Intradermally focused infrared laser pulses: Thermal effects at defined tissue depths
✍ Scribed by Misbah Huzaira Khan; R. Kehl Sink; Dieter Manstein; David Eimerl; R. Rox Anderson
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 346 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0196-8092
No coin nor oath required. For personal study only.
✦ Synopsis
Background and objectives:
To produce controlled, spatially confined thermal effects in dermis.
Study designs/materials and methods:
A 1 w, 1,500 nm fiber-coupled diode laser was focused with a high numerical aperture (na) objective to achieve a tight optical focus within the upper dermis of skin held in contact with a glass window. the delivery optics was moved using a computer-controlled translator to generate an array of individual exposure spots. fresh human facial skin samples were exposed to a range of pulse energies at specific focal depths, and to a range of focal depths at constant pulse energy. cellular damage was evaluated in frozen sections using nitro-blue tetrazolium chloride (nbtc), a lactate dehydrogenase (ldh) activity stain. loss of birefringence due to thermal denaturation of collagen was evaluated using cross-polarized light microscopy. the extent of focal thermal injury was compared with a model for photon migration (monte carlo simulation), heat diffusion, and protein denaturation (arrhenius model).
Results:
Arrays of confined, microscopic intradermal foci of thermal injury were created. at high na, epidermal damage was avoided without active cooling. foci of thermal injury were typically 50-150 microm in diameter, elliptical, and at controllable depths from 0 to 550 microm. both ldh inactivation and extracellular matrix denaturation were achieved.
Conclusion:
Spatially confined foci of thermal effects can be achieved by focusing a low-power infrared laser into skin. size, depth, and density of microscopic, thermal damage foci may be arbitrarily controlled while sparing surrounding tissue. this may offer a new approach for nonablative laser therapy of dermal disorders.