Part 37 (1/2)

(ii) To evacuate pus from the anterior chamber following metastatic infection.

(iii) To evacuate the anterior chamber in bad corneal ulceration, especially when a.s.sociated with hypopyon and tension.

(iv) To examine the aqueous for organisms in cases of cyc.l.i.tis following operation or of metastatic origin.

(v) To evacuate soft lens matter (see p. 194).

The operation is usually performed through an incision directly behind the limbus. In the case of corneal ulceration it is sometimes performed by dividing the base of the ulcer with a Graefe's knife (Samisch's section). When collecting the aqueous for bacteriological examination, a sterile hollow needle with a point similar to a discission needle, attached to a hypodermic syringe, should be pa.s.sed into the anterior chamber at the limbus and the fluid withdrawn into the syringe by an a.s.sistant (Fig. 123). The spot through which the needle is pa.s.sed is first touched with the electro-cautery to ensure asepsis.

=Instruments.= Speculum, fixation forceps, bent broad needle, iris spatula.

=Operation.= Under cocaine. The puncture is usually made upwards and outwards unless there be some other special indication for its position, such as a ma.s.s of pus in the lower angle of the anterior chamber. The eye is fixed opposite the spot at which the puncture is to be made, and the bent broad needle is pa.s.sed into the anterior chamber through an incision directly behind the limbus. The needle is then withdrawn and is usually followed by a rush of aqueous. The remainder of the aqueous is then evacuated by pressing the lower margin of the wound with an iris spatula. In some cases where a very tenacious hypopyon is present it may be withdrawn with the iris forceps. The only complication liable to occur is prolapse of the iris into the wound, which should be replaced with the spatula, or failing that, removed.

[Ill.u.s.tration: FIG. 123. HOLLOW NEEDLE USED FOR PARACENTESIS OF THE ANTERIOR CHAMBER. This is used when it is desired to examine the aqueous bacteriologically. Care should be taken to see that the cutting blade is sufficiently wide to take the shaft of the needle.]

OPERATIONS FOR PENETRATING WOUNDS OF THE GLOBE

=Indications.= Of all the conditions which a surgeon is called upon to see, penetrating wounds of the globe may present the most difficult problems as to treatment. The most important factors in their treatment and prognosis are--

1. _The time at which the patient presents himself for treatment_ and the condition of the wound are all-important in the prognosis. Thus in the case of a wound which is obviously septic and going to terminate in panophthalmitis the eye should be eviscerated.

2. _The position and extent of the wound._ Formerly it was taught that if the ciliary body were wounded the eye should be excised. The reason for this was that these injuries were so frequently followed by sympathetic ophthalmia owing to prolapse of the iris and ciliary body.

It is now generally recognized that sympathetic ophthalmia only follows if the wound becomes septic, irido-cyc.l.i.tis with kerat.i.tis punctata being present, and it is only after the latter symptom manifests itself that the eye should be excised, provided that the wound be not so extensive as to preclude all chance of recovery from the outset.

_In wounds of the sclerotic_ all portions of the uveal tract and vitreous which prolapse should be removed, and the wound closed with sutures pa.s.sed through the superficial episcleral tissue. Unless the wound be small the prognosis is not good, as it is liable to be followed by irido-cyc.l.i.tis, or, if this does not occur, detachment of the retina may ensue, following on organization of the exudates in the vitreous.

_Wounds of the cornea_ usually result in prolapse of the iris, which should be removed in the manner described under iridectomy (see p. 208).

3. _If the lens be injured._ Unless the wound amounts to little more than a punctured wound of the globe involving the lens, the prognosis is bad. The wound in the lens capsule and the breaking up of the lens mean the presence of soft matter in the anterior chamber--a condition which favours sepsis and is liable to produce increased tension from blocking the angle of the chamber. In patients under thirty the pupil should be dilated with atropine and the lens allowed to absorb--a.s.sisted at a later date by needling, when the eye has entirely settled down after the original injury. If the patient be over thirty it is often extremely difficult to decide whether extraction of the lens should be undertaken at the time of the injury or at a later date. The results of both procedures are very unsatisfactory, and the surgeon should be guided partly by the position and extent of the wound. Given these in a fairly favourable position, it is probable that immediate extraction will give the best result.

4. _If the eye contain a foreign body._ Usually these are pieces of metal or gla.s.s. The following points should be investigated to determine whether the foreign body be in the eye:--

(i) The history of these accidents is usually the same. The patient is chipping with a hammer and chisel, and a piece flies off and strikes the globe. In the case of gla.s.s it is usually a mineral-water bottle which bursts.

(ii) The position and nature of the wound in the cornea and sclerotic.

(iii) The condition of the anterior chamber--whether evacuated or not.

(iv) The tension of the eye, which may be lowered.

(v) The presence of a hole in the iris.

(vi) The presence of traumatic cataract.

(vii) Whether the foreign body is visible with the ophthalmoscope or by focal illumination.

(viii) The localization of the foreign body by the X-rays. The latter is the most important factor of all, since the foreign body may pa.s.s right through the globe and be embedded in the orbit.

[Ill.u.s.tration: FIG. 124. AUTHOR'S CHAIR FOR THE LOCALIZATION OF FOREIGN BODIES IN THE EYE BY THE X-RAYS. A is a rifle sight for centring the anode, C, on the cross wire, B, behind which the photographic plate is subsequently placed. P is the screw clamping the head-piece on to the patient's head. Q is the screw for regulating the height of the tube and the distance from the patient. R is the screw for regulating the height of the head-piece. The inset shows the arm carrying the tube more highly magnified. E is the sliding arm carrying the tube for lateral displacement marked for stereoscopic photographs. F is the pointer for marking the position of the anode. D is the screw for clamping when in position.]