Endophthalmitis After Cataract Surgery: Management by the Retinal Physician

INGRID U. SCOTT, MD, MPH · HARRY W. FLYNN, JR., MD

Retinal physicians are usually involved in the management of endophthalmitis associated with cataract surgery (Figure 1). It has been estimated that the risk of endophthalmitis following cataract surgery is approximately 1 in 1000. Since there are over 2 million cataract operations per year performed in the United States,¹ the magnitude of this problem is significant. Current management of endophthalmitis after cataract surgery is based largely on data provided by the Endophthalmitis Vitrectomy Study (EVS), a multicenter clinical trial sponsored by the National Eye Institute that compared immediate pars plana vitrectomy (PPV) to immediate vitreous tap, and intravenous antibiotics to no intravenous antibiotics, for the treatment of acute-onset (within 6 weeks) endophthalmitis following cataract surgery or secondary intraocular lens (IOL) implantation.^2,3

Figure 1. Acute-onset endophthalmitis following clear corneal cataract surgery.

Theoretical advantages of PPV include debriding intravitreal infection, removing vitreous opacities obstructing vision, collecting intraocular specimens for culture, and allowing better distribution of antibiotics.⁴ Potential disadvantages of PPV, compared to vitreous tap and injection of intravitreal antibiotics in the office, include treatment delay and higher expense. Before the EVS, widely divergent opinions existed regarding the role of vitrectomy in endophthalmitis management, ranging from vitrectomy for all cases vs use of vitrectomy only for the most severe cases.

THE IMPACT OF THE ENDOPHTHALMITIS VITRECTOMY STUDY

Even with EVS data, the role of systemic antibiotics has been controversial.⁵ In the early 1970s, endophthalmitis was generally managed with systemic antibiotics, which usually meant hospitalization for 5 or more days of intravenous administration. In 1974, experimental and clinical studies were published regarding the use of intravitreal antibiotics to augment the effectiveness of systemic, topical, and periocular antibiotics.^6-8 During the late 1970s, intravitreal antibiotics (in addition to systemic antibiotics) became standard treatment for clinically suspected endophthalmitis. There was at least 1 report of favorable outcomes with endophthalmitis treated with without systemic antibiotics.⁵ In spite of improved outcomes with intravitreal antibiotics, most clinical series prior to the EVS included treatment outcomes of patients with complex pathology, making it difficult to interpret the impact of systemic antibiotics and vitrectomy on visual results.

The EVS² demonstrated that, in subjects whose visual acuity (VA) on presentation was hand motions or better, no difference existed in visual outcome regardless of whether immediate PPV was performed; but in the subgroup of patients with presenting vision of light perception only, immediate PPV was associated with a 3-fold increase in the frequency of achieving 20/40 or better VA, approximately a 2-fold chance of achieving 20/100 or better, and a 50% decrease in the frequency of severe visual loss to <5/200 VA. The EVS showed no difference in final VA or media clarity regardless of use of systemic antibiotics. The single most important predictor of visual outcome was presenting VA.

THE EVOLUTION OF CATARACT SURGERY

Cataract surgery has evolved from mostly extracapsular cataract extraction and scleral tunnel phacoemulsification at the time of the EVS to mostly clear corneal incision phacoemulsification today. In fact, according to a survey of the membership of the American Society of Cataract and Refractive Surgery, the use of clear corneal incisions during cataract surgery increased from approximately 5% in 1993 to 72% in 2003.⁹ A recent report of acute-onset endophthalmitis following clear corneal cataract surgery demonstrates similar presenting clinical features, microbial spectrum, and visual outcomes to the EVS.¹⁰ Differences identified were the time to endophthalmitis presentation after cataract surgery (6 days in the EVS vs 13 days in the clear corneal series) and the absence of systemic antibiotic utilization in the clear corneal series. This recent report validates the findings and the importance of the EVS.

Currently, most cases of acute-onset endophthalmitis following cataract surgery are managed without the expense and patient burden associated with intravenous antibiotics (and associated inpatient hospital stays) and without the expense associated with vitrectomy. Rather, most patients with endophthalmitis are now treated as outpatients in an office or ambulatory surgery center with vitreous tap and intravitreal antibiotic injection. Oral fluoroquinolones have been advocated because of their favorable intravitreal penetration, but the positive impact of this treatment has not yet been demonstrated.

