Efficiency and safety of the Russian-made KERATOLINK device used to treat patients with stage I–II keratoconus and pellucid marginal corneal degeneration

Ultraviolet cross-linking (UVCL) of corneal collagen is one of the leading methods for treating primary progressive keratectasia. Purpose : to evaluate the effectiveness and safety of a new Russian-produced device for UVCL, KERATOLINK, in treating patients with stage I–II keratoconus and pellucid marginal corneal degeneration (PMCD). Material and methods . UVCL was performed in 36 patients (46 eyes) aged 18 to 35 years, including 22 patients (30 eyes) with stage I–II keratoconus and 14 patients (16 eyes) with PMCD. Three programs were used: 1 — standard UVCL with radiation intensity from 2.5 to 3.0 mW/cm2 and 30-minute exposure time (8 patients, 10 eyes); 2 — accelerated UVCL 1: from 8.0 to 9.0 mW/cm2 and exposure time 10 min (20 patients, 25 eyes); 3 — accelerated UVCL 2 with radiation intensity from 16.0 to 18.0 mW/cm2 and 5-minute exposure time (8 patients, 11 eyes). The patients were examined before UVCL, then a week, 1, 3, 6 months after it. The examination included vision acuity, autorefkeratometry, biomicroscopy, Scheimpflug analysis on a Galilei G6 device (Ziemer, Switzerland), optical coherence tomography of the cornea (Anterion, Heidelberg Engineering, Germany), aberrometry (OPD-scan III, Nidek, Japan), confocal biomicroscopy (ConfoScan 4, Nidek, Japan), and determination of biomechanical parameters of the cornea - corneal resistance factor (CRF) and corneal hysteresis (CH) on an ORA device (Reichert Inc., USA). Results . 6 months after UVCL, an increase in visual acuity from 0.56 ± 0.16 to 0.68 ± 0.13 was noted in stage I-II keratoconus, and from 0.66 ± 0.17 to 0.75 ± 0.14 (p < 0.05) in PMCD. Flattening of the cornea at the steepest point increased from 54.46 ± 4.39 to 52.87 ± 4.26 D and from 52.64 ± 2.88 to 51.53 ± 2.84 D, while the rigidity increased in CRF from 6.93 ± 1.00 to 8.38 ± 1.00 mm Hg and from 8.02 ± 0.68 to 9.13 ± 0.97 mm Hg. (p < 0.03), and CH increased from 7.64 ± 0.47 to 8.61 ± 0.73 mm Hg and from 6.89 ± 1.20 to 8.17 ± 0.90 mm Hg (p < 0.05). The analysis of various UVCL programs revealed no difference in the recovery period and showed comparable clinical and functional results. Conclusion . The new KERATOLINK device is shown to be effective and safe in the treatment of stage I–II keratoconus and PMCD. A decrease in ophthalmometry indicators, and an increase in corneal rigidity and visual acuity indicate an improvement in the optical and biomechanical properties of the patients’ cornea and stabilization of the pathological process. The use of local UVCL and accelerated algorithms with a significant reduced exposure time improves the comfort and tolerability of the procedure, and also reduces the risk of complications. The KERATOLINK device provides a personalized approach to the treatment of patients due manual and stationary use options, the availability of standard and accelerated UVCL programs, providing for the choice of power and duration of the procedure, with smooth adjustment and fixation of the size and the area of treatment. The laser focal length control system ensures the maintenance of the required UVCL intensity regardless of the size of the impact spot. It has good prospects for clinical practice.