Interinstrument Variability in Hertel-Type Exophthalmometers

Abstract

It is already considered good practice to minimize interobserver error by recording the make of exophthalmometer used. This small study also suggests that the same instrument should be used for each examination to minimize error caused by variation between instruments of the same make. Variation of 1.5 to 2.0 mm could affect patient treatment when a difference in measurement of 2 mm is regarded as significant during serial or relative exophthalmometry.