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Acupuncture for Amblyopia: Study Design Considerations

Acupuncture for Amblyopia: Study Design Considerations In the article by Dr Zhao and colleagues1 on acupuncture for amblyopia, it is unclear how long subjects actually wore optimal spectacles prior to randomization to patching or acupuncture. This issue is important because studies have shown that spectacles alone are a powerful treatment for amblyopia.2-4 The authors wrote that, “At a screening visit, protocol-specified spectacles were prescribed. . . The baseline examination was scheduled within 2 weeks of the screening visit. New spectacles were provided for all participants on the day of the baseline examination. . . With the participants wearing the new spectacles, VA (visual acuity) was measured in each eye. . . The better of the 2 VA scores was used as the baseline VA to assess eligibility. . . After eligibility was confirmed, participants were randomly assigned. . . Treatments were started within 2 days after randomization.” So it seems that subjects were given new spectacles and randomized within 2 days of receiving them. If so, this is inconsistent with the authors' statement that “Patients were eligible if they had worn optimal spectacles for at least 16 weeks prior to enrollment,” and “The spectacles should have been worn until VA was stabilized.” The spectacles should have been or were actually worn for at least 16 weeks? If many subjects were randomized before visual acuity stopped improving with spectacles, I am not surprised that both patching and acupuncture groups had robust improvement. In an equivalence study (unlike a superiority study), factors such as new spectacles or a recent change in spectacles that predispose to improvement in both groups will bias toward supporting the study hypothesis (in this case, equivalence between patching and acupuncture). In addition, I am concerned that the disparate frequency of contact with office staff may have affected the primary outcome (visual acuity) in this study. During the 15 weeks between baseline and the primary outcome measure, the patching group had 3 total office visits, whereas the acupuncture group had 5 visits per week, or 75 total visits. Frequent office visits can increase a child's comfort level when performing tests such as outcome visual acuity, and it can also lead to better compliance with concurrent study treatments of spectacles wear and near activities. Finally, I think that the felt patches prescribed for the patching group were not the best choice for this trial. The fact that “No parent reported at any visit that their child had performed less than 2 hours of patching at any time” does not mean that the child did not spend a good deal of time looking over or around the both the patch and spectacles. Back to top Article Information Correspondence: Dr Wallace, Duke Eye Center, Box 3802, Durham, NC 27710 (david.wallace@duke.edu). Financial Disclosure: Dr Wallace reports receiving funding from the National Eye Institute in his role as Vice Chair of the Pediatric Eye disease Investigator Group, which performs randomized trials in amblyopia. References 1. Zhao J, Lam DS, Chen LJ, et al. Randomized controlled trial of patching vs acupuncture for anisometropic amblyopia in children aged 7 to 12 years. Arch Ophthalmol. 2010;128(12):1510-151721149771PubMedGoogle ScholarCrossref 2. Steele AL, Bradfield YS, Kushner BJ, France TD, Struck MC, Gangnon RE. Successful treatment of anisometropic amblyopia with spectacles alone. J AAPOS. 2006;10(1):37-4316527678PubMedGoogle ScholarCrossref 3. Cotter SA, Edwards AR, Wallace DK, et al; Pediatric Eye Disease Investigator Group. Treatment of anisometropic amblyopia in children with refractive correction. Ophthalmology. 2006;113(6):895-90316751032PubMedGoogle ScholarCrossref 4. Chen PL, Chen JT, Tai MC, Fu JJ, Chang CC, Lu DW. Anisometropic amblyopia treated with spectacle correction alone: possible factors predicting success and time to start patching. Am J Ophthalmol. 2007;143(1):54-6017113556PubMedGoogle ScholarCrossref http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of Ophthalmology American Medical Association

Acupuncture for Amblyopia: Study Design Considerations

Wallace, David K.
Archives of Ophthalmology , Volume 129 (9) – Sep 12, 2011
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References (4)

