A Simple Quantitative Measure of Orbital Compliance

This study evaluates the reliability of a frequently used subjective measurement of orbital compliance (0-3 scale) and describes a simple, quantitative measure with excellent intra- and interrater reliability.

Two examiners performed both measurements on 100 orbits (50 consecutive patients) from the office of 1 oculoplastics surgeon. Each measurement was obtained at 2 different time points, 10 minutes apart. For the subjective measurement, the patient was asked to close their eyes, and the globe was displaced posteriorly with digital pressure until moderate resistance was felt. This was graded on a 0 to 3 scale. For the quantitative measurement (millimeter scale), the difference in axial displacement was measured using a Hertel exophthalmometer.

The subjective measurement (scale, 0-3) showed excellent test-retest reliability (average, 0.901) for both examiners at both time points and good interobserver reliability (average, 0.677). The quantitative measurement (millimeter scale) showed excellent test-retest reliability (average, 0.848) and very good interobserver reliability (average, 0.756).

This study shows that while both methods have both excellent test-retest reliability, the interobserver reliability is slightly higher with the quantitative measurement. This suggests that the described measurement of orbital compliance is both a reasonable alternative and possibly more accurate measurement without the steep learning curve.