This is the inflammation of the intraocular space occupied by the vitreous. When the inflammation spreads throughout the globe and involves all the layers ± the peri-ocular tissues, it is known as panophthalmitis, a devastating fulminant condition with a very bleak outlook. Endophthalmitis may be endogenous (or metastatic, eg spread of organisms from endocarditis) or exogenous (eg following penetrating ocular trauma). Furthermore, it may be acute or follow a chronic course, depending on the infecting pathogen.
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Normally, the blood-ocular barrier prevents invasion from infective organisms but if this is breached (directly through trauma or indirectly due to a change in its permeability secondary to inflammation), infection can occur. Endophthalmitis can be:
- Associated with surgery: acute or delayed postoperative, bleb-associated.
- Traumatic: bacterial or fungal endophthalmitis.
- Endogenous: bacterial or fungal endophthalmitis.
- Associated with corneal infection (microbial keratitis).
This is a rare condition. Most cases of exogenous endophthalmitis are postoperative, occurring after about 0.1% of cataract procedures. Patients aged over 85 who have had cataract surgery seem to be particularly prone.
In a large Chinese study, post-traumatic endophthalmitis occurred in 11.1% of open-globe injuries.
Endogenous endophthalmitis is even rarer than exogenous endophthalmitis (approximately 2-15% of all endophthalmitis cases). One American study reported an average annual incidence of 5 in 10,000 hospitalised patients.
- In nonaccidental injury (surgery): previous presence of infection (eg bacterial conjunctivitis), poor surgical technique and contaminated intraocular lens.
- In accidental injury: retained infected foreign material, particularly if this is organic.
- Ophthalmic risk factors: contact lens wear (where there is poor hygiene) or chronic corneal ulceration.
- Non-ophthalmic risk factors: debility, distant infection (eg indwelling catheter) , immunosuppression, intravenous drug use, AIDS.
- A red eye.
- Decreased vision.
- A history of ocular surgery or trauma, an immunocompromised state or recent distant infection.
Associated with surgery
- Acute postoperative endophthalmitis
- History - this arises one to several days after surgery. There is sudden decrease of vision and increasing eye pain.
- Signs - without the slit lamp, you may see lid oedema, intense conjunctival injection and chemosis and you may spot a hypopyon (pus in the anterior chamber, which looks like a white fluid level sitting at the base of the iris). The red reflex is decreased. Slit-lamp examination will reveal severe inflammation in the anterior chamber and the vitreous.
- Delayed postoperative endophthalmitis
- History - this develops a week to a month (or more) after surgery. It may even take years to develop but the average is 9 months. There is insidious decrease of vision and gradually increasing redness and minimal or no pain.
- Signs - without the slit lamp, look for conjunctival injection, a hypopyon and you may just see clumps of exudate (little white blobs) in the anterior chamber, on the iris or around the pupillary margin. The cornea may look cloudy (due to oedema). These signs are clearly seen with the slit lamp, as are the anterior chamber and vitreous inflammatory reactions.
- Bleb-associated endophthalmitis
- When drug therapy fails in the treatment of glaucoma, patients may go on to have surgery. A trabeculectomy is a procedure that creates a fistula which allows the aqueous to drain from the anterior chamber. A so-called bleb is formed over this area, seen as a smooth, raised patch just above the cornea, under the upper lid. Occasionally, this gets infected ('blebitis') but when the vitreous is also involved, it becomes a bleb-associated endophthalmitis.
- There is a short history of rapidly worsening pain and vision, with marked redness, and the bleb itself will appear milky white. There may be a hypopyon too.
Not associated with surgery
- Traumatic endophthalmitis
The signs are the same as with acute postoperative endophthalmitis. Some organisms (eg Bacillus spp.) may result in a severe reaction and lead to pyrexia, leukocytosis, proptosis and a corneal abscess.
