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T. Bende, B. Jean, V. Pustovalov, A. Smetannikov; INVESTIGATIONS OF THE OPTICAL AND THERMAL PROCESSES OF LASER THERMAL KERATOPLASTY – NEW OPTIONS . Invest. Ophthalmol. Vis. Sci. 2004;45(13):183.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:The investigations of the optical and thermal processes of laser thermal keratoplasty (LTK) and the variation and optimisation of the parameters of heated region in cornea during LTK. Methods:Computer modeling is used to investigate cw laser coagulation inside the cornea with all its tissue layers. An optimal coagulation temperature of 65 to 85 °C for a permanent steeping effect and minimal heating of endothelium and aqueous humour are used. Results:The results of computer modelling demonstrate the possibility not only to determine the amount of heated tissue but also the intrastromal isotherms and thus the shape of the heated tissue volume. This can be achieved by the selection of appropriate laser wavelengths in the spectral range between 1.35 – 1.42 µm and 1.5 – 1.85 µm (absorption coefficient of corneal tissue in the range 5 – 20 cm–1) and an adapted application time. Focusing of the laser beam by means of a focusing handpiece has to be adapted as well (focal length between 400 – 600 µm with a beam diameter waist of about 80 – 200 µm inside the cornea). Conclusions:The computer modeling offers new option for future LTK using tunable or multi wavelength laser in combination with focusing handpieces. The variation of laser wavelength (absorption coefficient of corneal tissue) for constant laser beam parameters leads to significant changes in shape, position, dimensions, and amount of temperature of the heated region inside corneal stroma.
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