Additional clinical sign of "unilateral" endocrine exophthalamos.

There may be difficulties in the diagnosis of unilateral endocrine exophthalmos particularly in the differential diagnosis from orbital tumour. It is the purpose of this communication to show that endocrine ophthalmopathy is always bilateral, although its exophthalmic component is frequently unilateral in its early stages. This observation could be the basis of differential diagnosis between "unilateral endocrine exophthalmos" and retrobulbar tumour. To facilitate differential diagnosis, use is made of a phenomenon already reported by Birch-Hirschfeld (1930) that in all normal subjects there is a difference in the exophthalmometric readings in the upright and recumbent position. In all normal subjects the globe sinks back when the patient is recumbent, and the exophthalmometric reading is reduced by I to 3 mm. Hauer (I956) has shown that this postural difference is absent in both eyes in cases of endocrine ophthalmopathy and that this is independent of the presence or absence of a visible exophthalmos. Thus, the presence of the physiological postural difference in the opposite side in a case of orbital tumour and its absence in a case of unilateral endocrine exophthalmos may be used as the basis in the differential diagnosis between the two conditions. This is illustrated in the following cases, where the assumption that endocrine exophthalmos is, even in its initial unilateral phase as judged by conventional methods, a bilateral condition, while orbital tumours are usually unilateral, assisted the correct diagnosis.