Comparative study of 3 exophthalmometers and computed tomographic biometry

Area of Science:

• Ophthalmology
• Medical Imaging
• Biometry

Background:

• Accurate exophthalmometry is essential for diagnosing and managing orbital diseases, particularly Graves disease.
• Existing commercial exophthalmometers show considerable variation in their measurements.

Purpose of the Study:

• To compare the accuracy and reproducibility of three exophthalmometers (Luedde, Hertel, Mourits) against cerebral computed tomography (CT) scan biometry.
• To evaluate intraobserver and interobserver reliability for each instrument.

Main Methods:

• Sixty patients undergoing cerebral CT scans were included in the study.
• External prebicanthal segments (EPBCS), interorbital distance, and globe axial length were measured.
• Measurements from Luedde, Hertel, and Mourits exophthalmometers were compared to CT scan data.
• Intraclass correlation coefficient (ICC) and Bland and Altman plots assessed reproducibility.

Main Results:

• The Mourits exophthalmometer showed very good to good concordance with CT biometry.
• The Hertel exophthalmometer demonstrated moderate to good concordance.
• The Luedde ruler exhibited only moderate concordance with CT scan biometry.
• High intraobserver and interobserver reproducibility were noted, particularly for the Mourits exophthalmometer.

Conclusions:

• The 1-prism Mourits exophthalmometer offers superior accuracy compared to CT scan biometry.
• The Luedde and Hertel exophthalmometers provide lower and intermediate accuracy, respectively.
• The Mourits exophthalmometer is recommended for accurate exophthalmos measurement in clinical practice.