Effect of exophthalmometer design on its accuracy.
PURPOSE: To investigate the effect of the design of different exophthalmometers on their measurement accuracy. METHODS: Eight different exophthalmometers were tested with a specially developed calibrator by experienced orbital surgeons. RESULTS: Exophthalmometers with one mirror and a straight footplate were found to be more accurate than others. One-mirror exophthalmometers were less accurate when assessing low (< or =12 mm) and high (> or =23 mm) exophthalmometric values. CONCLUSIONS: The design of an exophthalmometer affects its accuracy.