Interlamellar cohesion after corneal crosslinking using riboflavin and UVA

Gregor Wollensak (1) , Eberhard Spörl (2) , Cosimo Mazzotta (3) , Thomas Kalinski (4) , Saadettin Sel (5)

1 Eye Laser Institute, Halle,
2 Department of Ophthalmology, Technical University of Dresden
3 UNISI - Università degli Studi di Siena = University of Siena
4 Department of Pathology, University of Magdeburg, Magdeburg, Germany
5 Department of Ophthalmology, Martin-Luther-University, Halle, Germany,

ABSTRACT Aims: Collagen crosslinking (CXL) treatment of progressive keratoconus using the photosensitizer riboflavin and UVA light of 370 nm wavelength has been shown to increase significantly the tensile strength of corneal collagen by about 300%. In keratoconus, interlamellar and interfibrillar slippage have been proposed as pathogenetic mechanism. Therefore, the aim of this study was to assess the impact of CXL on the interlamellar cohesive force. Methods: 72 post mortem porcine eyes were divided into six different treatment groups:The untreated control group, the standard crosslinking group, the hypoosmolar crosslinking group, the stromal swelling, the formaldehyde group, and the á-amylase group. An anterior 9 x 4 mm strip of 400 µm thickness was prepared using a lamellar rotating microkeratome. For interlamellar cohesive force measurements a splitting plane was created at 50% flap thickness. Force-distance profiles were recorded using a microcomputer-controlled biomaterial testing machine. Results:The mean interlamellar cohesive force was 0.24 N/mm in the untreated control group, 0.26 N/mm in the standard crosslinking group, 0.25 N/mm in the hypoosmolar crosslinking group, 0.23 N/mm in hydrated corneas, 0.27 N/mm in the formaldehyde group without statistically significant difference. Only the values of the á-amylase group were statistically significantly lowered by 31.5% to 0.16 N/mm. Conclusions: Surprisingly, corneal crosslinking does not increase the interlamellar cohesive force. In the á-amylase group the cohesive force was mainly decreased due to the digestion of proteoglycans. Crosslinking seems to stabilize only inter- and intrafibrillar but not interlamellar cohesion.

Mots clés: Cornea; Intraocular pressure; Degeneration; Treatment other; Experimental &#8211 animal models

Gregor Wollensak, Eberhard Spörl, Cosimo Mazzotta, Thomas Kalinski, Saadettin Sel. Interlamellar cohesion after corneal crosslinking using riboflavin and UVA. British Journal of Ophthalmology, 2011, 95 (6), pp.876. ⟨10.1136/bjo.2010.190843⟩. ⟨hal-00616883⟩