Non-ablative cutaneous remodeling with a 1.45 microm mid-infrared diode laser: phase II

Abstract

Background: Presented here is phase II of a three-part study of non-ablative cutaneous remodeling with a 1.45 microm diode laser configured with cryogen spray cooling. In phase I, safe heating and cooling parameters were established by examining gross and microscopic changes induced by the laser. Phase II examines clinical changes and side effects in the treatment of single facial rhytids.

Methods: Two men and seven women with Fitzpatrick skin phototypes I-III were treated. Single facial rhytids were treated on three separate occasions 3 weeks apart (six periorbital and three perioral). Single, control wrinkles on the contralateral sides were treated with cryogen spray cooling alone. Subjects were treated with single passes with a 5mm spot for the first two treatments. Owing to a modification in the handpiece design, a 4mm spot was used for the third and final treatment. The average power was 12 W. At each treatment visit, heating times ranged from 200 ms to 300 ms, applied as a series of heating/cooling cycles. One treatment 'cycle' lasted for 100 ms and consisted of continuous laser heating interspersed with programmable parallel cryogen spray cooling bursts.

Results: Patients were assessed 1 day, 1 week, 4 months, and 6 months after treatment. Treatments were well tolerated, and no patient required pain control pre or post operatively. Mild erythema and edema were noted immediately after treatment and typically cleared within 2-3 days. Superficial, branny hyperpigmentation occurred in six patients at both treatment and control sides. This discoloration resolved within 1 week of treatment and left no residual pigment alterations. No whitening or residual scarring occurred. Rhytid scores improved from a baseline score of 2.3 to 1.8 at 6 months after treatment (p>0.05). Patient acceptance of the treatment was high, but most felt that there was little improvement of the treated rhytids.

Conclusion: Although the 1.45 microm diode laser is capable of targeting dermal collagen and stimulating fibrosis at depths where solar elastosis resides, clinical improvement of rhytids was mild and did not correlate well with the degree of histologic changes noted in phase I.