Author
Year
Country
Incidence (%)
Jabbarvand et al. [13]
2016
Iran
0.02
Nam et al. [14]
2015
Korea
0.37
Yao et al. [12]
2013
China
0.03
Matsuura et al. [15]
2013
Japan
0.03
Tan et al. [11]
2012
Singapore
0.04
Lin et al. [16]
2011
China
0.01
Al-Mezaine et al. [17]
2009
Saudi Arabia
0.07
Wu et al. [18]
2006 (a)
Taiwan
0.21
Wu et al. [19]
2006 (b)
Taiwan
0.11
Trinavarat et al. [20]
2006
Thailand
0.22
Wong and Chee [10]
2004 (b)
Singapore
0.08
Nagaki et al. [21]
2003
Japan
0.13
Oshika et al. [22]
2003
Japan
0.05
Causative Organisms
Presentation within 6 weeks of surgery is termed acute and beyond 6 weeks as chronic endophthalmitis. This distinction is helpful because the microbiological spectrum causing acute endophthalmitis differs greatly from that causing chronic endophthalmitis. The most common organisms causing acute postoperative endophthalmitis are predominantly gram-positive especially coagulase-negative Staphylococcus and less commonly gram-negative Enterococcus and Pseudomonas species [10, 11, 29] (Table 4.2). Nam reported that Enterococcus faecalis and Staphylococcus epidermidis were the most common organisms in their series from Korea, but they included infectious endophthalmitis following trauma, corneal and scleral laceration, intraocular foreign body, and endogenous endophthalmitis [14].
Table 4.2
Causative organisms in postoperative endophthalmitis in Asia
Author | Year | Country | Coagulase-negative staphylococci | Staphylococcus aureus | Streptococcus species | Enterococcus | Gram-negative organisms | Fungi |
|---|---|---|---|---|---|---|---|---|
Yao et al. [12] | 2006–2011 | China | 32% | 12% | 4% (S. pyogenes) | 1% | 11% | 0% |
4% (S. viridans) | ||||||||
Falavarjani et al. [29] | 2006–2011 | Iran | 38.8% | 0% | 0% | 0% | 43.1% | 1.5% |
Cheng et al. [30] | 2002–2008 | Taiwan | 1% | 8% | 0% | 4% | 19% | 0% |
Kim et al. [31] | 2000–2007 | Korea | 67% (S. epidermidis) | 11% | 11% | 11% | 0% | 10% |
Jung et al. [32] | 2001–2006 | Korea | 28% (S. epidermidis) | 0% | 28% | 0% | 17% (Enterobacter sp.) | 0% |
17% (P. aeruginosa) | ||||||||
Wong and Chee [10] | 1996–2001 | Singapore | 57% | 10% | 14% | 0% | 5% (P. aeruginosa) | 0% |
14% (other gram-negative) | ||||||||
10% (Serratia marcescens) | ||||||||
33% (Serratia marcescens) |
The infecting organism predicts the visual prognosis. Eyes with coagulase-negative Staphylococcus endophthalmitis and culture-negative endophthalmitis have a better prognosis and are more likely to achieve a better final visual acuity of 20/40 [10]. On the contrary, Pseudomonas aeruginosa endophthalmitis tends to result in poorer visual outcomes, with 71% of eyes having final visual acuity of no light perception (NLP) and 50% requiring evisceration [33].
Clinical Features
Postoperative endophthalmitis typically presents within the first postoperative week in approximately two thirds (61%) of cases [34]. Symptoms include eye pain and redness with reduced visual acuity in 75–95% of cases [34]. An afferent pupillary defect may be present in 12%, and eyelid edema, conjunctival injection and chemosis, corneal edema, and anterior chamber inflammation and fibrin accumulation can be observed. A hypopyon is present in up to 86% of cases, and the red reflex is absent in 67% [34] (Fig. 4.1). Other signs include vitritis, Roth spots, vascular sheathing, retinitis, papillitis, and proptosis if it progresses to panophthalmitis.
