Clinical exophthalmometry: a comparative study of the Luedde and Hertel exophthalmometers

Abstract

Exophthalmometry, the quantitative assessment of the position of the globe in the orbit, is a clinically useful measurement. The purpose of this study was to examine the performance of a simple exophthalmometer that would lend itself to accurate and convenient use in clinical practice. In this study, two observers independently performed exophthalmometry on 100 eyes using the Hertel and Luedde instruments. The results were compared between instruments and between observers. There was no statistically or clinically significant difference between measurements taken with the Luedde as compared with the Hertel instrument. The Luedde exophthalmometer has a number of advantages over the Hertel exophthalmometer, and represents a simple, inexpensive and equally reliable means of evaluating clinically the anteroposterior position of the eye in the orbit.Key words: Exophthalmometry, exophthalmos, Hertel, Luedde, proptometry, proptosis.Exophthalmometry may be defined as the measurement of the distance between two parallel planes, one tangent to the apex of the cornea with the eye in the primary position, the other passing through the lateral orbital margin.It provides a quantitative clinical measure of the position of the eye in the orbit. Absolute exophthalmometry depends on radiological assessment, the result being compared with a normal value. This method is not clinically applicable because of the many variables which include orbital linear dimensions and volume. In serial exophthalmometry, the clinical measurements are compared over time and in relative exophthalmometry, the results on the two sides are compared.Exophthalmometry provides clinical measurement of proptosis or enophthalmos, which is of value in evaluating patients with orbital disease or abnormal globe size. Apparent proptosis, such as lid retraction, can be distinguished from true proptosis. Quantitative assessment is particularly valuable in serial measurements, for example while monitoring the course of proptosis in management of thyroid orbital disease. Exophthalmometry, as a parameter to assess orbital disease, together with clinical examination, visual field assessment and organ imaging techniques facilitates management and decisionmaking. With this in mind, it is important that any instrument measuring proptosis be portable, readily available, and quick to use. Any result must be reproducible between observers and over time.The terms exophthalmos and proptosis are both derived from Greek, and mean 'protrusion of the eye'. To many clinicians, exophthalmos may have implications of thyroid orbital disease. Although exophthalmometry is currently stan-

Reliability of exophthalmos measurement and the exophthalmometry value distribution in a healthy Dutch population and in Graves' patients. An exploratory study

“…Comparative studies of different exophthalmometers show that other exophthalmometers have their advantages. 7,8 We believe that these studies should be encouraged and that international (orbital) societies should select an exophthalmometer of choice that will be used world-wide. Only with such an instrument plus a clear description of the race, gender, age and disease of the individuals involved can exophthalmometer readings be internationally compared.…”

The Effect of Age, Gender, Refractive Status and Axial Length on the Measurements of Hertel Exophthalmometry

“…There are various devices for exophthalmometric purposes; however, Hertel exophthalmometry is the most commonly used device [7]. Although the normal limits of protrusion of the human eye are accepted to be between 10 and 21mm, exophthalmometric values have been shown to vary with ethnicity, age, gender, height, weight, body mass index (BMI), orbital parameters, refraction and axial length (AL) of the eye [1, 4, 8-18].…”

Exophthalmometric Values in a Normal Turkish Population Living in the Northeastern Part of Turkey

“…Each of these devices evaluates protrusion by means of lateral orbital margins. Currently, Hertel exophthalmometry is the most commonly used device (1). Hertel exophthalmometry measures the distance between the lateral orbital rim and the apex of cornea perpendicular to the frontal plane.…”

“…We attempted to determine the normal values of proptosis for healthy individuals living in the Erzurum county in the northeastern part of Turkey. 1 …”