- Endogenous bacterial endophthalmitis
Decreased vision in an acutely ill patient should prompt thoughts of endogenous bacterial endophthalmitis. It also typically occurs in an immunocompromised individual or intravenous (IV) drug user. Staphylococcus aureus is the most common organism involved, followed by Streptococcus pneumoniae and Streptococcus viridans. Gram-negative organisms such as Escherichia coli can also be a cause. Signs may include lid and conjunctival oedema and the cornea may appear cloudy. Ophthalmoscope examination may also reveal flame-shaped retinal haemorrhages. If slit-lamp examination is possible, you may see hypopyon, an anterior chamber and vitreous inflammatory reaction and microabscesses on the iris. Panophthalmitis may ensue.
- Candida-associated endophthalmitis
This may arise in similar conditions to endogenous bacterial endophthalmitis. It should also be suspected where there is a history of a penetrating injury with an organic foreign body (eg plant or soil-contaminated object). Surprisingly, there appears to be no association with AIDS or any other immunocompromised condition. There is, however, an association with abdominal surgery and there is a theory that candidal overgrowth is involved. Diabetes is another risk factor and an increase in vitreous glucose has been identified in patients with candidal endophthalmitis. Symptoms include decreased vision, floaters and pain. It is usually bilateral and may follow an indolent course. Ophthalmoscopy will reveal fluffy yellow-white retinal lesions (which look a bit like cotton balls) ± retinal haemorrhages. If you can examine the patient with a slit lamp, you will see widespread inflammation and a hypopyon.
- Other fungal endophthalmitis
Candida is by far the most common cause of fungal endophthalmitis but other fungi are occasionally found - notably Aspergillus spp. (found in soil, decaying matter and organic debris) cryptococci (notably found in pigeon droppings) and the Coccidioides spp. (agricultural and construction workers are at risk). These remain rare infections although the incidence is increasing, possibly related to IV drug use, the use of chemotherapy in cancers and immunosuppressive therapy in transplant patients, as well as the increasing survival of debilitated patients. Presenting features are as for the other forms of endophthalmitis but visual loss may be less significant.
- Endophthalmitis associated with microbial keratitis
The cornea can become infected in a variety of situations, particularly in contact lens wear (high risk factors include extended wear and poor hygiene), where there is pre-existing corneal disease and, occasionally, in other conditions (eg chronic blepharoconjunctivitis or dacrocystitis, tear film deficiency or topical steroid therapy). If this is severe, there may be progressive ulceration of the cornea which can lead to a bacterial endophthalmitis. Such patients are usually already under the care of an ophthalmic team.
There are a number of causes of red eye postoperatively, including:
- Raised intraocular pressure as a direct result of the procedure.
- Retained lens material - if the crystalline lens is not fully removed at the time of cataract surgery, the small remaining piece can cause an intraocular inflammatory reaction. This is an autoimmune reaction to the exposed lens protein. The lens material can often be seen with a slit lamp if the patient is asked to move their eyes (it is seen floating up in the aqueous or vitreous before settling down again when the eye is still).
- Aseptic endophthalmitis is more likely to occur after a prolonged procedure and results from excessive tissue manipulation. Symptoms and signs are usually mild.
- Inflammatory reactions can occasionally occur in response to the substances used in cataract surgery (eg those used to sterilise the intra-ocular lens).
- In immunocompromised host where there might be fungal endophthalmitis, other differentials include cytomegalovirus retinitis, toxoplasmosis and a number of other conditions that have similar lesions and that will be assessed by the ophthalmologist (eg infections with herpes simplex, nocardia, aspergillus and cryptococci).
Remember that postoperative and trauma patients can also develop a red eye due to a new problem that is unrelated to the procedure or trauma.
See separate article Red Eye for fuller discussion of the general causes of this condition.
