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Use of a grading system in the evaluation of complications in a randomised controlled trial on cataract surgery. Oxford Cataract Treatment and Evaluation Team (OCTET).


A randomised controlled trial in progress for more than five years assessed 333 eyes by three methods of cataract surgery. These were (A) intracapsular extraction and contact lens usage; (B) intracapsular extraction and implantation of an iris supported lens (Federov I); and (C) extracapsular extraction and implantation of an iridocapsular lens (Binkhorst 2-loop). This paper reports the use of a weighting scale for rank scoring complications which are dissimilar or are mutually exclusive (for example, capsular versus contact lens problems) to allow the use of non-parametric statistics for comparing disparate features. Thus we found that group B did significantly worse in terms of the number and severity of postoperative complications, a trend in accordance with visual results. This method may serve as a useful model for similar studies.

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