Authors
Bojko E.V.1, 2, Suetov A.A. 1, 3, Doktorova T.A.1, 2, Izmajlov A.S.1, Ivanov A.A.4, Pishchelin A.V.4
1 St. Petersburg Branch S. Fyodorov Eye Microsurgery Federal State Institution St. Petersburg
2 Department of Ophthalmology North-Western State Medical University named after I.I. Mechnikov St. Petersburg
3 State Scientific Research Test Institute of Military Medicine, St. Petersburg
4 Alkom Medica LLC, St. Petersburg
Abstract
Background. Laser photocoagulation is an important treatment method for the various retinal diseases. The development of laser systems with automatic control of the resulting coagulates will improve the effectiveness of laser treatment.
Aim. To study in vitro the possibility of conducting controlled laser photocoagulation using an automated laser system based on the feedback principle.
Materials and methods. A prototype of an automated system for laser photocoagulation of the retina, consisting of a 0.81 µm diode laser and a video capture module integrated into the optical system of the slit lamp, as well as software that controls laser exposure using the feedback principle. For in vitro testing, an original fundus model was used. With a spot diameter of 200 μm and power of 100, 140, 180, 200 and 300 mW, the formation time and uniformity of the resulting coagulates in brightness, the correspondence of the planned and actual brightness of the coagulate were studied.
Results. In an in vitro fundus model, the time of coagulate formation was less than 0.4 s at a power of 180-300 mW, and at a power of 100 mW and a given brightness of more than 50% it reached 1 s or more. At all power levels tested and across the range of brightness levels tested from 15-70% of background, laser burns of uniform brightness (less than 8% coefficient of variation) were obtained. The excess of the actual brightness over the planned one was found in the range of 5-15% of the background level when using a power of 200 and 300 mW, the greatest correspondence between the actual and planned brightness was noted for power values of 140 and 180 mW, and the time of coagulate formation did not exceed 0.6 s at burning brightness 70% background.
Conclusion. Under in vitro conditions, a new automated laser system based on the feedback principle makes it possible to automatically obtain homogeneous, reproducible laser coagulates, while the greatest degree of compliance with the actual and planned brightness of coagulates is achieved using a laser output power is in the range of 140-180 mW.
Keywords: retina, laser photocoagulation, automated laser system, feedback system.
References
1. Boiko E.V. Lazery v oftal’mohirurgii: teoreticheskie i prakticheskie osnovy. SPb: VMedA im.S.M.Kirova; 2003. (In Russ.)
2. Fyodorov SN. Lazernye metody lecheniya zabolevanij glaz. Moskva: Medicina; 1990. (In Russ.)
3. Ardamakova AV, Bol’shunov AV, Ilyina TS, Fedoruk NA, Siplivyĭ VI. Transpupillary laser photocoagulation of ocular fundus: history, the present, and the future. Vestnik Oftalmologii. 2017;133(1):81‑87 [URL] (In Russ.).
4. L´Esperance FA. Ophthalmic Lasers. Photocoagulation, Photoradiation and Surgery. St. Louis: Mosby; 1989.
5. Inderfurth JHC, Ferguson RD, Frish MB, Birngruber R. Dynamic reflectometer for control of laser photocoagulation on the retina. Lasers Surg Med 1994;15:54–61 [URL].
6. Jerath MR, Chundru R, Barrett SF, Rylander HG, Welch AJ. Reflectance Feedback Control of Photocoagulation in Vivo. Arch Ophthalmol 1993;111:531–4 [URL].
7. Schlott K, Koinzer S, Ptaszynski L, Bever M, Baade A, Roider J, et al. Automatic temperature controlled retinal photocoagulation. J Biomed Opt 2012;17:061223 [URL].
8. Serebryakov VA, Boĭko ÉV, Yan AV. Real-time optoacoustic monitoring of the temperature of the retina during laser therapy. J. Opt. Technol. 2014;81(6):14-16 [URL] (In Russ.).
