Exophthalmos is the sign of orbital disease of prime importance. The amount of proptosis may vary considerably in various types of diseases. It may be minimal where the amount of exophthalmos is questionable, or it may be marked so that an unusual appearance of proptosis is present. At times cases have been reported where the eyeball has been displaced anterior to the lids. The determination of exophthalmos may be made by inspection or may be made by measurement.
In considering the differential diagnosis, the question of bilateral and unilateral exophthalmos is important, and it is also important to observe the rate of development of the exophthalmos. Measurement of. the exophthalmos may be done by rather simple methods, such as using a millimeter rule and estimating the amount of proptosis of the anterior portion of the cornea beyond the level of the external angular rim of the orbit. However, the Hertle