Endophthalmitis diagnosis and treatment

Acute Post-Cataract Endophthalmitis

Acute post-cataract endophthalmitis represents a catastrophic purulent intraocular infection involving the vitreous and anterior chambers. The reported incidence across modern European phacoemulsification cohorts ranges between 0.03% and 0.08% (approximately 1 in 1,200 to 1 in 3,000 surgeries). Routine intracameral cefuroxime (1.0 mg in 0.1 mL) prophylaxis at the conclusion of surgery has decreased the incidence five-fold (as demonstrated in the landmark ESCRS multicenter study).

Clinical Presentation and Timing

• Timeline: Characteristically presents between postoperative days 3 and 7 (median onset: day 5). Presentations after 6 weeks are classified as chronic pseudophakic endophthalmitis (typically caused by low-virulence organisms such as Cutibacterium acnes, Corynebacterium, or fungi).
• Primary Source: In $>80\%$ of cases, molecular typing confirms that the infecting organism originates from the patient's own ocular surface flora (eyelashes, eyelid margin, and conjunctival sac) entering the eye during surgery or through an unsealed clear corneal wound in the early postoperative period.
• Symptoms:
  • Rapid, progressive deterioration of visual acuity out of proportion to normal postoperative recovery;
  • Severe, deep, throbbing ocular and periorbital pain (important exam caveat: pain is absent in up to 25% of patients, meaning absence of pain never excludes endophthalmitis);
  • Marked photophobia, eyelid oedema, and red eye.
• Physical Signs:
  • Eyelid oedema and profound conjunctival/ciliary injection;
  • Corneal epithelial and stromal oedema with Descemet folds;
  • Dense anterior chamber cells, fibrin membranes across the pupil/IOL, and a progressive hypopyon;
  • Dense vitritis obscuring retinal vessel architecture and complete loss of the red reflex on distant direct ophthalmoscopy.

Microbiology of Acute Postoperative Endophthalmitis

The Landmark Endophthalmitis Vitrectomy Study (EVS)

EVS studied acute postoperative bacterial endophthalmitis after cataract extraction or secondary-IOL implantation in the 1990s. Immediate vitrectomy benefited eyes with light-perception-only acuity; better-vision eyes had similar outcomes with initial tap/inject and vitrectomy. This is evidence for that population and technology, not a rule that hand-motions acuity forbids modern vitrectomy.

The systemic antibiotics tested did not improve outcomes; that does not establish that every systemic antimicrobial is useless in every endophthalmitis type. Endogenous, fungal, traumatic and bleb-related infections differ and can require systemic therapy, source control or different surgery. Consider pathogen, progression, retinal visibility, lens/capsule infection, pressure and response. Do not delay effective intravitreal treatment awaiting culture or a surgery slot.

Sampling and Intravitreal Treatment

Obtain vitreous and sometimes aqueous samples for microscopy and culture, with molecular tests when indicated. Samples must reach the appropriate laboratory promptly. Coordinate with the vitreoretinal surgeon and microbiologist and document prior antibiotics. A negative culture does not exclude infection.

Common empiric adult intravitreal coverage is vancomycin 1 mg/0.1 mL and ceftazidime 2.25 mg/0.1 mL. Pharmacy preparation, final concentration, syringe labelling and route checks are essential. Give separate syringes according to validated local protocol; a bedside dilution recipe is not adequate quality assurance. Allergy and local susceptibility may require an alternative such as amikacin, whose retinal toxicity risk needs particular care. Intravitreal corticosteroid adjunct evidence is uncertain and does not justify delaying antibiotics.

Follow closely for clinical response, pressure, retinal status and the need for repeat treatment or vitrectomy. Repeated doses are a clinical decision, not dependent only on a positive culture. Inform the patient about prognosis, treatment urgency and possible additional surgery.

Bleb-Associated Endophthalmitis

Bleb-associated endophthalmitis develops as a late, vision-threatening complication following glaucoma filtration surgery (trabeculectomy or express shunt). It can arise months, years, or decades postoperatively (mean onset: 2 to 5 years).

Pathophysiological Risk Factors

• Thin, avascular, transconjunctival, cystic filtration blebs resulting from intraoperative antifibrotic antimetabolites (Mitomycin C [MMC] or 5-Fluorouracil [5-FU]);
• Inferiorly situated trabeculectomy blebs (bathed in contaminated tear film pools);
• Late bleb leaks (positive Seidel test);
• Chronic blepharitis and recurrent conjunctivitis.

