Original article Intraoperative prevention of corneal ring decentration during intrastromal implantation for central keratoconus A.V. Tereshchenko, E.N. Vishnyakova, I.G. Trifanenkova, S.K. Demyanchenko S. Fyodorov Eye Microsurgery Federal State Institution, Kaluga Branch, Kaluga, Russian Federation Medical Institute of Kaluga Tsiolkovski State University, Kaluga, Russian Federation Purpose. To develop a method for intraoperative prevention of decentration of the corneal ring manufactured by NEP Eye Microsurgery LLC during intrastromal implantation for stage 2 central keratoconus. Material and methods. This work included 5 patients (6 eyes) from 32 to 42 year old diagnosed with stage 2 central keratoconus in combination with high myopia, who required implantation of rings manufactured by NEP Eye Microsurgery LLC from 200–250 microns with an internal diameter of 5 mm. The parameters of the intrastromal ring were calculated using the data from nomograms for MyoRing rings and nomograms for calculating intrastromal segments for the spherical component. A femtosecond laser, Femto LDV Z8 (Ziemer, Switzerland) was used to form an intrastromal channel. Capsulorhexis program for centering on the visual axis was used to perform digital marking of the cornea using the Verion system. Results. In 6 months, in all cases there was an increase in visual acuity, a decrease in the spherical and cylindrical components of refraction, a decrease in keratometry data, and the thickness of the cornea remained stable. All patients had a marked decrease in keratometric parameters. Keratotopography results had a specific appearance, corresponding to the central location of the ring. Not a single case of ring displacement or decentration was identified. Conclusion. Developed technique ensures precision implantation of an intrastromal corneal ring with precise centering along the visual axis, reducing risk of decentration of the ring in the postoperative period. Further studies are needed on larger clinical material and over a longer observation period. Key words: primary corneal ectasia, keratoconus, intrastromal keratoplasty, intrastromal corneal ring