opia. Suppuration usually ensues, and the pus burrows in
every direction, and may ultimately point through the eyelids or
conjunctiva. Sometimes the infection spreads to the meninges, and to
the ophthalmic vein, and the phlebitis may then extend to the
cavernous sinus. The eyeball may be infected and destructive
panophthalmitis result. The prognosis therefore is always grave.

The _treatment_ consists in making one or more incisions into the
cellular tissue for the purpose of removing the pus and establishing
drainage. A narrow bistoury is passed in parallel to the wall of the
orbit, care being taken to avoid injuring the globe. When possible,
the incision should be made through the reflection of the conjunctiva,
but in some cases efficient drainage can only be established
by incising through the lid. When the eye is destroyed by
panophthalmitis, the propriety of eviscerating or enucleating it will
have to be considered.

#Tumours of the Orbit.#--Tumours may originate in the orbit or may
invade it by spreading from adjacent cavities. Those which originate
in the orbit may be solid or cystic. Of the solid tumours the glioma
and the sarcoma are the most common, and when they originate in the
pigmented structures of the globe they present the characters of
melanotic growths. Primary carcinoma begins in the lachrymal gland.
Osteoma--usually the ivory variety--may originate in the wall of the
orbit, or may spread from the adjacent sinuses.

_Clinical Features._--In children, the tumour is usually a glioma, and
it is frequently bilateral. It generally occurs before the age of
four, is associated with increased intra-ocular tension, protrusion of
the eyeball, and dilatation of the pupil, and soon produces blindness.
The tumour fungates and bleeds, and rapidly invades adjacent
structures and spreads along the optic nerve to the brain. It is
highly malignant, and recurrence usually takes place, even when the
tumour is removed early.

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, oedematous, and dusky. The eye is
seldom pushed directly