Clinical Staging

• Blebitis: A purulent inflamed bleb without established vitreous involvement requires urgent intensive antimicrobial management and close review according to local protocol. Check for a leak and posterior extension; progression to endophthalmitis needs intravitreal treatment and surgical assessment.
• Stage 2 (Bleb-Associated Endophthalmitis): Microorganisms breach the thin conjunctival wall and enter the anterior chamber and vitreous cavity. Presents with severe ocular pain, profound visual loss, dense anterior chamber fibrin, hypopyon, and marked vitritis.
• Microbiology: Aggressive virulent upper respiratory tract and oral commensals: Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Pseudomonas aeruginosa. Visual prognosis is significantly poorer than acute post-cataract endophthalmitis, frequently demanding urgent vitrectomy.

Post-Traumatic Endophthalmitis

Post-traumatic endophthalmitis develops in 3% to 10% of penetrating open-globe injuries, escalating to $>15\%$ in the presence of a retained intraocular foreign body (IOFB).

Key Risk Factors

• Delayed primary surgical wound closure ($>24\text{ hours}$ post-injury);
• Open-globe injury occurring in a rural, farmyard, or soil-contaminated environment;
• Retained intraocular foreign body;
• Traumatic rupture of the crystalline lens capsule.

Microbiology and The Bacillus cereus Emergency

• Bacillus cereus: A spore-forming, Gram-positive rod responsible for up to 25% to 45% of farmyard/soil-contaminated penetrating trauma. It produces powerful necrotising exotoxins (hemolysin, cereolysin) causing fulminant panophthalmitis within 12 to 24 hours of injury. Signs include prostrating pain, high fever, systemic leukocytosis, rapid corneal chemosis and melting, a characteristic ring corneal infiltrate, and gas bubbles in the anterior chamber. Over 80% of affected eyes lose all light perception or require enucleation/evisceration within 24 to 48 hours without immediate intervention.
• Other Pathogens: Coagulase-negative staphylococci, polymicrobial infections, and filamentous fungi (Aspergillus, Fusarium).
• Therapeutic Management: Immediate primary open-globe repair and IOFB extraction, combined with intravitreal vancomycin ($1.0\text{ mg}$) and ceftazidime ($2.25\text{ mg}$). Unlike post-cataract endophthalmitis, systemic intravenous antibiotics ARE indicated (IV vancomycin $1\text{ g}$ q12h + IV ceftazidime $2\text{ g}$ q8h or ciprofloxacin) to prevent orbital cellulitis and extraocular extension.

Endogenous Endophthalmitis

Endogenous endophthalmitis results from the hematogenous dissemination of circulating microorganisms across the blood-retinal or blood-aqueous barrier, establishing metastatic foci within the vascular choroid or retina that subsequently erupt into the vitreous.

Predisposing Risk Factors

• Indwelling central venous lines and total parenteral nutrition (TPN);
• Intravenous drug abuse (IVDU);
• Systemic immunosuppression, chemotherapy, haematological malignancies, and diabetes mellitus;
• Remote septic foci: infective endocarditis, urinary tract infections, pyogenic liver abscesses, or recent major abdominal/pelvic surgery.

Microbiology and Clinical Entities

1. Fungal endogenous endophthalmitis:
   • Candida albicans (most common): Typically occurs in patients with indwelling vascular catheters, TPN, or IVDU. Characterized by focal, fluffy, creamy-white chorioretinal infiltrates at the posterior pole, breaking through the internal limiting membrane to form characteristic spherical vitreous colonies resembling a "string of pearls" or "cotton balls".
   • Aspergillus species: High mortality; observed in organ transplant recipients and profound neutropenia. Produces aggressive, elevated macular subretinal abscesses and extensive vascular thrombosis.
   • Management: High-dose systemic antifungals (IV Voriconazole $400\text{ mg}$ load then $200\text{ mg}$ twice daily, or oral Fluconazole $400\text{--}800\text{ mg/day}$) PLUS Intravitreal Amphotericin B ($5\text{--}10\,\mu\text{g in }0.1\text{ mL}$) or Intravitreal Voriconazole ($100\,\mu\text{g in }0.1\text{ mL}$), combined with early therapeutic pars plana vitrectomy for vitreal involvement.
2. Bacterial Endogenous Endophthalmitis (40–50% of cases):
   • Klebsiella pneumoniae: Highly endemic across East Asia (Taiwan, Korea, Singapore); strongly linked to cryptogenic pyogenic liver abscesses in diabetic patients carrying the hypervirulent K1/K2 capsular serotype. Causes explosive, catastrophic panophthalmitis with subretinal abscesses and high bilateral incidence (up to 25%).
   • Staphylococcus aureus & Streptococcus pneumoniae: Associated with infective tricuspid endocarditis (in IVDU) and pneumococcal meningitis/pneumonia.
   • Management: Comprehensive systemic sepsis workup (blood cultures $\times 3$, echocardiography, abdominal ultrasound/CT, urine culture), high-dose intravenous systemic antimicrobial therapy directed at the primary source, accompanied by immediate intravitreal vancomycin + ceftazidime and early vitrectomy.