New York—Intravitreal steroid injections are gaining credence for their utility in a variety of eye diseases, but they also carry risks that have not yet been fully investigated, said Richard F. Spaide, MD.
"There is a trade-off with intravitreal triamcinolone. It does cause increased IOP, there is a risk of endophthalmitis, and certainly it would be expected to increase the rate of cataract formation," Dr. Spaide said. "However, many of the diseases that we are trying to treat destroy the macula or hurt the macula in an irreversible manner."
At this point, the best approach is to discuss with patients whether it is better to trade the risks that are treatable, such as increased IOP or cataracts, for a treatment that will prevent macular destruction, said Dr. Spaide, who is in private practice with Vitreous-Retina-Macula Consultants of New York.
"By using targeted delivery, we can get high doses without having systemic effects, and we are certain about where the drug is going because we can deliver it there with a needle. Finally, we can get high concentrations of drug into the eye," Dr. Spaide explained.
Triamcinolone acetonide (Kenalog, Bristol Myers Squibb) is the most commonly prescribed drug for intravitreal injections and is used for a number of conditions, including cystoid macular edema, veno-occlusive diseases, proliferative retinopathies, and choroidal neovascularization (CNV).
"It has taken off like wildfire," Dr. Spaide said. The largest series reported has been for CNV.
Watch for complications Injection is easy enough to perform in the clinician's office, Dr. Spaide said, but he emphasized that clinicians should watch carefully for complications both early and late in the procedure and should continue monitoring patients through follow-up visits. They should also be alert for signs of recurrence of the condition for which the patient is being treated. If the disease recurs, it is often possible to reinject.
The use of preinjection topical antibiotics is a matter of clinician preference, Dr. Spaide said, adding that there is no evidence suggesting that they decrease the rate of endophthalmitis.
In either case, the next step is to administer topical anesthetic. Some physicians depend on topical application alone, administering a few drops every minute or so. Patients are often able to tolerate the intravitreal injection without further anesthesia. Some doctors give a subconjunctival injection of lidocaine for patient comfort before the injection. Povidone-iodine is used to prep the eyelids and is administered into the eye itself. This is a very important step, he noted. In Dr. Spaide's practice, the preparation involves a single-dose bottle of povidone-iodine. The triamcinolone is drawn up from a new bottle of 1 ml of 40 mg/ml triamcinolone.
The intravitreal corticosteroid injection is administered with a 30-gauge needle attached to a 1-ml syringe with a Luer-Lok. The use of a Luer-Lok prevents the needle from popping off the end of the syringe. If no Luer-Lok-type syringe is available, a 27-gauge needle should be used.
"Once in a while, the drug may get stuck in the 30-gauge needle and you cannot give the injection. That never happens with a 27-gauge needle. But the disadvantage of a 27-gauge needle is that it is often a little bit painful for the patient," Dr. Spaide said. "If the 30-gauge needle does become occluded, gently pull back on the plunger, and this almost always allows the injection to be completed."
Most patients experience a rise in IOP following the injection. However, the increase is typically moderate and rarely requires paracentesis.
"If one just waits for a while, the pressure will come back down," Dr. Spaide said.