Aqueocentesis is the aspiration (removal by sucking action) of aqueous humor from the anterior (frontal portion) chamber of the eye. It may also involve aspiration of cells from masses in the anterior segment or from the surface of the iris.

What Does Aqueocentesis Reveal?

Aqueocentesis can be performed as both a diagnostic tool and a therapeutic measure. In cats the procedure is most commonly used as a diagnostic tool. Examination of aqueous may help identify the cause of anterior uveitis (inflammation of the front portion of the eye) or endophthalmitis, particularly if systemic laboratory tests fail to yield a definitive diagnosis. Aqueous humor may also be examined when iris masses or tumors are suspected.

In dogs, it is less common to perform aqueocentesis for diagnostic purposes, but the indications are similar to that for cats. The procedure is sometimes performed to treat cases of acute glaucoma in dogs. Removal of aqueous humor is usually considered as a last resort in those cases with acute, severe elevations of intraocular pressure that are unresponsive to medical therapy. The technique is most often used to control severe alterations in intraocular pressure just prior to surgery, or in the immediate post-operative period following laser therapy.

How is Aqueocentesis Performed?

With the eye gently immobilized by specialized forceps, a syringe attached to a needle is carefully inserted into the front portion of the eye (into the anterior chamber). For diagnostic purposes, a small amount of fluid (about 0.1 ml) is sucked into the syringe and then analyzed under a microscope. If the purpose of the aqueocentesis is therapeutic, a smaller needle without a syringe may be used. The needle is inserted into the eye and the fluid is allowed to drip out. This fluid is blotted with a sponge as it drains until the intraocular pressure decreases.

The procedure typically lasts only a few minutes.

Is Aqueocentesis Painful?

Because the procedure is performed under sedation and/or local anesthesia, no pain is involved. There may be some pain and discomfort following the procedure. As with people, the pain experienced will vary among individual animals.

Is Sedation or Anesthesia Required for Aqueocentesis?

Most animals must be sedated for the procedure. Short-acting sedatives/anesthetics are usually sufficient as the procedure takes only a few minutes.