THE USE OF DIGITAL MARKING DEVICE WHEN PERFORMING FEMTOSECOND LASER INTRASTROMAL KERATOPLASTY WITH IMPLANTATION OF INTRASTROMAL SEGMENTS

The aim of the study is to assess the practical significance of the use of the digital marking device «VERION™ Image Guided System» in the technology of intrastromal keratoplasty using a femtosecond laser.

Material and methods. According to the developed method, 35 eyes of 27 patients with a diagnosis of keratoconus of the 2nd degree were operated. The median age was 26 years. Formation of intrastromal tunnels was performed using «Femto LDV Z8» femtosecond laser («Ziemer», Switzerland), the laser was centered in strict accordance with the markings obtained by the digital marking device «VERION™ Image Guided System» («Alcon», USA). During the implantation of the segment, this device was also used for its precise positioning in the tunnel. Setting the projection of the required axis, the surgeon intraoperatively to visualize the label that corresponds to the exact position of the end of the segment in the intrastromal tunnel, and carried out precise positioning of the intrastromal segments. R

esults. When performing operations using the indicated method, it was revealed that the patient’s eye at the aplanation stage of a femtosecond laser has a tendency to rotate and decentralize. Minor decentralizations relative to the pupil center were corrected by the displacement of the intrastromal tunnel pattern in the laser working program along the x-axis by 0.1 ± 0.05 mm, along the y-axis by 0.1 ± 0.04 mm. In patients in the postoperative period there was an increase in uncorrected and corrected visual acuity. By 3 months after the operation, functional parameters and keratometric data stabilized: visual acuity without correction and with maximum correction increased to 0.5 ± 0.16 and 0.7 ± 0.12, respectively, keratometry of flat and steep axis declined to 44.3 ± 1.4 and 50,8 ± 3,2 diopters, respectively.

Conclusions. It was found that the applanation of the femtosecond laser aperture on the surface of the conical cornea leads to the rotation of the eye by an average of 9°. The use of femtosecond laser for forming the intrastromal tunnels in the conduct intrastromal keratoplasty requires mandatory marking of the cornea meridian the corresponding to the axis of the cutout for laser centration. Methodology of Verion-assisted femtosecond laser intrastromal keratoplasty allows to position the segments with high precision in accordance with a preoperative calculation that provides high clinical and functional results.

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