Fig. 4.1
(a) A 57-year-old male patient presented with acute postoperative endophthalmitis on postoperative day 5 after phacoemulsification, in-the-bag intraocular lens implant, and capsular tension segment fixation for a right subluxated cataract. Note the congested eye and hypopyon. (b) Dense vitritis with hand movement visual acuity with no afferent pupillary defect
Prognostic Factors
Eyes with presenting visual acuity of counting fingers (CF) or better and eyes that do not require pars plana vitrectomy are more likely to have a final visual acuity of 20/40 or better [10]. Intraoperative posterior capsule rupture and the use of silicon intraocular lens [10, 12, 13, 35] have been reported to be significant risk factors for endophthalmitis. For unknown reasons, phacoemulsification technique has been observed to have a higher risk of endophthalmitis compared to extracapsular cataract extraction, although some other studies do not concur [7, 36]. The use of intracameral cefazolin (1.0 mg/0.1 mL) or cefuroxime (1.0 mg/0.1 mL) has been reported to decrease the rate of endophthalmitis [11, 13], and the incidence of endophthalmitis has also been lowered with prophylactic use of intracameral vancomycin (0.1 mg in 0.1 mL of normal saline) and tobramycin (16 mg/L of irrigation solution) [12]. The associations with age and gender remain controversial [10, 11, 13, 14].
Bleb-Related Endophthalmitis
Bleb-related infections can complicate glaucoma filtration surgery, especially following filtering surgeries with adjunctive mitomycin C with a reported incidence of 1.5% at 2.5 years of follow-up [37]. The most common pathogens identified in bleb-related infections in a prospective multicenter study in Japan were Streptococcus species, coagulase-negative Staphylococcus, Haemophilus influenzae, and Enterococcus species among cases with stage IIIb endophthalmitis manifesting with advanced vitreous involvement [38]. Pseudophakic or aphakic eyes tend to be associated with more advanced infection. These cases are associated with deterioration of visual acuity 12 months following the infection—an increase in logMAR visual acuity of at least 0.5 units [39].
Risk Factors
Leaking bleb is a significant predisposing factor for bleb-related endophthalmitis. An inferior quadrant-positioned trabeculectomy has a high risk of developing endophthalmitis. Other risk factors include eyes treated with 5-fluorouracil [40]; the use of mitomycin C [41]; thin, avascular blebs associated with hypotony; recurrent bleb leakage; pseudophakia; and repeated filtering surgery [42]. The high bleb and blepharitis also increase the risk of endophthalmitis after filtering surgery [41]. In a study from Israel, thin and leaking blebs, long axial length, conjunctivitis, upper respiratory infection, and the winter season were significant risk factors for bleb-related endophthalmitis [43].
Clinical Features
Bleb-related endophthalmitis may present with pain, reduced vision, relative afferent pupillary defect, and hypopyon [43, 44]. Prodromal symptoms such as browache, headache, external eye infection, or inflammation have been observed in previous visits before the onset of bleb-related endophthalmitis [42, 43]. In a study from Saudi Arabia, 89.3% of patients with bleb-related endophthalmitis presented with eye redness, 81.3% had pain, and 22.7% had purulent discharge [45]. The condition may present early within 15 days following surgery or delayed for up to 30 years following filtering surgery [46, 47].
Endophthalmitis After Keratoplasty
The incidence of endophthalmitis post-penetrating keratoplasty is 0.1–0.7% [48]. The predominant pathogens are gram-positive organisms [49]. However, the clinician must also consider fungal pathogens such as Candida albicans or Candida parapsilosis in the presence of progressive intrastromal opacities around corneal incisions and intraocular inflammation [50].
