What is Endophthalmitis?
Endophthalmitis is a severe, sight-threatening infection involving purulent inflammation of the intraocular spaces (vitreous and/or aqueous humor) caused by bacterial or fungal pathogens that can result in permanent vision loss or loss of the eye itself if not promptly treated. 1, 2
Pathophysiology and Routes of Infection
Endophthalmitis occurs through two distinct mechanisms 1:
Exogenous endophthalmitis: Pathogens are introduced directly into the eye from external sources following trauma, ocular surgery (including cataract surgery, intravitreal injections), or as an extension of corneal infection (keratitis) 1, 2
Endogenous endophthalmitis: Pathogens reach the eye via hematogenous spread across the blood-eye barrier during bacteremia or fungemia from distant infection sites 1, 3, 4
Clinical Significance and Outcomes
This condition represents a medical emergency requiring immediate recognition and treatment 5, 2:
Vision loss is the most common clinical manifestation, often accompanied by ocular pain, inflammatory findings (hypopyon), and visual changes 5, 6
Untreated or severe endophthalmitis can progress rapidly to corneal perforation and loss of the eye 1
Despite appropriate therapeutic intervention, endophthalmitis frequently results in permanent visual impairment 7
Common Causative Organisms
The spectrum of pathogens varies by mechanism of infection 1, 2:
Exogenous Endophthalmitis:
- Post-operative (cataract surgery): Coagulase-negative staphylococci predominate; chronic cases may involve Propionibacterium acnes 1, 2
- Post-traumatic: Bacillus cereus, environmental gram-negative rods (Pseudomonas aeruginosa), dematiaceous fungi, Fusarium spp, Nocardia spp, Mycobacterium chelonae 1, 2
- Post-intravitreal injection: Coagulase-negative staphylococci and viridans streptococci 2
Endogenous Endophthalmitis:
- Bacterial: Staphylococcus aureus, Streptococcus pneumoniae, Klebsiella pneumoniae (especially in East Asia with liver abscess), Enterobacteriaceae, Pseudomonas aeruginosa 1, 2
- Fungal: Candida albicans and related species (most common), Aspergillus spp 1, 3, 4, 6
Key Clinical Pitfall
All patients with candidemia must undergo dilated retinal examination by an ophthalmologist within the first week of therapy to detect endogenous Candida endophthalmitis, as recommended by the Infectious Diseases Society of America 3, 4. This is critical because endophthalmitis can occur without obvious ocular symptoms initially, and delayed diagnosis significantly worsens visual outcomes.
Treatment Principles
Management requires urgent ophthalmology consultation 5, 2:
- Intravitreal antibiotic or antifungal injection is the most important treatment component 2
- Vitrectomy may be necessary in severe cases 3, 2
- Systemic antimicrobials are indicated for endogenous endophthalmitis and exogenous fungal endophthalmitis 3, 4, 2
- Treatment decisions should be made jointly by ophthalmology and infectious diseases specialists for fungal cases 3, 4