LONG-TERM RESULTS OF DIFFERENT UV-CROSSLINKING TECHNIQUES IN PATIENTS WITH PROGRESSIVE KERATOCONUS

Purpose. To compare a clinical effectiveness of different UV-crosslinking techniques in patients with progressive keratoconus.Material and methods. Randomized prospective clinical trial included 130 eyes of 117 keratoconic patients. There were created 2 equal groups of 65 eyes. In the group I patients underwent a classical UV-crosslinking technique with a complete central corneal deepithelialization, in the group II a UV-crosslinking with dosed corneal epithelium scarification was performed using a new device. The postoperative follow-up period was 24 months. Preoperatively in the group I the uncorrected visual acuity (UCVA) was 0.21±0.11, the best corrected visual acuity (BCVA) was 0.49±0.14, the central corneal pachymetry (CCP) – 469.1±23/4μm, the mean keratometry (Kave) – 46.1±1.7D, in the group II: UCVA was 0.22±0.09, BCVA – 0.48±0.12, CCP – 475.2±28.5μm, Кave – 46.7±1.4D.Results. The mean postoperative pain score was 6.9±1.3, relief on the 3-rd ±1.2 day post-op. in the group I, and 2.8±1.1 relief on the 1-st±0.4 day post-op. in the group II. All patients had a 0.1 to 0.12 visual acuity loss 7 days after the surgery that was due to a mild corneal opacification. At 3 months after operation in both groups the UCVA and the BCVA were back to their preoperative values. In the group I the UCVA increased by 0.07±0.03 (р<0.05) 2 years after the treatment, the BCVA increased by 0.11±0.04 (р<0.05). At that time in the group II the similar values were obtained: 0.08±0.02 (р<0.05), 0.1±0.04 (р<0.05) respectively. The Kave index in both groups gradually decreased during first 12 months after operation and then stabilized. At the end of the follow up it was lower by 2.6±0.5D (р<0.05) in the group I and by 2.4±0.3D (р<0.05) in the group II. According to the anterior OCT, the depth of demarcation line was 327±11μm in the group I and 318±13μm in the group II. The demarcation line was absent in all cases 12 months after surgery. In the early postoperative period 3 months after operation the CCP gradually decreased. It reduced by 3.77±0.83% (р<0.05) in the group I and by 3.17±0.88% (р<0.05) in the group II. After that the CCP slowly increased during the entire follow-up, but 24 months later it was still lower by 2.36±0.57% (р<0.05) in the group I and by 1.68%±0.75 (р<0.05) in the group II. Confocal microscopy 1 month after surgery revealed typical changes of corneal structure at the depth up to 310±9μm (290 to 335) in the group I and 300±8μm (280 to 330) in the group II. A full reinnervation and the repopulation of the cornea with keratocytes was seen 6 months after operation. The only complication (delayed corneal epithelization) was in the group with classical UV-crosslinking technique.Conclusions. The trial revealed similar clinical outcomes after classical UV-crosslinking technique and UV-crosslinking with dosed corneal epithelium scarification, however in the latter case during the postoperative period the severity and duration of pain were significantly reduced