Postoperative endophthalmitis is defined as severe inflammation involving both the anterior and posterior segments of the eye after intraocular surgery. 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.
The Endophthalmitis Vitrectomy Study (EVS) demonstrated that most isolates causing clinical endophthalmitis are introduced into the eye from the patient's conjunctival flora.[1] 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.[2, 3]
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.[4] 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.
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.[4] 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.[5, 6, 7, 8]
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.[9]
International
The rate of postoperative acute endophthalmitis among developed nations is similar to that of the United States.[10, 11]
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 of 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.[1, 12, 13] 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.
No racial predilection exists.
No sexual predilection exists.
No age predilection exists.
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.
Patients with acute postoperative endophthalmitis typically present within 6 weeks of intraocular surgery with moderate to severe eye pain and decreased vision.
The hallmark findings on ophthalmic examination are posterior and anterior chamber inflammation.[12, 13, 14]
Hypopyon is present in most cases.[12, 13, 14]
Other important findings include conjunctival hyperemia and chemosis, corneal edema, wound abnormalities, and associated eyelid or orbital inflammation.
In rare circumstances, patients may develop chronic, infectious endophthalmitis months to years after intraocular surgery. These patients exhibit indolent inflammation, which is initially responsive to corticosteroids, but over time, become refractory to therapy. Although conjunctival hyperemia, corneal edema, and anterior and posterior chamber inflammation are often present, rapid deterioration of vision and hypopyon are not seen frequently.[15, 16]
Risk factors for development of postoperative endophthalmitis may include the following:
In the EVS, a prospective randomized clinical trial that evaluated the management of acute postoperative (cataract extraction or secondary IOL implantation) endophthalmitis, the most common organisms isolated were coagulase-negative staphylococci (70%), Staphylococcus aureus (9.9%), and streptococci species (9.0%). Infections caused by gram-negative organisms were seen in 6% of cases.[1, 20]
Endophthalmitis following other types of intraocular surgery has a similar microbiological profile with the following exceptions:
The main complication associated with postoperative endophthalmitis is severe visual loss. This occurs most commonly in patients who develop infections from virulent organisms (non–coagulase-negative staphylococci, streptococci, and gram-negative organisms), receive delayed treatment, or have vision worse than hand motion at presentation.[1, 13, 20]
An important late complication of treatment of postoperative endophthalmitis remains retinal detachment.[27] In a report from the EVS, retinal detachment can occur in 10% of patients after treatment. Possible factors involved include iatrogenic retinal tears at the time of vitreous tap, injection of antibiotics, vitrectomy, late tears associated with subtotal posterior vitrectomy, or just a consequence of the infection/inflammation and the secondary retinal necrosis. Prompt treatment of retinal detachment may result in good visual outcomes in select cases.[13]
Most clinicians obtain vitreous and aqueous samples for microbiologic identification of the offending organism.[13]
B-scan (ultrasound): Determine whether there is vitreous involvement of the inflammation. It is also important to note the presence of retinal and choroidal detachment, which is important in the management and prognosis.[12, 13, 23]
The EVS evaluated the role of immediate pars plana vitrectomy (VIT) versus intraocular antibiotic injection (TAP) and systemic antibiotics in the treatment of acute postoperative endophthalmitis. Patients were included in the study if they presented within 6 weeks of cataract extraction or secondary IOL implantation, had an initial visual acuity between 20/50 and light perception, and had a view sufficient to perform a VIT. Exclusion criteria included prior treatment of endophthalmitis, previous intraocular surgery, or preexisting eye disease limiting visual acuity to 20/100 or worse. Once enrolled, the 420 patients were assigned to immediate initial TAP or VIT, and then subsequently assigned to receive intravenous antibiotics. The main treatment outcomes evaluated included final visual acuity and media clarity.[12]
The results demonstrated no difference in final visual outcomes in patients who underwent initial TAP or VIT if presenting visual acuity was better than light perception. However, in patients presenting with light perception vision, those who underwent initial VIT were 3 times more likely to achieve 20/40 vision or better, twice as likely to maintain 20/100 vision or better, and had a nearly 50% reduction in the risk of severe visual loss (< 5/200), compared to patients who underwent TAP. No long-term difference occurred in media clarity between the treatment groups. Intravenous antibiotics had no effect on either treatment outcome.[12, 24]
Subsequent reports by the EVS demonstrated that visual outcome in the trial was based largely on the presenting signs and offending organisms.[1, 20, 23] Cases due to coagulase-negative staphylococci or if no organism was isolated demonstrated the best final visual outcome. Endophthalmitis caused by other gram-positive or gram-negative infections had significantly worse final visual acuity. The most common cause for moderate and severe visual loss was macular abnormalities (eg, epiretinal membrane, macular edema, pigmentary degeneration, macular ischemia) and media opacities.
