Endophthalmitis prophylaxis crucial after intravitreal injection, surgeon says

NAPLES, Italy — Because of the increasing number of intravitreal injections administered as therapy for various posterior segment diseases, physicians could be facing an emerging epidemic of endophthalmitis if the necessary precautions are not taken, according to one surgeon.

Intravitreal medications often require repeated administration, sometimes as often as once a month. "Patients receive six to 12 injections per year, and potentially, each one of them poses a threat for infection," Terrence P. O'Brien, MD, said here at the joint meeting of Ocular Surgery News and the Italian Society of Ophthalmology.

Although the mechanisms of infection are not completely understood, various organisms are normally present on the conjunctival surface, and passing the needle through the conjunctiva and sclera via the pars plana approach may present an opportunity for these organisms to gain entry into the eye. Also, the transient decrease in pressure that is caused by the needle entering the eye may pull the organisms from the tear film and ocular surface inward through the sclerotomy made by the needle, he said.

"Typically, the size of the needle is 27-gauge or 30-gauge, but this is still large enough to create a portal for the entry of organisms," Dr. O'Brien said.

An additional problem is that intravitreal injections are often administered in an office setting rather than in a surgical theater, where the level of antisepsis is higher and protocols to prevent infections are better defined and stricter.

"We must make sure that all precautions are taken ... in an office environment to guarantee safe, sterile surgery," he said.

A panel of experts met recently in the United States to try and provide recommendations on this particular treatment modality, but there was no consensus on a universal routine, Dr. O'Brien said.

"There is a lot of controversy about prevention and pre-injection preparation. Gloves were recognized by everyone to be beneficial, and the use of a sterile lid speculum was recommended. However, there was incomplete agreement about the need for draping the eyelid and lashes," he said.

There was consensus on the use of an antiseptic, namely 10% povidone iodine, for the eyelid and lashes and a drop of 5% povidone iodine placed directly onto the ocular surface.

Antibiotics were another controversial topic, he said, and different opinions were expressed concerning the type, timing and frequency of antibiotic administration before and after the treatment.

The majority said a broad spectrum antibacterial agent such as a fluoroquinolone administered in four consecutive topical doses before the injection and four to six times a day for the first 5 to 7 days after the treatment may be sufficient to protect against the most likely organisms.

"Certainly there is no universal protection provided by a single antibiotic agent, and the effects might be limited by incomplete penetration of topical medications into the vitreous cavity, where the organisms are delivered by the injection," Dr. O'Brien said.

He also expressed concern about resistance to antibiotics that is increasingly seen in the clinical practice and proved by laboratory data.

However, statistics show that the high rate of endophthalmitis observed in the first studies on intravitreal injections has decreased since new protocols for safety were introduced.

"This proves that we do need to have a rational approach to prophylaxis to avoid infection," Dr. O'Brien said.