Exophthalmometer

An Exophthalmometer is an instrument used for measuring the degree of forward displacement of the eye in exophthalmos. The device allows measurement of the forward distance of the lateral orbital rim to the front of the cornea. Exophthalmometers can also identify enophthalmos (retraction of the eye into the orbit), a sign of blow-out fracture or certain neoplasms. An Exophthalmometer is an instrument used for measuring the degree of forward displacement of the eye in exophthalmos. The device allows measurement of the forward distance of the lateral orbital rim to the front of the cornea. Exophthalmometers can also identify enophthalmos (retraction of the eye into the orbit), a sign of blow-out fracture or certain neoplasms. There are several types of exophthalmometers: Hertel and Luedde exophthalmometers measure the distance of the corneal apex from the level of the lateral orbital rim, while Naugle exophthalmometers measure the relative difference between each eye. The normal range is 12–21 mm. Upper normal limit for people of African origin is a little higher, about 23–24 mm.