Abstract
Purpose: :
To determine variability over time of three different methods of quantifying diplopia in adults with clinically stable strabismus: Diplopia Questionnaire (DQ), cervical range of motion (CROM) and Goldmann perimeter.
Methods: :
Consecutive assessments using the DQ, CROM, and Goldmann were compared in 15 adults with clinically stable paralytic or restrictive strabismus. Diplopia was scored from 0 points (pts) (no diplopia) to 100 pts (diplopia in all measured positions of gaze) for each method. Stability was defined as no historical or objective evidence of change, including ≤10 prism diopters change by prism cover tests in primary position over 2 consecutive exams (less than 1 year apart, range 5-364 days, median 78 days). The median diplopia score change was compared between the tests, and 95% limits of agreement, with associated 95% confidence intervals (CI), were calculated for each method.
Results: :
Changes ranged from -40 to 8 pts for the DQ, -60 to 16 pts for the CROM, and -68 to 18 pts for the Goldmann. Overall, there was no systematic bias toward increasing or decreasing scores over time and median changes were similar across tests (DQ 0 pts, CROM 0 pts, Goldmann -4 points, P>0.3 for all comparisons). 95% limits of agreement were numerically better for the DQ (24 pts 95% CI: 12 to 36 pts), followed by the CROM (44 pts 95% CI: 23 to 65 pts), followed by the Goldmann (50 pts 95% CI: 21 to 80 pts), but these comparisons were not statistically significant.
Conclusions: :
All three methods of quantifying diplopia had substantial variability over time in clinically stable patients. Possible sources of variability include small, clinically undetected changes in the underlying conditions over the short and long term, changes in patient adaptation to the condition, and true variability in the tests. Variability of measured diplopia over time needs to be considered in clinical practice and when designing and conducting clinical trials in strabismus.
Keywords: strabismus • strabismus: diagnosis and detection • esotropia and exotropia