Endophthalmitis

Abstract

Tube shunts have become an important part of the surgical armamentarium for controlling intraocular pressure (IOP). Once reserved for use only in refractory cases, they are rapidly gaining popularity as an effective alternative to trabeculectomy and cyclodestruction for lowering IOP in patients who are not satisfactorily controlled on medications. Although trabeculectomy remains the most commonly performed glaucoma surgery, tube shunts offer some significant advantages. One of these advantages is a theoretically reduced risk of one of the most feared complications of any penetrating ocular surgery— endophthalmitis. The incidence of late-onset infections such as blebitis and endophthalmitis after trabeculectomy with antifibrotic agents is alarmingly high compared to other penetrating intraocular surgeries, perhaps as high as 5% over 3–5 years. Trabeculectomies produce a perilimbal bleb that may be made thinner and more ischemic by the concomitant use of antifibrotics such as 5-fluorouracil and mitomycin-C (MMC). These anteriorly placed blebs are more exposed, more fragile, and more prone to become infected than the robust, thicker, and more posteriorly located blebs overlying a tube shunt plate. Gedde and associates reported a 1% (1 of 107 eyes) incidence of endophthalmitis after Baerveldt® Glaucoma Implant (BGI) placement compared to a 5% (5 out of 105 eyes) incidence after trabeculectomy with MMC after 5 years of follow-up. However, despite this potential advantage, endophthalmitis still does occur in association with shunts, and it is essential to understand the risk factors for its occurrence and the proper steps to take to prevent, recognize, and treat this potentially devastating complication. Distinguishing sterile from infectious endophthalmitis can be difficult. Signs suggestive of an infectious endophthalmitis include marked inflammation, hypopyon, fibrinoid anterior chamber reaction, corneal edema, marked conjunctival congestion, eyelid edema, vitritis, and retinal periphlebitis. Signs suggestive of a noninfectious etiology are a gradual onset of symptoms, such as pain, redness, and inflammation, in the absence of tube or plate erosion. Sterile endophthalmitis one month after discontinuation of corticosteroid therapy postoperatively has been reported. Possible causes for noninfectious (sterile) endophthalmitis include exacerbated preexisting uveitis, iris trauma, and toxicity from foreign substances introduced during surgery.