Initial diagnosis is made on slit-lamp examination. An ultrasound scan (easily and painlessly performed in the outpatient clinic) may also be of help. However, diagnosis is ultimately confirmed by taking a sample of vitreous for microbiological culture (diagnostic surgical vitrectomy). This is done in theatre and may also be a therapeutic procedure if the vitreous is entirely removed (to reduce the infectious load); intraocular antibiotics can be administered at the same time.
In the case of endogenous bacterial endophthalmitis and candida-associated endophthalmitis, a full infection screen is warranted (FBC, blood cultures and culture of all indwelling lines and catheters). The latter may also prompt a search for possible immunocompromise.
Polymerase chain reaction (PCR) may be helpful in differentiating between fungal and bacterial infection.
Other investigations may be required to exclude differential diagnoses (eg erythrocyte sedimentation rate (ESR) to help rule out rheumatoid arthritis) and associated conditions (eg creatinine to assess renal function).
CT or MRI scan of the orbit may help to rule out other ophthalmic conditions.
These are different depending on the type of endophthalmitis as discussed above in 'Risk factors' and 'Presentation'.
- If you suspect acute endophthalmitis, immediate same day/night referral is mandatory. If you suspect a delayed postoperative endophthalmitis, refer within 24 hours.
- The subsequent management depends on the type of endophthalmitis. All but a very few patients will be admitted for a diagnostic work-up (see 'Investigations', above) and antimicrobial treatment.
- Some patients will additionally be prescribed steroids once fungal infection has been ruled out. These are to limit the amount of inflammatory-induced damage.
- Topical cycloplegics also play a role in controlling the symptoms.
- Some patients will need surgery: vitreous aspiration or a vitrectomy (removal of the vitreous) may be indicated. In addition to providing material for microbiology, it reduces infective load.
- Trauma cases also need tetanus immunisation if this is not up-to-date.
These are mainly decrease or loss of vision. Chronic pain may become an issue in some patients.
The visual acuity at the time of the diagnosis and the causative agent are most predictive of outcome. As a rule of thumb, endogenous endophthalmitis has a worse prognosis than exogenous endophthalmitis and some patient groups such as diabetics do less well. Acute postoperative endophthalmitis has a poor prognosis with 55% of eyes managing 6/60 or less. Chronic postoperative endophthalmitis usually responds well to steroids initially but then tends to become refractory to treatment. One study found that 74% of patients after vitrectomy had a visual acuity of 6/30 or better. Successfully treated bleb-associated endophthalmitis is at risk of recurring infections. In the event that vision is lost and the eye becomes chronically painful, enucleation (removal of the globe) may have to be considered.
Optimum prophylaxis in acute postoperative endophthalmitis has yet to be determined. However, good management of pre-existing infections and meticulous pre-operative preparations do reduce the risks.
A note on sympathetic ophthalmia
This is an inflammatory condition affecting both eyes that occurs after a penetrating injury (accidental or surgical) to one of the eyes. See separate article Sympathetic Ophthalmia for more details.
Further reading & references
- Egan DJ et al; Endophthalmitis, eMedicine, Apr 2009
- Zhang Y, Zhang MN, Jiang CH, et al; Endophthalmitis following open globe injury. Br J Ophthalmol. 2010 Jan;94(1):111-4. Epub 2009 Aug 18.
- Kunimoto DY, Kanitkar KD, Makar MS; The Wills Eye Manual (4th Ed), Lippincott, Williams and Wilkins (2004)
- Taban M et al; Endophthalmitis, Postoperative, eMedicine, Nov 2008
- Wu L et al; Endophthalmitis, Fungal, eMedicine, Feb 2010
- Kanski J. Clinical Ophthalmology; A Systematic Approach (5th Ed) Butterworth Heinemann (2003)
- Chan C; Sympahetic ophthalmia, American Uveitis Society, 2003
|Original Author: Dr Olivia Scott||Current Version: Dr Laurence Knott|
|Last Checked: 26/10/2010||Document ID: 8631 Version: 3||© EMIS|
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