Endophthalmitis has been reported in 6% (2 of 36 cases) of cases with osteo-odonto-keratoprosthesis (OOKP) surgery. But the case series was small, and one of the cases had endophthalmitis following endoscopic transscleral cyclophotocoagulation a full year after successful OOKP surgery, and the infection was not a direct consequence of OOKP surgery [51].
Endophthalmitis After Intravitreal Injections
Intravitreal injections are now commonly performed for patients with vitreoretinal pathology such as age-related macular degeneration, diabetic maculopathy, and retinal vein occlusion. Several case series have been reported from Asia. The incidence of acute endophthalmitis after intravitreal injections (both in the West and in Asia) ranges from 0.01% to 0.10% [52–55].
Post-traumatic Endophthalmitis
Post-traumatic endophthalmitis may complicate open-globe eye injury. The incidence ranges from 2.1% to 5.1% [56, 57]. The risk of endophthalmitis is significantly higher among eyes with pure corneal injuries, intraocular foreign bodies, traumatic lens rupture, and trauma resulting from needles [57, 58]. Infection by Bacillus species (in approximately 25%) can result in rapidly progressive endophthalmitis with a high risk of visual loss due to the destruction caused by cytolysins and enzymes produced by the bacteria [59–61]. Other commonly isolated bacteria include coagulase-negative staphylococcal species such as Staphylococcus epidermidis and Staphylococcus saprophyticus, Bacillus subtilis, Pseudomonas aeruginosa, and Escherichia coli. The most commonly isolated fungus is Aspergillus [62]. Bacillus cereus is a major causal organism in post-traumatic cases with poor visual outcome [63].
Chronic Postoperative Endophthalmitis
Chronic postoperative endophthalmitis (CPE) is a rare complication and occurs more than 6 weeks to years after the initial event [64, 65]. The patient typically presents with persistent low-grade anterior chamber inflammation with a characteristic white plaque on the posterior lens capsule and decreased visual acuity in the affected eye. Some patients may experience mild pain, and anterior vitreous inflammation is common [66].
The most common isolated organism in CPE cases is Propionibacterium acnes [67], but there are reports of other rare causative indolent organisms such as Ochrobactrum anthropi [68], Massilia timonae [69], Mycobacterium manitobense [70], Acinetobacter calcoaceticus [71], Torulopsis candida [72], Corynebacterium minutissimum [73], and Alcaligenes xylosoxidans [74]. With the advent of polymerase chain reaction (PCR), sequencing-based pathogen identification in addition to routine culture methods helps in identifying the microorganisms. Scanning electron microscopy and PCR techniques have demonstrated the adherence of bacteria on the surface of explanted intraocular lens and capsular bags [67, 75].
Endogenous Endophthalmitis
Endogenous endophthalmitis is a rare metastatic ocular infection which can affect both previously healthy and immunocompromised individuals [76]. The medical conditions commonly associated with this are diabetes mellitus, hepatobiliary disease, liver cirrhosis, and malignancy [77–79]. Other underlying associated conditions include renal failure, indwelling catheters, immunosuppressive diseases, recent surgery, endocarditis, and intravenous drug abuse [76, 80, 81]. Up to 77% have an identifiable causative risk factor [77], and it can affect patients of any age and gender. In Asia, pyogenic liver abscess (PLA) is the most common source [77], and other sources include pneumonia, osteomyelitis, urinary tract infection, soft tissue infection, peritonitis, septic arthritis, catheter-related infection, infective endocarditis, and meningitis [79]. However, the source may remain unidentifiable in up to 7.4–35% of patients despite extensive systemic investigations.
Causative Organisms
Gram-positive bacteria such as Staphylococcus aureus and Streptococcus pneumoniae have been reported to be the most common causative organisms of endogenous endophthalmitis in the West [76, 82]. However, the gram-negative bacteria such as Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa are reported to be responsible for the majority of endogenous endophthalmitis in many case series from Asia [77–79, 81]. Other causative organisms such as Bacillus cereus endophthalmitis among intravenous drug abusers, Haemophilus influenzae and Neisseria meningitides endophthalmitis among pediatric individuals, and Nocardia asteroides and Mycobacterium tuberculosis endophthalmitis are also reported as rare cases in Asia [80].
