To the Editor.
—The randomized multicenter clinical trial described in the September 1990 issue of the Archives was designed to determine the efficacy of prism adaptation (PA) in the surgical management of acquired esotropia.1 In randomized studies, the control population and the experimental population are evaluated before surgery on an equal basis to avoid observer bias. However, in this study, did the PAR/PS patients (prism adaptation responders undergoing surgery for their deviation determined by Fresnel prism) undergo more measurements of their ocular deviation than the non-PA/ES patients (patients who did not have prism adaptation and who underwent surgery for their deviation determined by prism cover test)? If so, does this bias the results? Could this also explain the resulting difference between PAR/ES patients (prism adaptation responders who underwent surgery for their deviation determined by prism cover test) and PAR/PS patients? Both had PA; however, less surgery was performed on
Giangiacomo J. Efficacy of Prism Adaptation in the Surgical Management of Acquired Esotropia. Arch Ophthalmol. 1991;109(6):765. doi:10.1001/archopht.1991.01080060019002