Infectious endophthalmitis is a devastating vision-threatening condition involving inflammation of the entire globe and its intraocular contents (Figure 1). The most common form of infectious endophthalmitis tends to result from direct inoculation of an organism from outside the body (ie, exogenous as opposed to endogenous), most commonly after cataract surgery or intravitreal injection. It tends to present acutely within 3 to 21 days after the procedure.
AT A GLANCE
• Infectious endophthalmitis is a vision-threatening condition that involves inflammation of the entire globe and its intraocular contents.
• In the era of MIVS, early vitrectomy for endophthalmitis may be of significant benefit in removing infectious material and vitreous debris.
• Active communication with patients and close follow-up of evolving clinical response are paramount in order to achieve the best outcomes.
Acute-onset endophthalmitis (within 6 weeks of an intraocular procedure) is typically caused by coagulase-negative Staphylococcus and Streptococcus species, and less commonly by gram-negative organisms.1 Chronic or delayed-onset endophthalmitis (beyond 6 weeks after intraocular surgery) is typically due to Propionibacterium acnes, but may also involve coagulase-negative Staphylococcus or fungi.2 Bleb-associated endophthalmitis can occur months to years after filtering surgery and is most commonly caused by Streptococcus, Haemophilus, or gram-positive organisms. We previously reviewed 10 years of endophthalmitis cases (n = 758) and found gram-positive organisms to be the causative pathogen in 80% of cases, followed by gram-negative (11%) and fungi (9%).1
It is inherently difficult to acquire top-tier evidence for endophthalmitis incidence rates because studies are usually of low power, owing to the rare incidence rate (ie, one per several thousand) of endophthalmitis in the setting of cataract surgery or intravitreal injection. Additionally, nonhomogeneous study populations, differing surgical techniques (eg, clear corneal vs. scleral incision; use of a speculum, oral or facial mask, and/or sterile gloves), and differing methods of reporting make extrapolation difficult. Nonetheless, Figure 2 shows a summary of evolving endophthalmitis incidence rates.3-11
With regard to prophylaxis during intravitreal injection, the best evidence currently is for preoperative povidone-iodine antisepsis, with a grade B recommendation, indicating that this practice is moderately important to clinical outcome.12 With regard to post–cataract surgery endophthalmitis, the value of intraoperative intracameral antibiotics is the subject of significant debate, and recent evidence suggests that adoption of this practice may reduce the incidence of this devastating complication.13,14
VALUE OF VITRECTOMY
The Endophthalmitis Vitrectomy Study (EVS) taught us that immediate vitrectomy did not produce significantly different visual outcomes in patients with better than light perception vision at presentation.3 Interesting findings of the EVS included that more than one fourth (26%) of patients had no pain on presentation and 14% did not have a hypopyon.3 Additionally, 94.2% of culture-confirmed cases involved gram-positive bacteria, of which 70% were coagulase-negative Staphylococcus epidermidis.3
The EVS represented large-gauge vitrectomy, and its results may not be applicable to the smaller-gauge microincisional vitrectomy surgery (MIVS) techniques widely performed today. We believe that, in the era of MIVS, early vitrectomy for endophthalmitis may be of significant benefit in removing infectious material and vitreous debris, which are paramount, respectively, for accelerating infection clearance and optimizing visual outcomes.
The EVS relied on older vitrectomy techniques with known increased rates and severity of complications, such as retinal detachment and vitreous hemorrhage. By contrast, MIVS techniques provide faster and safer surgical options for eyes with severe inflammation. We recently reported 10-year data showing that small-gauge vitrectomy for endophthalmitis yields final visual outcomes comparable to those of vitrectomy using 20-gauge instrumentation.15 In vitro laboratory testing revealed no significant difference in rates of culture growth with different vitrectomy gauge sizes or vitreous cutting speeds.15
Our preferred technique for infectious endogenous endophthalmitis is vitreous biopsy, or tap, via a short 25-gauge needle on a 3- or 5-mL syringe. This is followed by injection with intravitreal antibiotics at the pars plana in the clinic setting. The antibiotics we use most commonly are intravitreal ceftazidime 2.25 mg/0.1 mL and vancomycin 1 mg/0.1 mL. In patients with known serious penicillin allergy, intravitreal amikacin 400 µg/0.1 mL can be considered. Additionally, intravitreal dexamethasone 400 µg/0.1 mL is often used as an adjunct to address the severe secondary inflammatory state when the suspicion for fungal etiologies is low.
If a vitreous sample cannot be obtained due to the viscosity of the vitreous fluid, an anterior chamber aqueous sample is obtained for cultures via a short 30-gauge needle on a 1-mL syringe at the limbus. Note that, in the EVS, aqueous samples were positive in only 42% of eyes.3
We expect the clinical presentation to sometimes worsen within 24 hours of the injection of antibiotics. If no clinical improvement is seen, we typically perform pars plana vitrectomy within 48 to 72 hours of initial presentation with the idea that the vitreous acts as a culture medium for microorganisms. This is most likely the reason for the low incidence of endophthalmitis following routine pars plana vitrectomy surgery.
Our surgical technique for endophthalmitis recalcitrant to the clinical treatment described above includes a five-trocar setup using three standard pars plana trocar-cannulas and two limbal anterior trocar-cannulas (Figure 3).
The two limbal ports are typically necessary in cases of endophthalmitis that are complicated by significant anterior segment inflammatory reaction and/or media opacity. Anterior infusion is established and verified at the corneal limbus while the second anterior cannula is used for anterior chamber washout and membranectomy of fibrin and inflammatory membranes with the vitreous cutter and/or retinal forceps.