Among East Asians, Klebsiella pneumoniae has been reported as a common cause of endogenous bacterial endophthalmitis, accounting for approximately 60% of all cases [81, 83]. Hepatobiliary tract infection is a major source of bacteremia (45–62%) [83]; there is a 3.0–7.8% risk of developing endophthalmitis among patients with liver abscess [84–86]. Incidence of endophthalmitis after PLA was estimated to be 0.84%, with a hazard ratio of 12.83 (95% confidence interval 8.94–18.41) compared to patients without PLA [87]. Among patients with liver abscess, diabetes mellitus was reported as a risk of endophthalmitis development and poorer visual outcome [80]. Other reported risk factors include disseminated intravascular coagulation and delayed diagnosis and treatment [81, 83, 88–90]. The interval between the diagnosis of liver abscess and endophthalmitis was approximately 3.12–4.4 days; 4.9–19% of patients presented with ocular symptoms before the diagnosis of sepsis and liver abscess were confirmed [91, 92]. This condition can also affect individuals with no underlying illness or known immunocompromised conditions in 41% of patients [92]. Less commonly, Klebsiella pneumoniae endophthalmitis can also arise from renal abscess in diabetic patients [93].
Pseudomonas aeruginosa infection can also present as endogenous endophthalmitis although it is more commonly related to infective keratitis, scleritis, or postsurgical endophthalmitis [33]. Besides gram-negative organisms, gram-positive organisms such as Staphylococcus aureus, Streptococcus pneumoniae, group B Streptococcus, and Staphylococcus epidermidis are most frequently spread from infective endocarditis and skin, bone, and joint infections [79]. One third of the patients may have an underlying chronic disease, such as diabetes mellitus, underlying malignancy, or acquired immunodeficiency syndrome, but group B Streptococcus endophthalmitis can also affect healthy individuals. A reverse relative afferent pupillary defect, sliding hypopyon, and diffuse panophthalmitis can often be observed at presentation as a result of its rapid, widespread destruction of the choroid and retina [94].
Serratia marcescens has been reported to cause irido-lenticular abscess from endogenous endophthalmitis as a result of nosocomial infections in susceptible immunocompromised individuals [95, 96]. Patients can present with intractable pain and angle closure, and high-frequency ultrasound biomicroscopy is needed to detect ciliary body abscesses that may be missed by B-scan ultrasonography. This is an aerobic, gram-negative bacillus that is commonly associated with respiratory and catheter-related bacteremia in susceptible individuals.
Clinical Features
Presenting symptoms of endogenous endophthalmitis are similar to that of postoperative endophthalmitis: ocular pain, reduction of vision, and eye redness [91, 92]. However, certain features have been reported to be characteristic of certain causative organisms, such as a “pupillary hypopyon” with fibrous obscuring the pupil among cases with Klebsiella pneumoniae [92], a “sliding hypopyon” among cases with group B Streptococcus, and a pink or dark hypopyon with Serratia infection. The majority was unilateral although 14–25% of cases may have bilateral involvement [76, 81]. Most patients (up to 87%) had poor visual acuity at presentation (worse than 4/200) [92], and septicemia or an extraocular focus of infection was often present before the presentation of visual symptoms.
Gram-negative organisms commonly present with focal whitish nodules within the choroids or choroidal abscess with rapid involvement of the retina (Fig. 4.2). Intense vitritis is often seen in diffuse severe disease with poor fundal view. Perivascular hemorrhages, inflammatory infiltrates, and arterial emboli may be observed [80]. Frank retinal necrosis and globe perforation at the site of an abscess may also occur. In contrast, gram-positive organisms may be multifocal with Roth spots and retinal vasculitis.
