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A randomised controlled trial of written information
  1. P Lempert
  1. Cornell University School of Veterinary Medicine, Ithaca, NY 14850, USA; eyechartplus{at}aol.com

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    Newsham's effort to inform parents of children with amblyopia about occlusion therapy is laudable but incomplete.1 Ethical considerations of informed consent require full disclosure of all aspects of the proposed treatment. The following points might be considered for inclusion.

    1. Occlusion therapy has never been scientifically validated with a randomised, controlled study.

    2. The dose/response relation has never been defined. Flynn et al stated that “Success was not related to the duration of occlusion therapy, type of occlusion used . . .”2 The variety of treatment protocols accentuates another dilemma “owing to our paucity of knowledge on the dose-effect relation—a situation one finds hard to imagine for any comparably established therapy outside ophthalmology. In other words we have no understanding of the dose-effect relation of occlusion in amblyopia therapy.”3

    3. The application of “greater levels of occlusion being prescribed for more severe amblyopia”1 is compromised by the observation “that success was related to . . . the depth of visual loss before treatment . . .”4

    4. The benefits of treatment are likely to deteriorate following cessation of patching.5

    5. Visual acuity improves as children become more mature, literate, and familiar with vision testing protocols.6 This is also true for amblyopic eyes. In amblyopic children between 3 and 7 years old without treatment visual acuity was shown to consistently improve in each older age group.7

    6. Both the occluded and the amblyopic eyes improve at the same rate during treatment.8

    7. Success in amblyopia treatment is usually defined as improvement by a minimum of three lines.9 Many of the successfully treated patients, by that criterion, will still not have normal vision at the end of presumably successful treatment. One quarter of treated patients with initial acuity better than 20/100 do not even achieve these limited goals.9 Therefore, the comments about achieving normal vision may raise expectations that will not be achieved.

    8. Occlusion therapy does have potential adverse effects beyond disruption of family and social life10 and interference with education.11

    9. Despite decades of occlusion therapy the prevalence of amblyopia in the adult population is similar to that of the school age population.12 Moreover, “the prevalence of unilateral amblyopia was not found to be statistically different by age group.”13 This suggests that long term benefits of conventional therapy are not demonstrated in demographic studies.

    Patients and their families should be provided with comprehensive information concerning proposed treatments. Physicians are obliged to make this information accurate and inclusive.2

    References

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