When media clarity is improved and the posterior segment can be better visualized, the infusion line of balanced saline solution can be moved to the pars plana, and a complete posterior vitrectomy can then be performed. In eyes in which pars plana infusion still cannot be visualized, posterior vitrectomy can be performed with the anterior infusion cannula. To see this technique in its entirety, please see the Video.
ROLE OF SYSTEMIC ANTIBIOTICS
Watch it Now
Vitrectomy for endophthalmitis performed with anterior cannulas for infusion, anterior chamber washout, and membranectomy.
Another point of contrast between contemporary practice and the techniques used in the EVS concerns the use of systemic antibiotics. Although systemic antibiotic treatment was found not to provide additional treatment benefit in the EVS, the study took place before the availability of oral fourth-generation fluoroquinolones (eg, moxifloxacin), which have excellent ocular and vitreous penetration.16-18 In the event of endophthalmitis, a 10- or 14-day course of oral moxifloxacin 400 mg daily provides additional broad-spectrum coverage with good vitreous penetration. We tend to supplement this in a similar manner with topical fluoroquinolones, steroids, and cycloplegic agents for added antimicrobial, antiinflammatory, and analgesic effects, respectively.
Although bacteria comprise the majority of causative pathogens in postoperative exogenous endophthalmitis, other organisms such as fungi must be considered.2 Additionally, we recently showed that Acanthamoeba caused an atypical postoperative panuveitis in a patient who underwent multiple penetrating keratoplasty surgeries (Figure 4). For the first time, we histologically documented Acanthamoeba involvement in all ocular layers, including the choroid.19 This case example serves as a reminder to keep one’s mind open when suspected cases of infectious endophthalmitis are encountered. Active communication with patients and close follow-up of evolving clinical response are paramount in order to achieve the best outcomes. n
1. Almeida DR, Miller D, Alfonso EC. Anterior chamber and vitreous concordance in endophthalmitis: implications for prophylaxis. Arch Ophthalmol. 2010;128(9):1136-1139.
2. Xu K, Almeida DRP, Chin EK, Mahajan VM. Delayed fungal endophthalmitis secondary to Curvularia. Am J Ophthalmol Case Rep. 2016 [in press].
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7. Moshirfar M, Feiz V, Vitale AT, et al. Endophthalmitis after uncomplicated cataract surgery with the use of fourth-generation fluoroquinolones: a retrospective observational case series. Ophthalmology. 2007;114(4):686-691.
8. Miller JJ, Scott IU, Flynn HW Jr, et al. Acute-onset endophthalmitis after cataract surgery (2000-2004): incidence, clinical setting, and visual acuity outcomes after treatment. Am J Ophthalmol. 2005;139(6):983-987.
9. Taban M, Behrens A, Newcomb RL, et al. Acute endophthalmitis following cataract surgery: a systematic review of the literature. Arch Ophthalmol. 2005;123(5):613-620.
10. West ES, Behrens A, McDonnell PJ, Tielsch JM, Schein OD. The incidence of endophthalmitis after cataract surgery among the US Medicare population increased between 1994 and 2001. Ophthalmology. 2005;112(8):1388-1394.
11. Hatch WV, Cernat G, Wong D, Devenyi R, Bell CM. Risk factors for acute endophthalmitis after cataract surgery: a population-based study. Ophthalmology. 2009;116(3):425-430.
12. Ciulla TA, Starr MB, Masket S. Bacterial endophthalmitis prophylaxis for cataract surgery: an evidence-based update. Ophthalmology. 2002;109(1):13-24.
13. Creuzot-Garcher C, Benzenine E, Mariet AS, et al. Incidence of acute postoperative endophthalmitis after cataract surgery: a nationwide study in France from 2005 to 2014. Ophthalmology. 2016;123(7):1414-1420.
14. Schwartz SG, Grzbowski A, Flynn HW Jr. Antiobiotic prophylaxis: different practice patterns within and outside the United States. Clin Ophthalmol. 2016;10:251-256.
15. Almeida DR, Chin EK, Shah SS, et al. Comparison of microbiology and visual outcomes of patients undergoing small-gauge and 20-gauge vitrectomy for endophthalmitis. Clin Ophthalmol. 2016;10:167-172.
16. Hariprasad SM, Shah GK, Mieler WF, et al. Vitreous and aqueous penetration of orally administered moxifloxacin in humans. Arch Ophthalmol. 2006;124(2):178-182.
17. Fuller JJ, Lott MN, Henson NM, et al. Vitreal penetration of oral and topical moxifloxacin in humans. Am J Ophthalmol. 2007;143(2):338-340.
18. Lott MN, Fuller JJ, Hancock HA, et al. Vitreal penetration of oral moxifloxacin in humans. Retina. 2008;28(3):473-476.
19. Mammo Z, Almeida DR, Cunningham MA, Chin EK, Mahajan VB. Acanthamoeba endophthalmitis after recurrent keratitis and nodular scleritis [published online ahead of print May 5, 2016]. Retin Cases Brief Rep.
David R.P. Almeida, MD, MBA, PhD
• private practice, VitreoRetinal Surgery, PA, in Minneapolis, Minn.
• financial disclosure: Allergan, Citrus Therapeutics, Genentech
Eric K. Chin, MD
• private practice, Retina Consultants of Southern California, Redlands, Calif.
• financial disclosure: Citrus Therapeutics