Endophthalmitis

Endophthalmitis is uncommon but requires emergency treatment because infection inside the eye can cause rapid, permanent vision loss. The infection involves the aqueous or vitreous, so inflammation can build quickly and vision can be lost in days. The most common setting is recent intraocular surgery, especially cataract surgery, or an intravitreal injection. It can also follow an open globe injury, spread from a severe corneal ulcer, or, more rarely, arrive through the bloodstream.

When to Worry After Eye Surgery or Injection

Patients who have just had cataract surgery, an intravitreal injection, or other intraocular surgery should be alert for the warning signs of endophthalmitis. The classic symptoms can appear from a few hours after surgery to several weeks later:

Symptoms

• Pain - increasing rather than improving after surgery or trauma; often described as deep, aching
• Vision loss ranging from blur to severe; rapidly progressive in acute bacterial endophthalmitis
• Red eye with conjunctival injection
• Photophobia
• Floaters - increasing or new
• Eyelid swelling in some cases
• Hypopyon - a layer of white inflammatory cells settling at the bottom of the anterior chamber, visible to the doctor and sometimes to the patient as a white line in the eye
• Decreased red reflex - the inside of the eye looks dim or hazy on examination

Types

Endophthalmitis is classified by the source of infection. The type drives both the likely organisms and the treatment.

Acute Postoperative

Onset within 6 weeks of intraocular surgery (the EVS definition); most virulent acute cases present in the first 1-2 postoperative weeks. The most common scenario.

• Cataract surgery - most common. Reported modern incidence is approximately 0.02-0.1% per case, with rates at the lower end (around 1 in 2,000 to 1 in 5,000) at centers using intracameral antibiotic prophylaxis.
• Intravitreal injection - anti-VEGF or steroid implant injections; very low per-injection rate but volume-driven.
• Penetrating keratoplasty (corneal transplant), trabeculectomy, vitrectomy, and other intraocular procedures.

Most commonly caused by skin and conjunctival flora - coagulase-negative Staphylococcus, Staphylococcus aureus, and various Streptococcus species. Streptococcus species and gram-negative organisms tend to be more aggressive.

Delayed-Onset Postoperative

Onset 6 weeks or more after surgery. Typically caused by less virulent organisms walled off behind the iris or in the capsular bag.

• Cutibacterium acnes (formerly Propionibacterium acnes) - classic late-onset bacterial cause after cataract surgery
• Fungi - Candida, less commonly Aspergillus

Presentation is often more indolent - a slowly progressive uveitis-like picture that does not respond to topical steroids and that may have a characteristic white plaque on the lens capsule.

Bleb-Associated

Late infection in eyes with filtering blebs from glaucoma surgery (e.g., trabeculectomy). Can occur years after the original surgery. Often caused by Streptococcus, Haemophilus, and gram-negative organisms; enterococci are also reported. The course can be rapid and visually devastating.

Post-Traumatic

Following open globe injury. Higher risk with retained intraocular foreign bodies, organic matter contamination (soil, vegetable matter), or delayed primary repair. Often polymicrobial. Bacillus species are notable for their virulence in this setting.

Endogenous (Hematogenous)

Spread to the eye from the bloodstream. Uncommon but serious. Risk factors:

• IV drug use
• Indwelling vascular catheters
• Immunocompromise (chemotherapy, HIV, transplant)
• Diabetes
• Recent abdominal or urinary tract infection
• Liver abscess (notably Klebsiella pneumoniae in East Asia)

Endogenous endophthalmitis is often fungal in immunocompromised hosts, frequently Candida albicans. Bacterial causes vary by region and host: in Western populations, gram-positive cocci (Staphylococcus aureus, Streptococcus) predominate; in East Asia, Klebsiella pneumoniae (often arising from a liver abscess in patients with diabetes) is the leading bacterial cause.

Microbial Keratitis Progressing to Endophthalmitis

Untreated severe corneal ulcers can perforate or extend into the eye, particularly in contact lens wearers with Pseudomonas or fungal keratitis.

Diagnosis

Clinical Examination

The diagnosis is clinical and the threshold for treatment is low. The doctor performs:

• A focused history - recent eye surgery or injection, dates and details; recent trauma; systemic illness, IV drug use, indwelling lines
• Visual acuity - typically reduced; counting fingers or hand motions in severe cases
• A slit lamp examination - anterior chamber cells, flare, fibrin, hypopyon, keratic precipitates, wound integrity, and bleb evaluation
• Vitreous examination - vitritis (cloudy vitreous) is the central finding
• Intraocular pressure measurement
• Dilated fundoscopic exam when the view permits

Diagnostic Sampling

Samples of aqueous and vitreous are obtained for Gram stain, culture, and often PCR testing. Sampling and treatment usually happen at the same time:

• Vitreous tap - needle aspiration of vitreous
• Vitrectomy - surgical removal of vitreous, providing a larger sample and immediate clearance of infectious material

B-Scan Ultrasound

Used when the view to the back of the eye is obscured by media opacity. Shows vitreous opacities, retinal detachment, and any retained foreign body in trauma.

