Evaluation of the Impact of Mid-Infrared Laser Radiation on Eye Tissues (Experimental Study)

Purpose — to study the effect of a mid-infrared laser with a wavelength of 3.0 μm on the eye tissue. Materials and methods. An experimental laser device “Laser scalpel in the middle infrared range 2–8 μm for precision surgery” was used. The range of the radiation spectrum generated by this laser coincides with the spectral absorption peaks of such biological tissue chromophores as water, proteins and cholesterol esters, which makes it possible to use this laser in precision surgery (ophthalmology, neurosurgery, vascular surgery). In this study, we chose a wavelength of 3 µm, which coincides with the peak of the spectral absorption of water. The retina, choroid, sclera of porcine and cadaveric eyes was used as biological tissue. The effect of laser radiation on tissue was carried out in air. The application of coagulates was performed in different modes: 1) single pulses, 2) continuous mode. The impact of laser radiation on eye tissues was assessed using a scanning electron microscope. Results. When exposed to a single laser pulse with an energy of even 1 mJ, a through defect of the retina was observed. When exposed to a single laser pulse on the choroid with an energy of 1 to 3 mJ, the depth of the crater was 110–130 µm, the width of the crater was 97–122 µm, and the zone of collateral damage was 22–28 µm. When exposed to a single laser pulse on the sclera with an energy of 1 to 3 mJ, the depth of the crater was 170–201 µm, the width of the crater was 260–303 µm, and the zone of collateral damage was 57–72 µm. With continuous exposure to laser radiation on the choroid and sclera, the depth, width of the coagulate, the zone of collateral damage with similar laser parameters were greater than with a single pulse. Conclusion. Using this laser at a wavelength of 3 μm, it is possible to dissect eye tissues, which can be useful in vitreoretinal surgery for retinotomy, cutting out the choroid-pigment epithelium complex, and in antiglaucoma surgery for non-penetrating deep sclerectomy. However, further research is needed to optimize such laser parameters as the number of pulses in a packet, pulse duration, and pulse energy.

1. Patel CKN. Continuous-Wave Laser Action on Vibrational-Rotational Transitions of CO2. Physical review journals archive. 1964;136(5):1187–1193. doi: 10.1103/PhysRev.136.A1187.

2. Blackwell RE, Jemison DM, Foy BD. The holmium: Yttrium-aluminum-garnet laser in wrist arthroscopy: A five-year experience in the treatment of central triangular fibrocartilage complex tears by partial excision. J. Hand Surg. 2001;26A:77–84. doi: 10.1053/jhsu.2001.20157.

3. Ceccato P, Flasse S, Tarantola, S. Detecting vegetation leaf water content using reflectance in the optical domain. Remote Sens. Environ. 2001;77:22–33. doi: 10.1016/S0034-4257(01)00191-2.

4. Anderson RR, Parrish JA. Selective photothermolysis: Precise microsurgery by selective absorption of pulsed radiation. Science. 1983;220:524–527. doi: 10.1126/science.6836297.

5. Peyman GΑ, Katoh N. Effects of an erbium: YAG laser on ocular structures. Int Ophthalmol. 1987;10(4):245–253. doi: 10.1007/BF00155632.

6. D’Amico DJ, Moulton RS, Theodossiadis PG. Erbium:YAG Laser Photothermal Retinal Ablation in Enucleated Rabbit Eyes. Am J Ophthalmol. 1994;117(6):783–790. doi: 10.1016/s0002-9394(14)70323-x.

7. Hutchens TC, Darafsheh A, Fardad A. Detachable microsphere scalpel tips for potential use in ophthalmic surgery with the erbium:YAG laser. J Biomed Opt. 2014;19(1):18003. doi: 10.1117/1.JBO.19.1.018003.

8. Schastak S, Yafai Y, Yasukawa T. Flexible UV Light Guiding System for Intraocular Laser Microsurgery. Lasers Surg Med. 2007;39(4):353–357. doi: 10.1002/lsm.20480.

9. Borirakchanyavat S, Puliafito CA, Kliman GH. Holmium-YAG Laser Surgery on Experimental Vitreous Membranes. Arch Ophthalmol. 1991;109(11):1605–1609. doi: 10.1001/archopht.1991.01080110143052.

10. Astakhov YS, Belekhova SG, Dal NY. Choroidal thickness in normal subjects and in age-related macular degeneration. Ophthalmology journal. 2014;7(1):4–7 (In Russ.). doi: 10.17816/OV201414-7.

11. Doga AV, Magaramov DA, Solomin VA. Importance of choroidal thickness measurment in patiens with submacular neovascular membrane. Fyodorov Journal of Ophthalmic Surgery. 2014;2:40–43 (In Russ.).

12. Klink T, Schlunck G, Lieb W. CO2, Excimer and Erbium:YAG Laser in Deep Sclerectomy. Ophthalmologica. 2008;222(2):74–80. doi: 10.1159/000112622.