Electronic recording of occlusion treatment for amblyopia: potential of the new technology

Approximately one third of all amblyopic eyes do not reach visual acuity of 20/40 in spite of occlusion therapy. One of the reasons is a lack of adherence to therapy, which, however, could not be quantified in the past. Experience with new devices (occlusion dose monitors, ODMs) for electronic recording of occlusion has recently been reported. The aim of the present study was to evaluate the potential of the ODMs developed in The Netherlands. Various features were tested, including the reliability of the ODM recordings compared to diaries, two ODMs used simultaneously on one patch, the influence of the ambient temperature, and the specificity of the recording pattern for measurements on the eye.

The ODMs were taped to the outside of the standard occlusion patch and measured the temperature difference between their front and back surfaces. Members of the research group and the families of two patients kept occlusion diaries while using the ODMs. Recorded and written occlusion periods were compared. Measurements were carried out under various conditions: patch with one ODM tightly on the eye or detached (allowing peeping); ODMs taped to various parts of the body; two ODMs simultaneously on one patch; variation of room temperature.

There was good correspondence between the occlusion times recorded by the ODMs and those from the diaries, as well as between the recordings of two ODMs used simultaneously on one patch. High ambient temperatures (33 degrees C to 37 degrees C) prevented reliable ODM measurements. Measurements on other parts of the body were misclassified with probabilities between P=0.099 and P=0.325 as measurements with the patch tightly on the eye.

In spite of some technical limitations, the ODMs provide a chance for reliable assessment of compliance and therefore objective information on dose-response function for occlusion therapy. This will lead to a more evidence-based treatment for amblyopia.