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

Pathology

Aetiology

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

Exogenous causes are more common and 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 ¹.

Radiographic features

Imaging diagnosis can be challenging early in the disease process, with the globe potentially having an unremarkable appearance. As endophthalmitis progresses, abnormal echoes/density/signal will be evident within the vitreous with smooth or irregular thickening and enhancement of the uveoscleral layer⁵ .

Features of panopthalmitis includes: oedema or exudates within the tissues surrounding the sclera, especially in the sub-Tenon's space, extraocular inflammation such as lacrimal gland enhancement and enlargement and subconjunctival abscess. Pre and post-septal stranding indicates orbital cellulitis ^5,6.

Ultrasound

Intraocular echogenic debris, membranes and increased echogenicity of the vitreous humour may be seen, along with chorioretinal thickening. Retinal or choroidal detachments may be present.

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

  • similar to an abscess, this is virtually diagnostic of endophthalmitis

  • decreasing diffusion restriction is thought to correlate positively with treatment response ²

• oedema within the extraocular tissues (an indicator of panophthalmitis)

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.

See also

• orbital infection