Most cases of endophthalmitis are caused by gram-positive bacteria, such as Staphylococcus epidermidis or S. aureus. Endophthalmitis caused by gram-negative organisms tends to be more virulent and has a worse prognosis. Fungal and protozoan causes of endophthalmitis are rare. Most cases occur after intraocular surgery (exogenous) or penetrating ocular trauma. Less commonly, infection reaches the eye via the bloodstream after systemic surgery or dental procedures or when IV lines or IV drugs are used (endogenous). (See also Overview of Uveitis.)
Endophthalmitis is a medical emergency because vision prognosis is directly related to the time from onset to treatment. Rarely, untreated intraocular infections extend beyond the confines of the eye to involve the orbit and CNS.
Exogenous endophthalmitis typically causes severe ocular ache and decreased vision. Signs include
Diagnosis requires a high index of suspicion in at-risk patients, especially those with recent eye surgery or trauma. Gram stain and culture of aspirates from the anterior chamber and vitreous are standard. Patients with suspected endogenous endophthalmitis should also have blood and urine cultures.
Initial treatment includes broad-spectrum intravitreal antibiotics, most commonly vancomycin and ceftazidime. Patients with endogenous endophthalmitis should receive both intravitreal and IV antimicrobials. Therapy is modified based on culture and sensitivity results.
Vision prognosis is often poor, even with early and appropriate treatment. Patients whose vision at presentation is count-fingers or worse should be considered for vitrectomy and use of intraocular corticosteroids. Corticosteroids are, however, contraindicated in fungal endophthalmitis.