TREATMENT STRATEGIES

Optimal strategies for the successful treatment of endophthalmitis depend on knowledge of the most common microbial isolates. In the EVS, gram-positive micrococci (coagulase-negative staphylococcus) were the most common organisms, occurring in approximately 70% of culture-positive cases, and 94% of isolates were gram-positive organisms. Staphylococcus epidermidis and Staphylococcus aureus were the most common isolates. All EVS gram-positive isolates were sensitive to vancomycin. While cephalosporins may provide satisfactory coverage for some staphylococcal infections, a large percentage of staphylococcal isolates will be resistant to this antibiotic class. However, ceftazidime is effective for most gram-negative organisms. Many retinal physicians prefer to use ceftazidime rather than amikacin for coverage of gram-negative organisms because of the concern for macular infarction with aminoglycosides (Figure 2).

Figure 2. (A) Macular infarction after use of amikacin; (B) Capillary nonperfusion in the macula typical of macular infarction.

Delayed-onset endophthalmitis is defined as endophthalmitis occurring more than 6 weeks after cataract surgery. Compared to acute postoperative endophthalmitis, chronic cases are typically marked by relatively mild inflammation and an indolent course. Propionibacterium acnes, a gram-positive, anaerobic pleomorphic rod, is a common causative organism. Other causative bacterial organisms may include S. epidermidis, Corynebacterium species, Xanthomonas maltophilia, and Alcaligenes xylosoxidans. Causative fungal organisms may include Candida parapsilosis, other Candida species, Paecilomyces species, Aspergillus species, and Acremonium species.

When a less virulent organism is suspected, such as P. acnes, Xanthomonas maltophilia, or various gram-negatives, anaerobic cultures of both the aqueous and vitreous should be obtained and held at least 2 weeks for culture. In the initial management of P. acnes endophthalmitis with a white intracapsular plaque, PPV with central capsulectomy and standard intravitreal antibiotics are generally recommended (Figure 3). Alternatively, many surgeons treat P. acnes endophthalmitis with a trial of intravitreal antibiotics and close observation. If the initial treatment approach does not eliminate the infection, PPV with total capsulectomy and IOL removal or exchange can be considered.

Figure 3. (A, left photo) Progressive white plaque within the capsular bag typical of P. acnes endophthalmitis; (B, right photo) Following vitrectomy, removal of the central capsule and plaque and injection of intravitreal antibiotics, the patient has had no recurrence during a 3-year follow-up.

In cases of suspected fungal endophthalmitis, intravitreal amphotericin B (0.005 mg/0.1 mL) is generally the first-line treatment selected. However, voriconazole (0.050 mg/0.1 mL), miconazole (0.025 mg/0.1 mL), or fluconazole (0.010 mg/0.1 mL) may be used in amphotericin-resistant cases. Aspergillus endophthalmitis carries a relatively worse prognosis than Candida endophthalmitis, and treatment with PPV and intravitreal amphotericin B is usually considered.

The use of prophylactic topical antibiotics to prevent endophthalmitis after cataract surgery is a common practice. In a recent study of 42 patients with acute-onset endophthalmitis occurring within 6 weeks of cataract surgery, 31 (74%) were treated with perioperative topical gatifloxacin or moxifloxacin and 24 (57%) had been taking 1 of these antibiotics continuously since the time of cataract surgery.¹¹ Sensitivities were performed on 14 gram-positive isolates and the fluoroquinolones were effective in 50% or less of gram-positive isolates. Fortunately, all gram-positive organisms were sensitive to vancomycin. In another report, 4 patients treated with fourth-generation fluoroquinolones at the time of and after cataract surgery developed postoperative endophthalmitis during follow-up.¹² Each patient received a 5% povidone-iodine prep, sterile drape wrapped around the lids and lashes, and a sterile eyelid speculum.

In a study of 111 coagulase-negative Staphylococcus isolates recovered during a 15-year period from endophthalmitis patients,¹³ the fourth-generation fluoroquinolones demonstrated in vitro efficacy of <80%. Resistance increased significantly during the last 5 years of the study compared to the 2 preceding 5-year periods. Fluoroquinolones may reduce colony counts of certain bacteria, but these antibiotics do not prevent endophthalmitis.

CONCLUSION

In summary, the Endophthalmitis Vitrectomy Study has had a significant effect on the management of patients with acute-onset endophthalmitis after cataract surgery. Treatment of such patients generally follows EVS guidelines and most are now treated in the office with vitreous tap and intravitreal antibiotics rather than in the operating room with PPV, and most are managed as outpatients without the need for hospitalization and without intravenous administration of antibiotics. RP

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