Aim
To evaluate the biomechanical stability of the corneal scar treating with riboflavin and ultraviolet A (UVA).
Conclusion
CXL with riboflavin/UVA at seven days after suturing improved the biomechanical properties of corneal scars most effectively in the present study.
Methods
Totally 86 New Zeal rabbits were divided into control group (group A, n=8) and trauma groups [group B (n=27), group C (n=24) and group D (n=27)]. Then groups B, C and D were divided into three sub-groups according to the time points of sacrifice, i.e. groups Ba, Ca and Da (4wk, n=8); Bb, Cb and Db (6wk, n=8); Bc (n=11), Cc (n=8) and Dc (8wk, n=11). The right corneas of these 78 rabbits in the trauma groups were penetrated. Group B were only sutured. Group C were treated with corneal cross-linking (CXL) immediately after suturing. Group D were treated with CXL seven days after suturing. The corneal scar strips of 4.0×10.0 mm2 were cut and the stress and Young's modulus at 10% strain were evaluated. Samples from the three rabbits of group Bc and three of group Dc were used to measure the expression of alpha smooth muscle action (α-SMA).
Results
The mechanical strength of the corneal scar increased with time, and was strongest at 8wk after the injury. The ultimate stress of corneal scar (group D) were 2.17±0.52 MPa, 2.92±0.63 MPa, and 4.21±0.68 Mpa at 4wk, 6wk and 8wk, respectively; Young's modulus were 10.94±1.57 MPa, 11.16±2.50 MPa, and 13.36±2.10 Mpa, which were higher than that of other groups except for normal control. The expression of α-SMA in group B and group D were 0.28±0.11 and 0.65±0.20, respectively, and the difference was statistically significant (P=0.048).