Publisher
American Medical Association
Copyright
Copyright © 2011 American Medical Association. All Rights Reserved.
ISSN
0003-9950
eISSN
1538-3687
DOI
10.1001/archophthalmol.2011.239
Publisher site
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Abstract

In the article by Dr Zhao and colleagues1 on acupuncture for amblyopia, it is unclear how long subjects actually wore optimal spectacles prior to randomization to patching or acupuncture. This issue is important because studies have shown that spectacles alone are a powerful treatment for amblyopia.2-4 The authors wrote that, “At a screening visit, protocol-specified spectacles were prescribed. . . The baseline examination was scheduled within 2 weeks of the screening visit. New spectacles were provided for all participants on the day of the baseline examination. . . With the participants wearing the new spectacles, VA (visual acuity) was measured in each eye. . . The better of the 2 VA scores was used as the baseline VA to assess eligibility. . . After eligibility was confirmed, participants were randomly assigned. . . Treatments were started within 2 days after randomization.” So it seems that subjects were given new spectacles and randomized within 2 days of receiving them. If so, this is inconsistent with the authors' statement that “Patients were eligible if they had worn optimal spectacles for at least 16 weeks prior to enrollment,” and “The spectacles should have been worn until VA was stabilized.” The spectacles should have been or were actually worn for at least 16 weeks? If many subjects were randomized before visual acuity stopped improving with spectacles, I am not surprised that both patching and acupuncture groups had robust improvement. In an equivalence study (unlike a superiority study), factors such as new spectacles or a recent change in spectacles that predispose to improvement in both groups will bias toward supporting the study hypothesis (in this case, equivalence between patching and acupuncture). In addition, I am concerned that the disparate frequency of contact with office staff may have affected the primary outcome (visual acuity) in this study. During the 15 weeks between baseline and the primary outcome measure, the patching group had 3 total office visits, whereas the acupuncture group had 5 visits per week, or 75 total visits. Frequent office visits can increase a child's comfort level when performing tests such as outcome visual acuity, and it can also lead to better compliance with concurrent study treatments of spectacles wear and near activities. Finally, I think that the felt patches prescribed for the patching group were not the best choice for this trial. The fact that “No parent reported at any visit that their child had performed less than 2 hours of patching at any time” does not mean that the child did not spend a good deal of time looking over or around the both the patch and spectacles. Back to top Article Information Correspondence: Dr Wallace, Duke Eye Center, Box 3802, Durham, NC 27710 (david.wallace@duke.edu). Financial Disclosure: Dr Wallace reports receiving funding from the National Eye Institute in his role as Vice Chair of the Pediatric Eye disease Investigator Group, which performs randomized trials in amblyopia. References 1. Zhao J, Lam DS, Chen LJ, et al. Randomized controlled trial of patching vs acupuncture for anisometropic amblyopia in children aged 7 to 12 years. Arch Ophthalmol. 2010;128(12):1510-151721149771PubMedGoogle ScholarCrossref 2. Steele AL, Bradfield YS, Kushner BJ, France TD, Struck MC, Gangnon RE. Successful treatment of anisometropic amblyopia with spectacles alone. J AAPOS. 2006;10(1):37-4316527678PubMedGoogle ScholarCrossref 3. Cotter SA, Edwards AR, Wallace DK, et al; Pediatric Eye Disease Investigator Group. Treatment of anisometropic amblyopia in children with refractive correction. Ophthalmology. 2006;113(6):895-90316751032PubMedGoogle ScholarCrossref 4. Chen PL, Chen JT, Tai MC, Fu JJ, Chang CC, Lu DW. Anisometropic amblyopia treated with spectacle correction alone: possible factors predicting success and time to start patching. Am J Ophthalmol. 2007;143(1):54-6017113556PubMedGoogle ScholarCrossref

Journal

Archives of Ophthalmology – American Medical Association

Published: Sep 12, 2011

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