Electronically Recorded Occlusion Treatment in Amblyopes Older than 7 Years: Acuity Gain after more than 4 Months of Treatment?

Background: According to the ROTAS study most of the improvement in visual acuity (VA) during amblyopia therapy of children aged 3 to 8 years occurs during the first 6 to 8 weeks [1]. Sattler reported a VA gain in 11-year olds even during the second year of treatment [2]. So far there are no standards concerning the intensity and duration of the treatment of patients older than 7 years of age. After a report on electronic monitoring of occlusion treatment in patients aged 7 to 16 years for 4 months [3], we now analyse whether this age group benefits from a longer-lasting treatment. Materials and Methods: In this pilot study the progression of VA was analysed in 11 patients (age range 7.18 to 15.76 years; median 11.42 years) during 12 months of occlusion therapy (types of amblyopia: 5 anisometropic, 1 strabismic, 5 combined). The daily occlusion times were recorded using the occlusion dose monitor (ODM) [4]. At the beginning of treatment the prescription of the occlusion regime (median) was 6 h/d (range 4 to 7 h/d), the (decimal) VA0.2 (range 0.02 to 0.63) for single and 0.16 (range 0.02 to 0.8) for crowded optotypes. Results: The recorded occlusion time (median) was 4.4 h/d during the 12 months of treatment, the VA gain (median) was 0.4 log units for single (range 0.2 to 0.7 log units) and 0.3 for crowded optotypes (range -0.1 to 0.6). During the period of 4 to 12 months of treatment (received occlusion 4.12 h/d) the VA gain was 0.1 log units for single and for crowded optotypes. The maximum VA gain during the interval of 4 to 12 months of treatment was 0.2 log units, both single and crowded. The interocular difference for crowded VA (median) decreased from 0.9 to 0.6 log units during treatment, however only one patient achieved an interocular difference of <0.2 log units. Conclusion: The patients presented here were able to integrate daily occlusion lasting several hours and the electronic monitoring of occlusion treatment into their daily routine over a period of 12 months. During this period the VA of all included types of amblyopia improved significantly, both from a clinical and statistical point of view. Further long-term studies using ODMs with larger groups of patients may identify factors for success of treatment, reveal the long-term stability of the improvement and contribute to a standardised treatment in this age group