Endophthalmitis Management

Empiric Intravitreal Antibiotic Therapy

Once a vitreous sample has been obtained, empiric intravitreal antibiotics are the first-line treatment for suspected bacterial endophthalmitis. They are given immediately, not held pending culture results; delay measurably worsens visual outcomes. The standard combination is vancomycin and ceftazidime. Vancomycin covers gram-positive organisms, including MRSA; ceftazidime covers gram-negative organisms, including Pseudomonas. Together the two agents cover most of the likely pathogens while culture and sensitivity results are pending, and therapy is narrowed once those results return.

The Endophthalmitis Vitrectomy Study

The Endophthalmitis Vitrectomy Study (EVS), published in 1995, is the landmark multicenter trial that put postoperative bacterial endophthalmitis treatment on an evidence base. It defined the roles of vitreous tap-and-inject versus immediate pars plana vitrectomy according to the patient's presenting visual acuity.

The key finding: patients presenting with light-perception-only vision had significantly better outcomes with immediate pars plana vitrectomy. Patients presenting with hand-motions vision or better did equally well with vitreous tap/biopsy plus intravitreal antibiotics alone, without the added risk of an immediate full vitrectomy. A patient who can still count fingers does not need to go straight to the operating room; one who can only perceive light does.

A separate randomization arm tested systemic antibiotics. Adding intravenous ceftazidime and amikacin to the intravitreal regimen made no measurable difference in final visual acuity or media clarity, so systemic antibiotics are not routinely required for exogenous postoperative endophthalmitis. These conclusions come from acute bacterial endophthalmitis after cataract surgery, the specific population the EVS enrolled. Post-traumatic and endogenous endophthalmitis involve different causative organisms and a worse baseline prognosis, so the same vision-based algorithm should not be assumed to transfer to those settings.

Role & Technique of Vitrectomy

The surgical purpose of pars plana vitrectomy in endophthalmitis is removal of infectious and inflammatory vitreous debris. Debulking the bacterial or fungal load and the inflammatory mediators suspended in the vitreous cavity improves clearance of the infection and allows better penetration and distribution of the intravitreal antibiotics that follow.

Vitrectomy technique in an infected eye is modified from a standard vitrectomy for other indications. Surgeons use lower infusion pressure and a limited, core-only vitrectomy rather than higher infusion pressure with complete cortical shaving. In an infected, friable eye, this reduces the risk of choroidal effusion and limits traction on retina that is already inflamed and weakened, while still obtaining adequate culture material and reducing the infectious and inflammatory load.

Fungal & Endogenous Candida Endophthalmitis

For suspected fungal endophthalmitis, intravitreal amphotericin B is the antifungal of choice, selected for its broad-spectrum fungicidal activity against both yeasts and molds. Voriconazole is a common alternative, effective against filamentous fungi and with the added advantage of oral bioavailability. Both agents are also used for endogenous candida endophthalmitis, with voriconazole increasingly favored for its better vitreous penetration.

In severe fungal endophthalmitis unresponsive to systemic and intravitreal therapy alone, surgeons may combine vitrectomy with intraoperative injection of amphotericin B or voriconazole directly into the vitreous cavity. This achieves a higher local drug concentration at the infection site when systemic penetration alone is inadequate.

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