Definition of successful outcomes after surgery for each type of strabismus: a Delphi study

The Delphi process has been widely used to delineate guidelines for the treatment of disorders for which there is little or no evidence in the published literature. The purpose of this study was to use the Delphi process to identify areas of consensus and disagreement on the definition of success after surgery for each type of strabismus.

Two rounds of electronic questionnaires were sent to 28 members of the Strabismus Success Definition Delphi Study Group. For the first round, responses to 70 questions were captured as agree (= 1) and disagree (= 2). For round 2, a total of 89 questions were captured on a Likert scale ranging from 1 (strongly disagree) to 7 (strongly agree). Consensus was determined a priori at 85%.

In both the first and second rounds, inter-rater agreement of 85% consensus was reached for only 20% of questions. Intra-rater agreement per question was low, with κ values ranging from -0.11 to 0.62. Intra-rater agreement was also low among themes, ranging from poor to fair agreement: κ = 0.25 for motor, κ = 0.28 for sensory, and κ = 0.35 for follow-up.

This study highlights consensus areas that could be considered by researchers in designing studies and identifies areas where lack of consensus indicates that further research is needed.