Background
Postoperative endophthalmitis is defined as severe inflammation involving both the anterior and posterior segments of the eye after intraocular surgery. [1] Typically, postoperative endophthalmitis is caused by the perioperative introduction of microbial organisms into the eye either from the patient's normal conjunctival and skin flora or from contaminated instruments. Once organisms gain access to the vitreous cavity, overwhelming inflammation is likely to occur, making rapid recognition, diagnosis, and treatment critical in optimizing final outcomes. Although most cases of postoperative endophthalmitis occur within 6 weeks of surgery, infections seen in high-risk patients or infections caused by slow-growing organisms may occur months or years after the procedure. [2]
Pathophysiology
The Endophthalmitis Vitrectomy Study (EVS) demonstrated that most isolates causing clinical endophthalmitis are introduced into the eye from the patient's conjunctival flora. [3] However, contamination of sterilized instruments, disposable supplies, prepared solutions, surgical field, or the intraocular lens all have been reported. Epidemic clusters of endophthalmitis have resulted from these types of external contaminations. [4, 5]
Once bacteria are introduced into the eye, risk factors that may increase the risk of endophthalmitis include rupture of the posterior capsule, retained lens material, and surgical procedure. Published studies have demonstrated an increased risk of endophthalmitis after placement of a secondary intraocular lens, possibly due to increased surgical time or ocular manipulation. [6] Prolene haptic sutures also have been implicated as a possible risk factor for the development of endophthalmitis due to the surface properties of the material.
Once clinical infection occurs, damage to ocular tissues is believed to occur due to direct effects of bacterial replication as well as initiation of a fulminant cascade of inflammatory mediators. Endotoxins and other bacterial products appear to cause direct cellular injury while eliciting cytokines that attract neutrophils, which enhance the inflammatory effect. Thus, recent efforts in controlling the damaging effects of endophthalmitis in experimental models have focused on identifying not only appropriate antibiotics for control of the infectious agent but also on anti-inflammatory agents that might disrupt the immunologic events that occur after infection.
Epidemiology
Frequency
United States
Postoperative endophthalmitis remains a rare complication of intraocular surgery. Of the 21,972 patients undergoing cataract extraction at the Bascom Palmer Eye Institute (BPEI) from 1995-2001, 8 (0.04%) developed endophthalmitis. During the same period at BPEI, the incidence of endophthalmitis was 0.2% after secondary intraocular lens (IOL) implantation, 0.03% after pars plana vitrectomy, 0.08% after penetrating keratoplasty, and 0.2% after glaucoma filtering surgery. [6] However, some studies have reported a potentially higher rate of acute endophthalmitis following cataract surgery in recent years, presumably secondary to the adoption of sutureless wounds. [7, 8, 9, 10]
Attention to prophylaxis appears to be the key in reducing the incidence of acute postoperative bacterial endophthalmitis. The requirement by the Bascom Palmer Eye Institute for the use of povidone-iodine prior to surgery played a major role. [11]
International
The rate of postoperative acute endophthalmitis among developed nations is similar to that of the United States. [12, 13]
Mortality/Morbidity
Fortunately, postsurgical endophthalmitis, unlike endogenous endophthalmitis, rarely causes any extraocular complications. Rarely, untreated cases can lead to late panophthalmitis and orbital cellulitis, prompting need for enucleation.
Morbidity associated with postoperative endophthalmitis can be substantial and is related not only to the acute process but also to late sequelae. In general, the risk forf severe visual loss in patients with acute endophthalmitis is higher in patients who develop infections from more virulent organisms and do not seek treatment promptly. [3, 14, 15] Fortunately, 70-80% of patients with postoperative endophthalmitis have infections caused by coagulase-negative staphylococci, and the visual prognosis in these cases is usually good with rapid treatment.
Race
No racial predilection exists.
Sex
No sexual predilection exists.
Age
No age predilection exists.
Patient Education
One of the most important factors related to good visual outcomes after postoperative endophthalmitis is prompt recognition and diagnosis. It is critically important to counsel patients to look for the early signs and symptoms of endophthalmitis (eg, pain, redness, decreased vision) and to contact the operating physician immediately if present. If diagnosed and treated promptly, most cases may result in acceptable visual outcomes.