Systemic Workup

For endogenous endophthalmitis, blood cultures, urinalysis and urine culture, evaluation for sources (echocardiogram, abdominal imaging), and an infectious-disease consultation are routine.

Treatment

The cornerstone of treatment is intravitreal antibiotic injection delivered as soon as the diagnosis is suspected. The Endophthalmitis Vitrectomy Study (EVS) established many modern principles although practice has evolved.

Intravitreal Antibiotics (Immediate)

• Vancomycin for gram-positive coverage
• Ceftazidime for gram-negative coverage; an alternative gram-negative agent is selected when ceftazidime is not appropriate
• Antifungal (e.g., voriconazole) when fungal cause suspected, particularly in endogenous and post-traumatic settings

Vitrectomy

• In the landmark Endophthalmitis Vitrectomy Study (EVS), immediate pars plana vitrectomy improved outcomes only in eyes presenting with light-perception-only vision; eyes with hand motions or better had equivalent outcomes with vitreous tap and intravitreal antibiotics alone.
• With modern small-gauge instrumentation, many surgeons now extend vitrectomy to less severe presentations and to non-post-cataract scenarios (e.g., post-trauma, endogenous, or virulent organisms).
• Provides immediate debulking of infection and a larger sample for diagnosis
• Reduces concentration of inflammatory mediators

Adjunctive Therapy

• Topical antibiotics for surface coverage
• Topical and sometimes systemic steroids to control inflammation, after antibacterial coverage is established. Some surgeons also give intravitreal dexamethasone at the time of antibiotic injection; the role of intravitreal steroid remains under investigation
• Systemic antibiotics for endogenous, post-traumatic, and bleb-associated cases
• Cycloplegic drops for comfort and to prevent posterior synechiae

Source Control

• Wound revision if a leaking surgical wound is identified
• Bleb revision in bleb-associated cases
• Removal of intraocular foreign bodies in trauma

Prognosis

Outcomes depend heavily on the organism, the time to treatment, and the type of endophthalmitis:

• Coagulase-negative Staphylococcus - usually the best prognosis among bacterial causes
• Streptococcus and gram-negative species - worse outcomes
• Bacillus species in trauma - devastating; rapid progression often occurs despite treatment
• Fungal - may respond well if recognized early; chronic progressive disease without recognition
• Endogenous - often poor; the systemic illness drives much of the prognosis

Even with appropriate treatment, many patients with severe endophthalmitis lose substantial vision in the affected eye. Some retain useful or excellent vision, particularly when the organism is low-virulence and treatment is prompt.

Prevention

Around Surgery and Injection

• Topical povidone-iodine to the conjunctival surface immediately before any intraocular procedure - strong evidence for risk reduction
• Sterile draping, eyelid speculum, and avoidance of contact between the lid margin and the surgical instruments
• Intracameral antibiotic (e.g., moxifloxacin or cefuroxime) at the conclusion of cataract surgery - substantially reduces postoperative endophthalmitis incidence
• Clear postoperative instructions and same-day access for unexpected pain, redness, or vision decline; topical antibiotic-drop practices vary by procedure and surgeon

After Surgery or Injection

• Clear post-procedure instructions
• Same-day evaluation if pain or vision changes occur

Trauma Prevention

• Eye protection during high-risk activities (yardwork, machining, hammering, sports)
• Prompt evaluation of any penetrating injury

Endogenous Risk Reduction

• Catheter care
• Prompt evaluation of bloodstream infections in immunocompromised hosts
• Treatment of identified systemic sources before they seed the eye

Frequently Asked Questions

How quickly can endophthalmitis cause permanent damage?

Hours to days, depending on the organism. Aggressive organisms like Streptococcus, gram-negatives, and Bacillus can cause profound vision loss within 24 hours of symptom onset. This is why anyone who has had recent eye surgery or trauma and develops worsening pain and vision is urged to seek same-day evaluation.

Will I lose vision in my eye even with treatment?

Many patients lose some vision; some retain excellent vision. The degree of loss depends most on the organism, the time to treatment, and the severity at presentation. Coagulase-negative staphylococcal cases treated promptly often preserve substantial vision; Streptococcus and Bacillus cases frequently do not.

How is endophthalmitis prevented during cataract surgery?

The two strongest evidence-based measures are povidone-iodine prep of the conjunctival surface immediately before surgery and, in many cataract-surgery protocols, intracameral antibiotic at the end of the case. Modern aseptic technique and clear postoperative instructions complete the picture. The risk after typical modern cataract surgery is very low, but rates vary by setting and protocol.

Can endophthalmitis happen without surgery?

Yes. Endogenous endophthalmitis arises from bloodstream infection and can affect anyone, although it is more common in IV drug users, immunocompromised patients, and those with indwelling catheters. Severe untreated corneal ulcer can also progress into the eye, particularly with Pseudomonas or fungal keratitis.

Is endophthalmitis the same as cellulitis?

No. Cellulitis is a soft-tissue infection of the eyelid (preseptal) or orbit (orbital). Endophthalmitis is an infection inside the eye itself. They occur in different locations, are caused by different organisms in different settings, and require different treatments - though severe orbital infection can occasionally extend through the eye wall and produce both.

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