Impact of a mid-infrared laser on eye tissues

Purpose. To study the effect of mid-infrared laser radiation on eye tissues. Material and methods. As a laser, an experimental laser device “Laser scalpel in the middle infrared range 2-8µm for precision surgery” developed at the Vavilov State Optical Institute. The experiment was carried out at a laser radiation wavelength of 3µm, which coincides with the peak of the spectral absorption of water. The retina, choroid, and sclera of pig eyes were used as biological tissue. The effect of laser radiation on tissue was carried out in air. The impact of laser radiation on eye tissues was assessed using an EVO LS10 scanning electron microscope from Zeiss (Germany). After obtaining an image on an electron microscope using the GNU Image Manipulation Program, the depth and diameter of the crater and the width of the collateral damage were calculated. Results and discussion. When exposed to a single laser pulse with an energy of 1 MJ, a through retinal defect was observed. With continuous exposure to laser radiation on the choroid with an energy from 1 to 3 MJ, the crater depth was 128–150 microns, the crater width was 87–110 microns, the collateral damage zone was 50–71 microns. With continuous exposure to laser radiation with similar parameters on the sclera, the depth of the crater, the width of the crater and the area of collateral damage were larger. Conclusions. The depth, width of the crater, the zone of collateral damage when exposed to laser radiation are directly proportional to the time, frequency and energy of the radiation. This laser can be useful in ophthalmic surgery, in particular in vitreoretinal surgery. However, further studies are needed to optimize the parameters of laser radiation. Keywords: vitrectomy, laser vitrectomy, photovitrectomy, Er:YAG laser, mid-infrared spectrum, laser ablation, precision surgery.