In adults melanotic sarcoma is most common. It occurs between the ages of forty and sixty, and is almost always unilateral; and while it shows little tendency to invade the brain, the adjacent lymph glands are early infected, and death usually results from dissemination.
In all varieties of intra-orbital tumour exophthalmos is a prominent feature ([Figs. 238], [239]), and when the protrusion of the eyeball is marked the lids become swollen, œdematous, and dusky. The eye is seldom pushed directly forward except when the tumour is growing in the optic nerve or its sheath. When the tumour is solid, the eye cannot be pressed back into the orbit, but in cystic tumours it may to some extent. The movements of the eyeball are restricted in a varying degree, and ptosis often results from paralysis of the levator palpebræ superioris. In almost all cases there is also more or less visual disturbance. The cornea being unduly exposed is liable to become inflamed, or even ulcerated. Pain is a variable symptom; when present, it usually radiates along the branches of the first and second divisions of the trigeminal nerve. Tenderness on pressure is not always present. It is comparatively uncommon for a tumour of the orbit to invade the globe directly.
Fig. 238.—Sarcoma of Orbit, causing exophthalmos and downward displacement of the eye, and projecting in temporal region.
Fig. 239.—Sarcoma of Eyelid in a child.
(Mr. D. M. Greig's case.)
Treatment.—When practicable, removal of the tumour is the only method of treatment, and in malignant tumours it is often necessary to sacrifice the eye to ensure complete removal. When the tumour has invaded the orbit secondarily, its removal may be impossible, but it may be necessary to remove the eye for the relief of pain.
The orbital dermoid usually occurs at the lateral end of the supra-orbital ridge ([Fig. 240]). A less common situation is the anterior part of the orbit, near the nasal wall, and this variety, from its position and from the fact that it is usually met with in children, is liable to be confused with orbital meningocele or encephalocele. Treatment consists in its removal by careful dissection, and this can usually be done under local anæsthesia.