Histologic Effects of the High-Energy Pulsed CO2 Laser on Photoaged Facial Skin

Abstract

To delineate the histologic effects of laser resurfacing at photoaged skin, a protocol was designed to biopsy laser test sites in conjunction with adjacent actinically damaged skin at the time of rhytidectomy. Five patients with photodamaged skin underwent resurfacing of the preauricular region to examine the effect of increasing pulse energy and increasing number of passes on depth of dermal penetration. Histologic examination of these specimens showed that the depth of laser injury was dose-dependent. Increasing pulse energy created a deeper wound, and increasing the number of passes similarly produced a larger band of necrosis. Ten patients with photodamaged skin underwent resurfacing of the preauricular region 15 days to 6 months prior to undergoing a rhytidectomy. A comparison of the laser-resurfaced test spot with the adjacent untreated photodamaged skin demonstrated consistent histologic changes to both epidermis and dermis in all specimens examined. Following laser resurfacing, epidermal atrophy and atypia were eliminated, and all specimens exhibited a regeneration of epithelium that was normal in its morphology. Melanocytic hypertrophy and hyperplasia were corrected following treatment, although density and function of epidermal melanocytes appeared normal. All specimens exhibited a substantial amount of neocollagen formation involving both the superficial and middermis following resurfacing. In association with new collagen development within the dermis, there was noted to be a similar degree of proliferation of elastic fibers, as well as a diminution of glycosaminoglycans, which are typically present in actinically damaged elastotic dermis. To determine the effect of laser resurfacing on-black skin, laser test spots were placed in the postauricular region of three black patients. Biopsy of these test sites showed that the histologic effects of laser resurfacing were similar to those observed in Caucasian patients, with complete repopulation of epidermal melanocytes in specimens biopsied 3 months following resurfacing. The histologic effects of laser resurfacing are microscopically similar to those of phenol peeling in terms of the amelioration of photodamage. The distinction between these two treatment methods lies in their apparent effect on epidermal melanocytes, which appear to function normally following laser resurfacing.

Pilot Ultrastructural Evaluation of Human Preauricular Skin Before and After High-Energy Pulsed Carbon Dioxide Laser Treatment

“…The clinical and histologic effects of these lasers have been studied, and it has been shown that the histologic effects of laser resurfacing are microscopically similar to those of phenol peeling, such that, at 90 days after laser treatment, epidermal atypia and dysplasia are corrected and epidermal polarity is restored, the epidermis being then "indistinguishable from that of younger, normal skin." 51 The presence of a subepidermal repair zone consisting of new subepidermal collagen at 3 months after laser treatment, comparable to that seen after medium-depth chemical peels or dermabrasion, has also been described. 50,51 The ultrastructural changes seen in our small group of patients at 30 and 90 days after laser resurfacing appear to correlate with these histologic findings.…”

“…[38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53] Clinical improvement in facial rhytides and photodamage with the new generation of high-energy pulsed carbon dioxide lasers has been well documented. [39][40][41][42][43][44][45][46][47][48]51,52 The precise control over the extent of tissue vaporization results in minimization of thermal damage to the skin, thereby reducing the potential risks of scarring and hyperpigmentation, while maximizing therapeutic efficacy. 39,[49][50][51][52] The histologic changes seen after pulsed laser resurfacing have recently been detailed.…”

“…39,[49][50][51][52] The histologic changes seen after pulsed laser resurfacing have recently been detailed. 50,51 Extensive epidermal necrosis and coagulative changes in the superficial papillary dermis are seen 24 hours after laser administration. Partial or complete reepithelialization is usually seen by day 3, although evidence of papillary dermal collagen damage is still seen.…”

Carbon Dioxide Laser Resurfacing of Rhytides and Photodamaged Skin

“…The various laser systems di#er in the depth of vaporisation achieved with each pass. However, in general, the depth of tissue removal increases with pulse energy and number of passes [4].…”

“…Actinically damaged skin is characterised by epidermal irregularity and atrophy [4]. Keratinocytes are atypical and vary in shape, size and staining properties.…”