The EVS demonstrated that in many cases of acute postoperative endophthalmitis, patients can be treated with initial TAP without intravenous antibiotic and have a favorable outcome. However, in patients who present early after surgery with overwhelming inflammation and rapidly declining vision, early vitrectomy may be warranted since patients in the EVS who were infected with virulent organisms appeared to have a better visual outcome with vitrectomy than tap and inject. In addition, although no benefit was demonstrated with the use of intravenous antibiotics, the choice of amikacin for gram-positive coverage in the EVS has been questioned because of its poor penetration into the vitreous cavity in animal models. Therefore, in cases of rapid deterioration of vision, the use of appropriate systemic antibiotics can be considered.
Since the EVS specifically excluded patients with postoperative endophthalmitis who underwent any procedure other than cataract surgery, therapy for these cases must be individualized. In patients with conjunctival filtering bleb-associated endophthalmitis, earlier vitrectomy may be preferred in selected cases because of more profound inflammation and the increased probability of more virulent organisms.[13, 21] In chronic postoperative endophthalmitis, initial surgical treatment also may offer advantages over intraocular antibiotics alone.[15, 16]
Vitreous cultures typically grow more often from undiluted samples. Therefore, samples should be obtained by an automated vitrectomy instrument before instillation of balanced salt solution through the posterior infusion cannula.
In chronic postoperative endophthalmitis due to P acnes, intraocular vancomycin alone has been associated with high rates of persistent inflammation. In contrast, vitrectomy with special attention to either partial or total capsular bag excision without IOL removal has been reported effective in eradicating inflammation without removal of the IOL.[15, 16] Some advocate a stepwise approach with vitrectomy, partial or total capsulectomy, and intravitreal vancomycin, and, if inflammation/infection persists, to proceed with vitrectomy, total capsulectomy, and IOL removal.
The drugs recommended for use in acute postoperative endophthalmitis are discussed in Medication.
Vancomycin has been shown effective against greater than 99% of gram-positive endophthalmitis isolates.
The aminoglycoside amikacin (0.4 mg in 0.1 mL) is useful for gram-negative coverage. Approximately 90% of gram-negative isolates are susceptible to this agent.
Ceftazidime demonstrates similar gram-negative sensitivity profiles as the aminoglycosides and is not associated with retinal toxicity. Therefore, ceftazidime is a reasonable alternative for gram-negative coverage.[13]
The use of intravitreal dexamethasone in the treatment of acute postoperative endophthalmitis remains controversial.[13, 25] Clinicians have used this short-acting corticosteroid to inhibit the inflammatory effects of bacterial endotoxins, host factors, and antibiotics. In a rabbit model of virulent infectious endophthalmitis, dexamethasone was shown to decrease elimination of intraocular vancomycin through the trabecular meshwork, suggesting a new potential benefit to steroid administration.[25]
The EVS recommended rapid intervention with vitrectomy for patients with severe vision loss (light perception) on presentation. It is important to note again that the EVS only evaluated acute endophthalmitis following cataract extraction or secondary IOL implantation. As noted above, cases following other surgical procedures, such as glaucoma filtering procedure and penetrating keratoplasty, should be individually managed because of the lack of prospective randomized studies, with some advocating vitrectomy at the onset.[13, 21, 26]
Initially, administer topical therapy hourly and taper only after clinical improvement is seen.
Examine patients on a daily basis during the initial treatment period to ensure adequate sterilization of the vitreous cavity, to control intraocular inflammation, and to identify the need for additional intervention.
In the EVS, a total of 44 patients (10.5%) underwent an additional procedure during the first week after initial treatment, with 6 undergoing a procedure due to a complication of the disease or treatment and 38 due to worsening inflammation.[23] Of the patients in the TAP group that underwent repeat intraocular cultures, 71% had persistent positive cultures, compared to 13% in the VIT group, suggesting that vitrectomy may be more effective in sterilization of the ocular contents.
The EVS also evaluated the need for additional procedures between 1 week and 1 year, the endpoint for follow-up care. A total of 26.9% of patients underwent a late additional procedure. The most common reasons for intervention included opacified posterior capsule (9.0%), retinal detachment (4.3%), recurrent endophthalmitis (3.3%), and glaucoma (2.6%).
These drugs are recommended for the treatment of acute postoperative endophthalmitis after cataract extraction.
Clinical Context: Indicated for treatment of serious or severe infections caused by gram-positive organisms.
Clinical Context: Third-generation cephalosporin with broad-spectrum, gram-negative activity; lower efficacy against gram-positive organisms; higher efficacy against resistant organisms. Arrests bacterial growth by binding to one or more penicillin-binding proteins.
Therapy must be comprehensive and cover all likely pathogens in the context of this clinical setting.
Clinical Context: Decreases inflammation by suppressing migration of polymorphonuclear leukocytes and reducing capillary permeability.
Clinical Context: Synthetic analog of naturally occurring glucocorticoid used to suppress the inflammatory response.
Have anti-inflammatory properties and cause profound and varied metabolic effects. Corticosteroids modify the body's immune response to diverse stimuli.