There are a variety of procedures that can be done safely and inexpensively at the slit lamp. This presentation will detail several of them.There are many clinical situations in which it is useful to perform a paracentesis with a half-inch 30 g needle held by the hub to lower the intraocular pressure in a very controlled fashion. I first apply apraclonidine 0.5% for vasoconstriction and proparacaine for anesthesia, and then prep the conjunctival sac and lashes with povidone iodide solution (Betadine). After rinsing out the povidone, the patient is positioned at the slit lamp and the lids are held open manually or with a speculum. The needle hub is grasped between the thumb and forefinger and the back of the hand rested on the patient's cheek for stabilization. Note that the needle is used without a syringe. The tip of the needle then enters the cornea inferotemporally (Fig. 1a) in a path longer than iris parallel (Fig. 1b), so that the track will be self-sealing, enters the anterior chamber, and after ten seconds is withdrawn. Quite conveniently, the pressure necessary to force fluid through a half-inch 30 g needle is about 12 mmHg, so that the decompression stops automatically at that pressure and the anterior chamber does not flatten.
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