Selective Photothermolysis: Precise Microsurgery by Selective Absorption of Pulsed Radiation

Abstract

Suitably brief pulses of selectively absorbed optical radiation can cause selective damage to pigmented structures, cells, and organelles in vivo. Precise aiming is unnecessary in this unique form of radiation injury because inherent optical and thermal properties provide target selectivity. A simple, predictive model is presented. Selective damage to cutaneous microvessels and to melanosomes within melanocytes is shown after 577-nanometer (3 x 10(-7) second) and 351-nanometer (2 x 10(-8) second) pulses, respectively. Hemodynamic, histological, and ultrastructural responses are discussed.

Iris damage and acute pigment dispersion following photo-epilation

“…Corneas of diabetic patients exhibit remarkable abnormalities of nerves, basement membranes, and cellular layers. 1 Confocal microscopy has become a popular technique to observe the structure of cornea in vivo in several disease states afflicting the cornea including diabetes mellitus. 2,3 Among the less common observations in the corneas of diabetic patients are the faint vertical lines at the level of Descemet's membrane and endothelium, initially described by Waite and Beetham 4 and Henkind and Wise.…”

“…It relies on the principle of selective photothermolysis whereby use of an appropriate wavelength and pulse duration of light causes injury that is confined to the desired target tissue while sparing surrounding structures. 1,2 We report a case of iris damage and acute pigment dispersion after the use of long-pulsed infra-red (LPIR) alexandrite laser for photo-epilation of the eyebrow.…”

Mathematical modeling of the optimum pulse structure for safe and effective photo epilation using broadband pulsed light

“…Anderson and Parrish (19) first introduced the principle of selective photothermolysis applicable to the laser treatment of cutaneous lesions in 1983. Selective photothermolysis describes how a target can be selectively destroyed by using the appropriate wavelength, pulse duration, and energy, and that the optimum level of thermal absorption in the target should be achieved with the least interference to the surrounding non‐target tissue (19) .…”

“…Selective photothermolysis describes how a target can be selectively destroyed by using the appropriate wavelength, pulse duration, and energy, and that the optimum level of thermal absorption in the target should be achieved with the least interference to the surrounding non‐target tissue (19) . In tandem with the principle of selective photothermolysis is the concept of thermal relaxation time (20) .…”

“…The thermal relaxation time for hair follicles that are 200–300 μm in diameter is approximately 40 to 100 milliseconds. If pulse duration was the only factor, then the ideal pulse duration should lie between the thermal relaxation time for melanosomes found in the epidermis, which is approximately 3 to 10 milliseconds, and the thermal relaxation time for hair follicles (19) . Applying the theory of selective photothermolysis using a laser for cutaneous disorders is the same when using IPL technology.…”