by Dan Roberts
Some people have been reporting considerable pain and/or conjunctival hemorrhaging (eye redness) following intraocular injections of anti-angiogenic drugs (Macugen, Lucentis and off-label Avastin) for wet AMD. Most patients, however, are reporting nothing more than some discomfort. It is important that everyone understands the potential adverse effects of intravitreal injections.
First, it makes no difference what drug is being used. It is the procedure, not the drug, that is the cause of both conditions. Trials for Macugen showed that 10-40% of subjects were affected by eye pain and conjunctival hemorrhaging. Trials for Lucentis showed that eye pain occurred in 17-37% of cases and conjunctival hemorrhaging occurred in 43-77% of treated subjects. Those percentages were comparable in the Lucentis control group that received sham injections.
In preparation for the injection, an anesthetic (to desensitize) and a broad spectrum microbicide (to sterilize) are applied at the injection site. A sterile eyelid speculum (or similar instrument) is used to hold the eyelid open. The injection is administered into the back and side of the eyeball by a syringe with a 27 gauge (Macugen) or 30 gauge (Lucentis) needle. Patients sometimes report a sting when the needle enters, but most report only a feeling of pressure. The injection can leave a small bump that irritates the eyelid for a couple of days. The needle will likely pierce one of the many small blood vessels in the outer covering of the eye. The resulting redness is not painful, nor is it harmful, and it should clear in a day or so.
The pain that is of most concern occurs after the injection. It is a burning sensation that can persist for up to a day afterward, and it is usually accompanied by watering of the eye and foggy vision. One of three conditions may be the cause:
1. Allergic reaction to the microbicide solution
2. Corneal abrasion
3. Dry spots on the cornea
If you experience such pain, it would be wise to see an allergist and/or corneal specialist to determine the cause. It is possible that something can be done to alleviate your symptoms, which is much preferred to foregoing treatment and risking further loss of sight from uncontrolled neovascularization.
Soon, researchers will have developed better methods of delivering drugs to the retina. Promising methods include topical eye drops, slow release compounds and
encapsulated cell technology. Until then, intravitreal injection is the safest and most effective procedure, in spite of complications that can arise. Hopefully, administering physicians will continue to search for solutions to such complications for the maximum well-being of their patients.