Endophthalmitis

Endophthalmitis is a potentially sight-threatening condition that involves intraocular inflammation of any cause. It is distinguished from panopthalmitis in that is does not extend beyond the sclera. It is either infectious or noninfectious in aetiology, but in clinical practice, intraocular infections are the commonest. 

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 oedema, reduced red reflex, reduced visual acuity and raised intraocular pressure. Diagnosis is frequently made clinically, in most cases, based on these features.

Pathology

Bacterial endophthalmitis has been classified as exogenous or endogenous depending on the cause. Exogenous causes frequently include ocular surgery, penetrating injury or 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. ¹

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 humour

MRI

• areas of high FLAIR signal in the vitreous humour
• 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 ²
• oedema 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.