Abstract
Keratoconus is a disorder of the cornea characterized by progressive thinning and ectasia which results in deterioration of the quality of vision. Many of the current methods have no effect on the progression of keratoconus and the majority of the patients require surgical intervention. Corneal collagen crosslinking (CCL) with the use of Ultraviolet A radiation (370 nm) and the photosensitizer 0.1% riboflavin phosphate was offered as non-surgical technique of treatment of the cornea. 10 chinchilla rabbit corneas were used for the investigation / 10 corneas served as controls, three experimental groups were formed. 1st group — 6 eyes were treated in vivo using a UVA double diode with 3 mW/cm2 at 370 nm and applying 0.1% riboflavin-5-phosphate for 30 min, 2nd group (2 corneas) — 4.5 mW/cm2 370 nm, 20 minutes, third group (2 corneas) — 3 mW/cm2, 370nm, 60 minutes. 7 days postoperatively keratometry detected a tendency to the increase of curvature radius ® of the treated corneas compared to the controls, with the most effect for the 1st group (averages: 1st group- ® before CCL 7.36±0.27 mm, after CCL 7.64±0.22 mm, controls: 7.33±0.33mm versus 7.35±0.28 mm). Biomechanical stress—strain measurements of treated corneal strips were performed using a microcomputer-controlled testing device and showed the increase of the ultimate stress and decrease of the ultimate strain with the comparison to the control stripes (averages: 1st group stress 6.9±0.9 MPa versus 5.8±0.40 MPa in the controls, strain 36.6±5.42% versus 40.0±5.87%). The method of corneal collagen cross-linking caused the changes in both refractive and biomechanical properties, an increased corneal rigidity and stiffness of the experimental eyes. However, further research is needed for the optimization of the technique, reducing irradiation dose, avoiding possible side-effects.