculated.

Results : Visual acuity improved an average of 0.13±0.13 logMAR (range, -0.1 to 0.3 logMAR) at the 12-week follow-up visit. Adherence varied among and within individuals. General adherence averaged 48%±26% (range, 10% to 79%); total IO-therapy hours was averaged at 169 ± 94 hours (range, 54 to 284 hours). For this sample, there was no correlation between adherence with visual acuity change (R= -0.13, P=0.70); there was also no correlation between actual IO-therapy hours with visual acuity change (R= -0.23, P=0.50).

Conclusions : Visual acuity improvement with IO-therapy does not solely correlate with patient adherence. These preliminary results are limited with small sample and short-term follow-up.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.