Changes in ocular rigidity in endocrine exophthalmos.

(a) Hyperthyroid or Thyrotoxic Exophthalmos.-This accompanies Graves's disease and is, therefore, much more frequently seen in females than in males. In the majority of cases the exophthalmos is quite unobtrusive or there is merely an appearance of exophthalmos due to retraction of the upper lid. It is associated with a decreased frequency of blinking and a fixed stare. The majority of authors agree that these symptoms should be attributed to an increase in tone of the sympathetic system. The importance of the pituitary thyrotropic hormone in this clinical picture is not clear. Hyperthyroid exophthalmos is not complicated either by chemosis or by diplopia, but heterophoria and lack of convergence are often seen.