Abstract
Purpose :
The overall treatment time of standard CXL takes around 60 to 120 minutes but risks infection and corneal dehydration. There are two types of CXL pathways, with Type-II CXL requiring oxygen. However, the dissolved oxygen in the cornea has limited quantity, thus limiting the effect from Type-II CXL. To reduce the overall treatment time while maintaining efficacy, we propose to improve the Type-II CXL contribution by introducing dissolved oxygen during the treatment. In this study, we assess the enhancement of the cornea's mechanical properties with oxygen-assisted CXL (O2CXL).
Methods :
12 Porcine eyes were obtained from a slaughterhouse 6-hour postmortem and divided into two groups: standard CXL and O2CXL groups. Riboflavin solution at a concentration of 0.146% was used. The corneal portion of the whole globe was submerged in the riboflavin solution for 30 minutes before the treatment. The riboflavin solution used for O2CXL was saturated with oxygen for 20 minutes prior to cornea staining, and oxygen supply was maintained during the 30 minutes staining process. Before each CXL treatment, two identical cornea strips were dissected along the short axis. Given the large intra-sample variation of mechanical properties, we chose one strip as a reference (no CXL treatment). The other cornea strip underwent CXL treatment. All corneal strips were treated with 365nm UV light at 3 mW/cm2 for 30 minutes. Uniaxial tensile testing was performed on both reference and treated corneal strips to assess the biomechanical enhancement. We determined the tangential modulus at 10% strain and calculated enhancement for each group.
Results :
At 10% strain, the treated corneal strip with O2CXL (σmean=1.22±0.43MPa) resulted in an average of 69.1%±29.5% increase in tangential modulus compared to the non-treated samples (σmean=0.70±0.25MPa). The treated samples with standard CXL (σmean=1.45±0.13MPa) showed an average improvement of 26.1%±9.03% compared to the non-treated samples (σmean=1.06±0.19MPa). Overall, O2CXL is 1.6 times more effective than the standard CXL.
Conclusions :
O2CXL showed a significant increase in biomechanical enhancement compared to the standard CXL. Such enhancement could be attributed to the supplied oxygen, which prolonged the Type-II CXL, thus improving its stiffening effect. O2CXL should be further investigated to optimize the current CXL procedure, such as reducing the overall treatment time.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.