Fractional Erbium laser in the treatment of photoaging: randomized comparative, clinical and histopathological study of ablative (2940nm) vs. non-ablative (1540nm) methods after 3 months

Abstract

Background: Fractional non-ablative lasers keep the epidermis intact, while fractional ablative lasers remove it, making them theoretically more effective.

Objectives: To evaluate the clinical and histological alterations induced by fractional photothermolysis for treating photoaging, comparing the possible equivalence of multiple sessions of 1540nm Erbium, to one session of 2940nm Erbium.

Methods: Eighteen patients (mean age 55.9) completed the treatment with three sessions of 1540nm fractional Erbium laser on one side of the face (50 mJ/mB, 15ms, 2 passes), and one session of 2940nm on the other side (5mJ/mB, 0.25ms, 2 passes). Biopsies were performed before and 3 months after treatment. Clinical, histological and morphometric evaluations were carried out.

Results: All patients presented clinical improvement with no statistically significant difference (p> 0.05) between the treated sides. Histopathology revealed a new organization of collagen and elastic fibers, accompanied by edema, which was more evident with the 2940nm laser. This finding was confirmed by morphometry, which showed a decrease in collagen density for both treatments, with a statistical significance for the 2940nm laser (p > 0.001).

Conclusions: Three 1540nm sessions were clinically equivalent to one 2940nm session. The edema probably contributed to the positive results after three months, togheter with the new collagen and elastic fibers organization. The greater edema after the 2940nm session indicates that dermal remodeling takes longer than with 1540nm. It is possible that this histological superiority relates to a more prolonged effect, but a cohort longer than three months is needed to confirm that supposition.

FIGURE 1

Before (A) and after (B) treatment. Patient (1) treated with one 2940nm session on the right side of the face and three 1540nm sessions on the left side of the face. There was considerable improvement in the color criterion for both tretaments Patient (2) treated with three 1540nm sessions on the right side of the face and one 2940nm sessions on the left side, with considerable improvement in the wrinkles criterion for both treatments. No differences between sides were observed in any of the cases

FIGURA 2

The table illustrates erytema, edema, and desquamation, which were more intense on the side treated with the 2940nm laser

FIGURA 3

Epidermis stained with H.E., (A) before 10x and 40x; (B) after three months of the 1540nm treatment, 10x and 40x. The cones were considered shorter, the Malpighian layer was considered rectified. These changes were seen after 2940nm treatment

FIGURE 4

New arrangement of collagen fibers seen during the H.E. (top line) and picrosirius staining (botton line). Pre-tretament fibers were hyalinized, thick and distributed irregularly in the Grenz zone (A). After three months, fibers were thinner and appeared regularly (B) or fragmented (C), in the same location. The same patterns were observed after 1540nm and 2940nm treatments

FIGURE 5

Edema in the papillary dermis after treatment seen in plates stained with picrosirius 40x; (A) before and (B) after; 1540nm laser (top line), and 2940nm laser (bottom line). The edema was considered greater after 2940nm treatment

FIGURE 6

New arrangement of elastic fibers. Considerable changes in the elastic fibers before tretament, represented by the absence of fibers in the dermo-epidermical junction and diminushed density of the fibers in the papillary and high reticular dermis (A). Superficial reconstruction of the oxitalanic and elauninic fibers, and papillary and high reticular dermis with more dense fibers were seen after three months of treatment (B); orcein 10x and 40x. The same patterns were observed for both tretments.

GRAPH 1

Morphometry. Morphometric studies. Graph showing lower density collagen after three months for both treatments, but the difference analyzed through the t-student test was only considered statistically significant for 2940nm treatment (p<0.001)

GRAPH 2

showing increase in density of elastic fibers after three months for both treatments but there was statistical significance only for the 1540nm treatment (p<0.001)