Title: Topical anesthesia for laser hair removal: comparison of spot sizes and 755 nm versus 800 nm wavelengths.
Authors: Eremia S, Newman N
Journal: Dermatol Surg 2000 Jul;26(7):667-9
Affiliated institution: Cosmetic Surgery Unit, Division of Dermatology, UCLA, Los Angeles, California 90024-6957, USA
BACKGROUND: The Candela alexandrite and the Coherent diode laser systems come equipped with built-in skin cooling systems that are designed to both protect the epidermis, allowing higher fluences, and to alleviate discomfort. Nevertheless, pain can be a significant problem especially with treatment of larger areas. Scatter of the laser beam is reportedly affected by the spot size. It is claimed that larger spot sizes are more effective at identical fluences. OBJECTIVE: This study evaluated the effectiveness of a topical 5% lidocaine cream (ELA-Max) to control pain and compared pain levels at identical fluences between the 8 mm and 12 mm spot size of the alexandrite laser and between the alexandrite and diode laser with its 9 mm spot size. METHODS: The study was conducted in the axillae of 12 patients. Each axilla was divided in half for side-by-side comparison. Half of the right axilla was treated with the alexandrite 8 mm and the other half with the 12 mm spot size at identical fluences. The left axilla was treated at the maximum tolerated fluences with the alexandrite 12 mm spot size and the diode 9 mm spot size. RESULTS: At identical fluences and other parameters, there was significantly more pain with the alexandrite 12 mm spot size than with the alexandrite 8 mm spot size, both with or without topical anesthesia. The alexandrite laser was significantly less painful than the diode laser both with and without topical anesthetic. The difference was most noticeable between the alexandrite 8 mm spot size and the diode 9 mm spot size. Topical 5% lidocaine anesthesia was effective in reducing pain, though not completely, for both the alexandrite and the diode lasers. CONCLUSION: Topical 5% lidocaine cream is a simple and effective method for reducing patient discomfort during laser hair removal procedures, even when a skin cooling device is being used. A larger spot size causes more pain than a smaller spot size at identical fluences. The 800 nm diode laser causes greater discomfort than the 755 nm alexandrite laser.