The best of both worlds, the small compact size of a Luedde and the ability to measure both eyes as the Hertel exophthalometer. The Dual Luedde Exophthalmometer is a low cost device to reliably measure the exophthalmos. It requires no special technique or skill. The Dual Luedde has been tested in a University Clinic setting and demonstrated results comparable to the Hertel Exophthalmometer. The purpose of any exophthalmometer is to measure the distance (exophthalmos) between the front most surface of the cornea compared to the external orbital canthus (orbital notch).
The normal range varies between 12 mm and 21 mm and a difference between the eyes greater than 2 mm is considered significant. In the treatment of diseases affecting the exophthalmos, the instrument is used to track the degree of forward (or backward) displacement of the eye. The Dual Luedde, like the Hertel, is not recommended where the orbit or eye socket has been damaged. In these cases the use of the Naugle (which indexes from the check bone and forehead) is more appropriate. Construction includes a sturdy metal backbone and two clear side scales that make measurement easy and quick. The head width adjustment includes a scale to permit repeatable setting of the distance from right to left orbital notch.