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Corneal collagen fibrile contraction under 2.1 µm holmium laser irradiation

T. DASCALU1,* , C. DASCALU2

Affiliation

  1. Quantum Electronics Laboratory, National Institute for Laser, Plasma and Radiation Physics, CP MG-36, Bucharest Romania
  2. Department of Physics, “Politehnica” University of Bucharest, Splaiul Independentei 313, R-77206, Bucharest, Romania

Abstract

We present a new method to measure the collagen fibrils’ contraction velocity due to collagen coagulation under 2.1 µm wavelength laser irradiation. The experiment was performed in vitro on porcine corneal tissue. The tissue marked with fluorescent collagen antibody was placed under the microscope objective and irradiated at ≈100 W/cm2 power density with 488nm wavelength. This irradiation was made through an optical setup that produces light and dark fringes on tissues surface resulting a stable photobleaching pattern with ≈63 µm interfringe distance. The tissue contraction follows the laser pulse irradiation at 2.1 µm wavelength. The shrinkage of the corneal tissue, without epithelial destruction, is obtained by irradiation with laser pulses that ranges from 15 mJ to 100 mJ. A photomultiplier attached to the fluorescence microscope detects the changes of the bleached pattern position and the resulted signal is analyzed allowing the calculation of the contraction’s speed of irradiated collagen fibrils. Contraction’s velocity of 0.57 mm/sec for 50 mJ pulse irradiation was measured..

Keywords

Laser thermokeratoplasty, Cr:Tm:Ho:YAG laser, Fluorescence photobleaching, Argon laser, Collagen shrinkage.

Submitted at: Jan. 17, 2006
Accepted at: July 20, 2006

Citation

T. DASCALU, C. DASCALU, Corneal collagen fibrile contraction under 2.1 µm holmium laser irradiation, Journal of Optoelectronics and Advanced Materials Vol. 8, Iss. 4, pp. 1552-1556 (2006)