Comparing Methods of Quantifying Diplopia

Abstract

Purpose-Quantification of diplopia is important for describing severity of strabismus, measuring change over time and reporting surgical outcomes. The Cervical Range of Motion (CROM) method has been proposed as a simple, inexpensive alternative to the Goldmann perimeter for quantifying diplopia. The purpose of this study was to compare these two techniques and describe advantages and disadvantages. Design-Cohort study.Participants-Seventy six consecutive patients with binocular diplopia associated with any type of strabismus.Methods-Patients underwent diplopia assessment with the CROM and the Goldmann perimeter; diplopia was scored between 0 and 100 based on previously published scoring systems. Where CROM and Goldmann results were disparate by more than 20 points the medical record was reviewed independently by two clinicians to determine the most likely reason for the discrepancy.Main Outcome Measures-The two main outcomes were a measure of agreement between diplopia scores using the CROM and Goldmann using the Kappa test and the reasons for any disagreement between tests of greater than 20 points.Results-Overall agreement between the two tests was good (Intra-class correlation co-efficient= 0.65; 95% Confidence interval 0.50 to 0.77). In 49 out of 76 (64%) results using the CROM and Goldmann were within 20 points. Of the 27 (36%) showing a greater than 20 point discrepancy, 17 were worse using the Goldmann and 10 using the CROM. The most frequent reason for worse diplopia using the Goldmann was poorer ability to fuse or suppress in the Goldmann apparatus compared to the real world targets used in free space for the CROM. Worse diplopia using the CROM was most often due to the deviation being present for distance only. In some cases differences were due to the greater weighting of primary position using the current scoring system for the CROM.Conclusions-In the majority of cases the CROM and Goldmann provide equivalent measures of diplopia severity. However the Goldmann appears to overestimate diplopia in patients with fragile fusion or tenuous suppression, and underestimate diplopia in deviations present for distance only. The CROM method may be more representative of diplopia severity as experienced in everyday life.Quantifying diplopia is an important aspect of describing the severity of strabismus. Numerical quantification provides a means of assessing recovery, deterioration or change in response to treatment and is particularly useful when reporting treatment outcomes. Plotting a field of single binocular vision using the Goldmann perimeter 1-4 is currently considered the standard for quantifying diplopia, however Goldmann perimeters are expensive and are being replaced Correspondence and reprint requests to: Dr. Jonathan M. Holmes, Ophthalmology W7, Mayo Clinic, Rochester, MN 55905. Phone:

Comparison of a diplopia questionnaire to the Goldmann diplopia field

“…As we have described previously, 6 the choice of a 20-point difference was somewhat arbitrary, but was based on an evaluation of the proportion of discrepancies occurring at specific thresholds, that is 50-, 40-, 30-, 20-and 10-point differences. When there were more than a 20-point difference, details of the full eye examination in the medical record were reviewed independently by two clinicians (WEA and JMH), in order to determine the cause of the discrepancy.…”

“…The testing distance disparity between the Goldmann diplopia field and the Questionnaire is similar to the testing distance disparity demonstrated between the Goldmann diplopia field and the CROM method. 6 It appears that either the Diplopia Questionnaire or CROM method may better represent the diplopia experienced in sixth nerve palsy in everyday conditions.…”

“…As described as part of a previous study, 6 we then tested the patients with the Goldmann perimeter (Haag-Streit AG, Keoniz, Switzerland) using the III4e light target as described by Woodruff et al 1 and scored with the weighting template suggested by Sullivan et al, 2 which places an emphasis on primary position and reading. The test was performed by a trained examiner, and the target was moved from any area of single vision outward along meridians at intervals of 30 degrees.…”

“…We have previously reported a comparison of the Cervical Range of Motion (CROM) method to the Goldmann diplopia field in this same group of patients, and data obtained with the Goldmann diplopia field appeared in our previous manuscript. 6 Of the 76 patients in the original study, one patient did not complete the Diplopia Questionnaire for administrative reasons; therefore, 75 patients are included for analysis in the present report. …”

“…6 Of the 76 patients in the original study, one patient did not complete the Diplopia Questionnaire for administrative reasons; therefore, 75 patients are included for analysis in the present report.…”