Minimally invasive non-thermal laser technology using laser-induced optical breakdown for skin rejuvenation

Abstract

We describe a novel, minimally invasive laser technology for skin rejuvenation by creating isolated microscopic lesions within tissue below the epidermis using laser induced optical breakdown. Using an in-house built prototype device, tightly focused near-infrared laser pulses are used to create optical breakdown in the dermis while leaving the epidermis intact, resulting in lesions due to cavitation and plasma explosion. This stimulates a healing response and consequently skin remodelling, resulting in skin rejuvenation effects. Analysis of ex-vivo and in-vivo treated human skin samples successfully demonstrated the safety and effectiveness of the microscopic lesion creation inside the dermis. Treatments led to mild side effects that can be controlled by small optimizations of the optical skin contact and treatment depth within the skin. The histological results from a limited panel test performed on five test volunteers show evidence of microscopic lesion creation and new collagen formation at the sites of the optical breakdown. This potentially introduces a safe, breakthrough treatment procedure for skin rejuvenation without damaging the epidermis with no or little social down-time and with efficacy comparable to conventional fractional ablative techniques.

Figure 1

Ex-vivo skin specimen treated with the new prototype device, stained with haematoxylin and eosin (H&E) demonstrating the creation of lesions inside dermis of human skin.

Figure 2

Specimen from Subject 5, 30 minutes after treatment stained with H&E. Lesions are characterized by cavity, partially collapsed cavity, or collapsed cavity. Insets depict the features of partially collapsed cavity (a); cavity (b) and collapsed cavity (c), where large amount of erythrocytes accumulated in the damaged zones are clearly visualized.

Figure 3

Specimen from subject 1, 30 minutes after the irradiation, stained with Masson Trichrome. Damage is identified by a lesion accompanied with large amount of erythrocytes (circled zone). Damage occurs around 200 mm below skin surface while the epidermis and stratum corneum remain unaffected.

Figure 4

Skin specimen taken at 30 days after treatment was stained with Herovici staining. The mature collagen (collagen I) stained in red whereas the young collagen (collagen III) stained in blue.