Meticulous intravitreal injection technique essential for minimizing endophthalmitis risk

Knowledge of appropriate technique for intravitreal injection is becoming increasingly important as the indications and agents available for intravitreal therapy expand, said Rajendra S. Apte, MD, at the World Ophthalmology Congress.

"Endophthalmitis is a significant risk associated with these procedures that may be performed in an office-based setting. However, there is good evidence from the VISION study with pegaptanib sodium (Macugen, OSI/Eyetech Pharmaceuticals) that the risk is modifiable through careful attention to the injection protocol," said Dr. Apte, assistant professor of ophthalmology and visual sciences, Washington University School of Medicine, St. Louis, MO.

Proper technique can be summarized by recommendations to keep it sterile and make it simple. Although product sterility is not a concern for the anti-VEGF agents that come prepackaged, when administering triamcinolone acetonide (Kenalog, Bristol-Myers Squibb), consideration should be given to using a new bottle for every treatment. For anesthesia, surgeons may choose to administer a subconjunctival lidocaine injection or to apply a sterile cotton-tipped applicator soaked with a topical anesthetic or lidocaine jelly over the intended injection site. Dr. Apte noted that use of lidocaine jelly is controversial due to the potential for microbial flora to be trapped in the agent, but it is his technique of choice.

The role of preoperative and postoperative broad-spectrum antibiotics is also contentious because there is no evidence proving such treatment reduces endophthalmitis risk. However, povidone-iodine is still considered the gold standard for preparation. A 5% solution should be used to rinse the ocular surface and cul-de-sac generously while the lids should be scrubbed with a cotton-tipped applicator soaked in 10% povidone-iodine. After placing a sterile eyelid speculum, application of 5% povidone-iodine directly over the injection site might also be considered, allowing for drying prior to medication delivery.

The pars plana injection should be delivered 3 to 4 mm posterior to the limbus. In order to avoid vitreous wick syndrome, surgeons might shift the conjunctiva with a cotton-tipped applicator prior to injection and then roll a cotton-tipped applicator over the entry site to minimize reflux as the needle is withdrawn.

The fundus should be checked with indirect ophthalmoscopy following the injection, but there is no need to check IOP immediately after surgery. After intravitreal triamcinolone, patients should receive ongoing monitoring for IOP elevations.