Investigation of the influence of riboflavin-UV induced crosslinking on the cornea in the experiment

Purpose: Morphological examination of the efficiency of the influence of various doses of riboflavin-UV induced crosslinking on the state of the corneal stroma in experimental animals.
Methods: In the work were used rabbits males breed Chinchilla mass of 1.5-2.0 kg. the experiment was conducted on 20 eyes of 10 animals, which performed the routine crosslinking. Experimental animals, depending on the power UV-laser irradiation, were divided into 4 groups: the animals of the 1 group with the minimum intensity of radiation (30 minutes, 0.27 J), animals 2 group with medium intensity of radiation (15 minutes, 0.34 J)), animals 3 groups with high intensity of radiation (30 minutes, 0.34 J)), the control group 4 (without UV-radiation). Date of dynamic observation of the experimental animals was 5 days, after which the animals were taken out of the experiment. Morphological investigations were carried out by means of light and electron microscopy.
Results: In groups of experimental animals with the impact of riboflavin UV-radiation in the stroma of the cornea were found the appearance of the areas of cross-stitched collagen fibers and fibrils. In the zone of the crosslinking were found activated keratoblasts.
Near the membranes of these cells the contents of the vacuoles are released and filaments finish building of the collagen fibers. the epithelium of the corneas of all experimental animals recovered fully, with no morphological signs of endothelial damage has been found. Electron-microscopic investigation of stroma of corneas of the experimental animals of the control group after the experiment showed the presence of keratocytes in an inactive form and collagen fibers of stroma, packed in the form of plates or beams with a characteristic orientation.
Conclusion: Studies have shown that UV-irradiation of the cornea leads to the appearance of linking between the fibers of collagen and actively synthesizing cells in the stroma of the cornea, which points to a possible stimulation of collagen producing processes. When in excess of the threshold values of the energy of the UV-irradiation we have not identified any morphological signs of damage of the endothelial layer of the cornea.

1. Анисимов С. И., Пожарицкий М. Д., Ларионов Е. В. и др. Первый опыт коррек- ции прогрессирующего гиперметропического сдвига методом роговичного кросс-линкинга у пациентов, перенесших в прошлом радиальную кератото- мию // Офтальмология. — 2010. — Т. 7, No 4. — С. 5-10.

2. Jankov L. Mr. Corneal Collagen Cross-Linking // Middle East Afr. J. Ophthalmol. — 2010. — Vol. 17. — P. 21-27.

3. Kruse FE. Stem cells and corneal epithelial regeneration // Eye. — 1994. — Vol. 8. — P. 170-183.

4. Mazzotta C. Treatment of progressive keratoconus by riboflavin-UVA-induced cross-linking of corneal collagen: ultrastructural analysis by Heidelberg Retinal Tomograph II in vivo confocal microscopy in humans // Cornea. — 2007. — Vol. 26. — P. 390-397.

5. Spoerl E. Stress-strain measurements of human and porcine corneas after ri- boflavin-ultraviolet-A-induced cross-linking // Cornea. — 2004. — Vol. 26. — P. 385-389.

6. Spoerl E. Safety of UVA-riboflavin cross-linking of the cornea // Cornea. — 2007. — Vol. 26. — P. 385-389.

7. Spoerl E., Huhle M., Seiler T. Induction of cross-links in corneal tissue // Exp. Eye Res. — 1998. — Vol. 66. — P. 97-103.

8. Tuft S. Epidemiology of Keratoconus // Cornea. — 2011. — Vol. 28. — P. 248-252.

9. Wollensak G. Crosslinking treatment of progressive keratoconus: new hope // J. Cataract Refract. Surg. — 2006. — Vol. 29. — P. 1786-1790.

10. Wollensak G. Review crosslinking treatment of progressive keratoconus: new hope // Opin Ophthalmol. — 2006. — Vol. 17. — P. 356-360.

11. Wollensak G. Gel electrophoretic analysis of corneal collagen after photody- namic cross-linking treatment // Cornea. — 2008. — Vol. 27. — P. 353-356.

12. Wollensak G. Endothelial cell damage after riboflavin-ultraviolet-A treat- ment in the rabbit // J. Cataract. Refract. Surg. — 2003. — Vol. 29. — P. 1786-190. 13. 13. Wollensak G. Significance of the lacunar hydratation pattern after corneal cross linking // Cornea. — 2010. — Vol. 29. — P. 899-903.