The current understanding of the pathobiology of endophthalmitis and the treatment strategy allow us to treat endophthalmitis more definitively than ever before. A seminal prospective randomized clinical trial has provided the evidence for treating endophthalmitis after cataract surgery with intravitreal antibiotics with or without vitrectomy.1 A single-port pars plana entry for vitreous biopsy and intravitreal antibiotic injection system (Intrector) is available for quick office-based treatment.2 There are also easy-to-use endophthalmitis treatment kits for emergency care that help reduce intravitreal antibiotic preparation (currently for ceftazidime, vancomycin, and voriconazole) dilution errors.3 New laboratory methods help in definite species identification and antibiotic susceptibility testing so as to institute appropriate antibiotic therapy.4,5 Despite all these measures, there is always limited visual recovery after treatment in the real world.6
Hence, prevention of endophthalmitis is more important. The overall incidence of endophthalmitis after cataract surgery has decreased from over 2% in the 1940s to less than 0.05% today.7 This owes much to our better understanding of the pathology and effective steps in prevention of this condition. The 2 most common intraocular interventions all over the world are cataract surgery and intravitreal injections; Staphylococcus species is the usual offending organism in acute infections after either procedure.8-11 Prophylactic measures can be instituted in the preoperative, intraoperative, and postoperative period.
Speaker et al12 have conclusively shown the importance of the patient's own microbial flora in causation of exogenous endophthalmitis. One of the most important, but often neglected, preventive measures is the careful preoperative clinical evaluation of the patient. Clinicians should look for evidence of staphylococcal or seborrheic blepharitis, rosacea, periocular cutaneous disease, conjunctival hyperemia or discharge of purulent material on pressure over the lacrimal passage, history of prolonged use of corticosteroids, and other regional infection. It is not necessary to do a routine culture of the conjunctival flora. The value of preoperative prophylactic topical antibiotic therapy is uncertain. The prolonged preoperative use of broad-spectrum antibiotics is potentially dangerous because it could alter the normal eyelid and conjunctival flora so that more gram negative and opportunistic pathogens emerge.13 Povidone-iodine antisepsis is the only technique to reach category II evidence in reducing endophthalmitis rates. It is generally used before intraocular surgery and intravitreal injections.14,15
Povidone-iodine is an antiseptic used for skin disinfection of patients and the hands of the healthcare providers. It came into commercial use in 1955 and it is on the World Health Organization list of essential medicines. It has minimal toxicity but produces a powerful antimicrobial effect after 1 minute of skin contact. This effect is attributed to the release of free iodine, and the action persists for at least 1 hour. It is believed that iodine penetrates the cell wall and reacts with amino acids and nucleotides, which, ultimately, disrupt the cell's protein synthesis. Povidone-iodine is recommended for both skin (10% solution) and conjunctival (5% solution) application.16 Ideally, it should dry after skin preparation and the conjunctival cul de sac should not be irrigated before 1 minute of contact time.
The intraoperative measures to prevent endophthalmitis include adding antibiotics to infusion solutions,17 intracameral antibiotics,18 and subconjunctival antibiotic injection.19 In a Cochrane review the certainty of evidence for antibiotics in irrigating solutions was very low, for subconjunctival antibiotic injection was moderate, and for intracameral injection was high.20 The European Society of Cataract and Refractive Surgeons (ESCRS) study documented a nearly 5-fold decrease in endophthalmitis with intracameral cefuroxime, 1.0 mg in 0.1 mL, at the conclusion of cataract surgery.21 There are arguments for22 and against23 this practice. One study in India did not find a statistical benefit of using intracameral cefuroxime in prevention of endophthalmitis.24 Another study from India evaluated intracameral moxifloxacin, 0.1 mL 0.5% w/v, and documented 3.5- to 6-fold reduction in endophthalmitis after cataract surgery.25 At the time of writing, we are aware of 2 prospective studies on intracameral antibiotic prophylaxis in cataract surgery, one using intracameral moxifloxacin and the other comparing intracameral cefuroxime and moxifloxacin. The benefit of prophylactic intravitreal antibiotics (vancomycin and ceftazidime) in preventing endophthalmitis in open globe injuries has been shown in a prospective randomized study.26
Postoperative prophylaxis includes topical antibiotics for a varied period and systemic antibiotic. Both the ESCRS study21 (recommended intracameral cefuroxime) and the Indian study25 (recommended intracameral moxifloxacin) used postoperative topical antibiotic. A survey of over 4000 ophthalmologists in India revealed a preference for using topical antibiotic both before and after cataract surgery (P.K. Maharana, J.K. Chhablani, T. Das, et al; unpublished data; 2017). Similar to not using topical antibiotics after intravitreal injection,27 there are also attempts to not use topical antibiotics after intracameral antibiotic therapy in cataract surgery.28 Systemic antibiotics are not given normally, though in view of the excellent intravitreal penetration of fluoroquinolone (chiefly ciprofloxacin) one might consider it in high-risk patients.29
IMPACT OF EVIDENCE
Two items of evidence seem to have impacted the practice of prophylaxis in endophthalmitis. They are preoperative preparation of the eye and skin around the eye with 5% povidone-iodine and intracameral antibiotic at the conclusion of cataract surgery. Currently, preparation of eyes with povidone-iodine is a standard of care; even frequent conjunctival surface irrigation with 0.25% povidone-iodine is suggested.30 Many are switching to intracameral antibiotic31,32 or willing to change when a commercial preparation is available.33
Research will continue in this area. Equally important is vigilant clinicians with meticulous attention to patient selection, surgical preparation, and training of healthcare personnel. A checklist of all procedures and practices goes a long way in reducing postoperative endophthalmitis.
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3. Das T, Ravilla RD, Ravilla SD, et al. The endophthalmitis kit. Asia Pac J Ophthalmol (Phila).
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6. Das T, Kunimoto DY, Sharma S, et al; Endophthalmitis Research Group. Relationship between clinical presentation and visual outcome in postoperative and posttraumatic endophthalmitis in South Central India. Indian J Ophthalmol.
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28. Zhou AX, Messenger WB, Sargent S, et al. Safety of undiluted intracameral moxifloxacin without postoperative topical antibiotics in cataract surgery. Int Ophthalmol.
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31. Gore DM, Little BC. United Kingdom survey of antibiotic prophylaxis practice after publication of ESCRS endophthalmitis study. J Cataract Refract Surg.
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33. Han DC, Chee SP. Survey of practice preference pattern in antibiotic prophylaxis against endophthalmitis after cataract surgery in Singapore. Int Ophthalmol.