Measuring eye movements in Graves ophthalmopathy

Abstract

Background: The current grading of class IV (extraocular muscle involvement) of the NO SPECS classification for Graves ophthalmopathy is subjective and, in practice, virtually limited to three grades (grade c rarely occurs). The subjectiveness results in a high degree of observer disagreement, as illustrated by kappa values of 0.48 to 0.64 for the agreement between the authors in grading of class IV changes in 13 patients.

Methods: The authors investigated the significance of a quantitative approach in assessing eye motility and modified a hand perimeter to measure the monocular eye movements in degrees.

Results: The mean maximal excursions in the four main directions of gaze, obtained with this device in 40 healthy control subjects (5 men and 5 women from each decade between 20 and 60 years of age), were as follows: elevation = 34 degrees, depression = 58 degrees, adduction = 48 degrees, and abduction = 46 degrees. The ductions showed an age-related decline. The intraobserver and interobserver variations were assessed in 12 and 18 patients with Graves ophthalmopathy, respectively, by calculating the coefficients of repeatability, which varied from 5 degrees to 8 degrees. The authors compared the current grading of NO SPECS class IV with quantitative measurements of elevation in 11 patients by calculating the kappa values for agreement. These were found to be 0.57 and 0.80, respectively.

Conclusions: The quantitative measurement of eye movements with a modified perimeter appears to be precise and reproducible. In addition, it should replace the current grading of the extraocular muscle movements of Graves ophthalmopathy patients in the NO SPECS classification, which is less reliable, as evidenced by a higher degree of observer disagreement.