Methods for quantifying diplopia

Abstract

Abstract Purpose: Methods for quantifying diplopia include 1) the Goldmann diplopia field, 2) the Cervical Range of Motion (CROM) method, evaluating 10 specific positions of gaze and 3) a Diplopia Questionnaire addressing 7 positions of gaze (rating diplopia as always, sometimes or never). We investigated how patients’ subjective perception of the severity of their diplopia (percent impact) related to scores obtained using each of these methods. Methods: 28 patients with acquired binocular diplopia due to strabismus were asked to rate the percent impact of their diplopia, based on all daily activities. Diplopia was also quantified using the Goldmann perimeter, CROM method and Diplopia Questionnaire. Scores were scaled from 0 to 100, where 0 was no diplopia and 100 was diplopia in all measured positions. Correlations between percent impact and diplopia measures were assessed using intra‐class correlation coefficients (ICC) and mean values compared using t‐tests. Results: Across all patients, the mean self‐rated percent impact was 40% (range 0 to 100%). Mean scores using the CROM and Questionnaire were similar to percent impact (39% and 38% respectively), whereas Goldmann scores significantly overestimated severity when compared to perceived impact (51%, p<0.05). Percent impact was most closely correlated to the Questionnaire score (ICC=0.75). The most frequent reason for a higher Goldmann diplopia score was scoring of diplopia beyond 30 degrees. Conclusions: Quantifying diplopia using the CROM method and Diplopia Questionnaire better represents the perceived impact of patients’ diplopia than scores obtained on the Goldmann perimeter. The CROM method and Diplopia Questionnaire may prove useful instruments for clinical evaluation of diplopic patients and in future clinical trials.