These lesions are frequently the result of blows and of penetrating injuries, as well as of syphilis. Moreover, motility of the iris is so essential to the normal function of the eye that where it may possibly be effected the surgeon should protect against those adhesions between the iris and the lens or cornea, which are very likely to occur, by instillation of a sufficiently strong solution of atropine, a ¹⁄₂ to 1 per cent. solution being usually sufficient for this purpose. These adhesions are referred to as synechiæ, and are anterior when the iris becomes affixed to the cornea, or posterior when affixed to the lens. They occur easily after minute punctures of the cornea, the result being a limited mobility or a dislocation of the pupil, along with opacity of the cornea, all of which work to the detriment of vision.
The iris is so visible that the mechanism of an exudate on or in it can be observed almost from beginning to end when it occurs in the form of iritis. Occasionally an exudate will merge into an actual collection of pus which will gradually fill up the anterior chamber, and which is then spoken of as hypopyon. Under the most favorable circumstances a disappearance of this pus by absorption may be noted. It may prove destructive or may necessitate evacuation.
The iris and the ciliary body are intimately connected, and inflammation beginning in one point may easily spread to and involve other tissues. These structures with the choroid constitute the so-called uveal tract, and when they participate in inflammation it is called uveitis.
The symptoms of iritis consist of pain, lacrymation, photophobia, which is often intense; increasing turbidity of the aqueous humor, as well as of the cornea, by which vision is impaired; visible discoloration; irregularity and sluggishness in movements of the iris, and circumcorneal injection. A congestion which assumes an annular form about the cornea and does not involve the conjunctival sac indicates trouble in the ciliary region, while a true conjunctivitis is limited only by the extent of the membrane itself.
Iritis due to syphilis, whether assuming the plastic or the gummatous form, requires the most active antisyphilitic medication, in addition to local treatment. The non-specific and traumatic forms need absolute rest in a dark room, with cold applications about the eye and the free use of atropine, to completely dilate the pupil and prevent the formation of synechiæ.
THE CORNEA.
The cornea being the most exposed part of the eyeball will be frequently subjected to minor or serious injury in connection with violence to the orbital region. It is an exceedingly sensitive membrane, whose reflex excitability is heightened by the presence of a small foreign body, this accident being one of frequent occurrence. It is a lesson in neurophysiology to watch the relatively local and general disturbances which the presence of a minute speck of foreign material embedded in the cornea may cause. Every extraneous body should be removed at once, the procedure being now facilitated by the local use of cocaine, for any abrasion or serious injury of the cornea occurring in surgical cases offers a possible source of infection to the deeper ocular structures. Careful attention should be given to the use of antiseptics of suitable strength in the conjunctival sac, whenever this region is involved. This statement cannot be made too positive. There is danger both to the cornea and to the iris in perforating ulcer or traumatism of the cornea, and there is as much occasion for the use of atropine in these instances as in those pertaining to the iris proper. To the protrusion of the cornea, which is produced by weakening of its structure and tension from within, is given the name staphyloma. It is frequently combined with adhesions of the iris and dislocation of the pupil. It constitutes not only a cosmetic disfigurement, but a serious impediment to vision.
PLATE XLV
FIG. 1
