Endophthalmitis

Endophthalmitis (plural: endophthalmitides) is a potentially sight-threatening condition that involves intraocular inflammation of any cause. It is distinguished from panophthalmitis in that it does not extend beyond the sclera. It is either infectious or non-infectious in etiology, but in clinical practice, intraocular infections are the commonest cause.

Clinical presentation

Eye pain and discomfort are common presenting symptoms, sometimes accompanied by blurred vision. Physical examination can reveal swollen eyelids, chemosis, conjunctival injection, corneal edema, reduced red reflex, reduced visual acuity and raised intraocular pressure. Diagnosis is frequently made clinically, in most cases, based on these features.

Pathology

Etiology

Bacterial endophthalmitis has been classified as exogenous or endogenous depending on the cause.

Exogenous causes frequently include:

• ocular surgery
• penetrating injury
• spread of periocular infection, i.e. orbital cellulitis

Endogenous cases comprise only 2-7% of endophthalmitis cases and involve haematogenous seeding of intraocular infection from a primary source .

Radiographic features

CT

Often shows non-specific features including:

• proptosis (due to raised intraorbital pressure)
• intraorbital fat stranding
• scleral thickening
• choroidal enhancement post-contrast: often in early disease
• hyperdensity of the vitreous humor

MRI

• areas of high FLAIR signal in the vitreous humor
• T1 isointensity or hyperintensity of the vitreous depending on the proteinaceous content
• restricted diffusion on DWI
  • similarly to an abscess, this is virtually diagnostic of endophthalmitis
  • a decreasing diffusion restriction is thought to correlate positively with treatment response
• edema within the extraocular tissues

Treatment and prognosis

Intravitreal antibiotics are the mainstay of treatment. Vitreal aspiration can be performed to identify the causative pathogen. Severe cases may require surgery with vitrectomy and debridement.