Indications. Evacuation of the contents of the anterior chamber is performed for several conditions:—
(i) To reduce the tension of the eye when due to an altered consistency of the aqueous, as for instance in cyclitis.
(ii) To evacuate pus from the anterior chamber following metastatic infection.
(iii) To evacuate the anterior chamber in bad corneal ulceration, especially when associated with hypopyon and tension.
(iv) To examine the aqueous for organisms in cases of cyclitis following operation or of metastatic origin.
(v) To evacuate soft lens matter (see [p. 194]).
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.
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 (Sämisch’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needle, attached to a hypodermic syringe, should be passed into the anterior chamber at the limbus and the fluid withdrawn into the syringe by an assistant (Fig. 123). The spot through which the needle is passed is first touched with the electro-cautery to ensure asepsis.