Immediate Effect of Ultraviolet-A Collagen CXL Therapy on Biomechanics and Histology of Human Cornea
Abstract
Purpose
To evaluate the immediate effect of the CXL treatment on the biomechanical properties and histological microstructure of healthy human corneal tissue. With this purpose, in vitro mechanical tests and histological observation of cross-linked and untreated human corneal tissue were performed.
Methods
Mechanical tensile test and histological analysis were performed in de-epithelialized healthy human corneal tissue treated with riboflavin solution (0.01% riboflavin-5-phosphate and 20% dextranT-500) – 30 min UVA irradiation (treated sample TS). A similar study was performed to untreated de-epithelialized healthy human corneal tissue (control sample, CS). Both histological and mechanical analyses were performed immediately after treatment.
Results
The analysis of the stress-strain curves showed a different corneal response between treated (TS) and untreated (CS) samples. TS showed a stiffer behaviour than CS. The treated corneal tissue (TS) resulted 1.8, 1.6, 1.7 and 1.5 fold stiffer than the untreated sample (CS) at 6, 8, 10 and 12% stretch, respectively. The histological analysis of TS showed an increased fibrillar density with decrease of interlamellar space in comparison with CS. Keratocyte apoptosis was observed in TS even at deep stromal level.
Conclusions
The UVA-induced CXL has an immediate biomechanical and histological effect over the treated healthy human corneal tissue. Stiffening of the tissue, keratocyte apoptosis and stromal compacting were observed.
