Ocular anesthesia: using lidocaine gel

Considering patient satisfaction with anesthetic gel versus drops

For practitioners preparing for short procedures such as cataract or pterygium surgery, lidocaine gel can be a viable option, according to Frederick (Rick) W. Fraunfelder, M.D., director, Cornea and Refractive Surgery Division, and associate professor of ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland. Study results published in the November 2009 issue of Clinical Ophthalmology show the gel to be safe and effective with a longer duration of action than topical drops.
In the recent trial, which Dr. Fraunfelder called a retrospective review of prospective studies, investigators looked at approximately 25 studies. Of these studies, 15 were prospective, randomized, controlled trials and the remaining investigations were retrospective studies. “Usually those studies would compare lidocaine gel to topical anesthetics that are not gels, like eye drops such as topical tetracaine or topical proparacaine, and then compare the pain between the two,” Dr. Fraunfelder said. “Usually investigators would ask patients, ‘On a scale of 1 to 10 how much do you feel?’ They would also find out how long it took for the gel to work compared to the topical drops.”

Potent pain reliever

Investigators here determined that findings for the gel’s anesthetic properties were promising. “In general it takes about five minutes for the gel to work and more often than not, patients preferred the anesthetic effect of the gel to the topical eye drops,” Dr. Fraunfelder said.
With the gel, patients were less likely to experience pain. “I think the advantage is that it’s potentially a more complete anesthesia,” Dr. Fraunfelder said. While some patients complained of pain with the drops, usually they did not with the gel. “One of the findings was that with the drops the pain was a 2 or 3 out of 10,” Dr. Fraunfelder said. “But more often than not, with the gel patients reported a 0 out of 10 score of pain.” Investigators found the lidocaine gel to be very safe. “The main side effects from the gel are conjunctival injection, hyperemia, and irritation,” Dr. Fraunfelder said. “It can also potentially cause some temporary staining of the cornea.” Breakthrough pain was also considered an adverse event. “We found that the adverse event rate from gel was about 2% to 6% across all of the studies,” Dr. Fraunfelder said.
Efficacy of the gel depended in part upon the strength selected. “The gel comes in different concentrations and the more powerful the gel, the more potent it is,” Dr. Fraunfelder said. “There’s a lidocaine gel that comes in 1.5%, 2.5%, and 3.5% and the stronger the gel, the more powerful the anesthetic.” In addition, the gel tends to stay on the eye for a longer duration than the drops due to its viscosity. “When you put the gel in the eye it sits there for 5 minutes and is not absorbed by the puncta as quickly as the tears,” Dr. Fraunfelder said. “Because of that it’s in contact with the conjunctiva longer and it’s inducing anesthesia better because it’s being absorbed more thoroughly. That‘s probably why it works a bit better than drops, which are cleared more quickly.”
In reviewing the studies in the literature, investigators did find something unexpected. “I was surprised that in some of the controlled trials they would do a sham, where some patients would get a gel put in their eye that had no anesthesia in it. About 22% of people that had a sham gel put on their eye actually reported that they got full anesthesia from that,” Dr. Fraunfelder said. “The power of suggestion is very strong.”

Ideal procedures

Dr. Fraunfelder was not surprised that the gel was found to be more effective than the topical drops as a rule. “It lasts about 10 minutes and takes about five minutes for it to get full anesthesia,” he said. Given this, he thinks that the topical gel is best suited for short ophthalmic procedures; otherwise it’s necessary to reapply. “I think that it’s ideal for cataract surgery and for quick anterior segment external eye disease surgeries such as a superficial keratectomy, pterygium surgery, or removing small lesions from the surface of the eye,” Dr. Fraunfelder said.
Overall, Dr. Fraunfelder sees the lidocaine gel as a good, sometimes overlooked, option for ophthalmic practitioners. “I think that lidocaine gel is safe, effective, and potentially underutilized as a tool for ophthalmic anesthesia,” he said.

Editors’ note: Dr. Fraunfelder has no financial interests related to his comments.

Contact information

Fraunfelder: fraunfer@ohsu.edu