Seiler, Theo G.; Komninou, Maria Angeliki; Nambiar, Malavika H.; Schürch, Kaspar; Frueh, Beatrice E.; Büchler, Philippe (2021). Oxygen kinetics during corneal crosslinking with and without supplementary oxygen. American journal of ophthalmology, 223, pp. 368-376. Elsevier Science 10.1016/j.ajo.2020.11.001
|
Text
1-s2.0-S0002939420306292-main.pdf - Accepted Version Available under License Publisher holds Copyright. Download (6MB) | Preview |
PURPOSE
To measure and simulate oxygen kinetics during corneal crosslinking (CXL) at different irradiances with and without supplementary oxygen.
DESIGN
Experimental, laboratory study.
METHODS
In de-epithelialized porcine eyes, a femtosecond-laser generated tunnel was used to place a fiber-probe in corneal depths of 100, 200 and 300μm to measure the local oxygen concentration. After riboflavin imbibition, the corneas were irradiated at 3, 9, 18 and 30mW/cm2 while the oxygen concentration was measured. All experiments were performed under normoxic (21%) and hyperoxic (>95%) conditions. The obtained data were used to identify parameters of a numerical model for oxygen consumption and diffusion.
RESULTS
The equilibrium stromal oxygen concentration under atmospheric oxygen at 3mW/cm2 was 2.3% in 100μm decreasing to <1% in 300μm. With 9, 18 and 30mW/cm2, no oxygen was available in 200μm respectively 100μm or deeper. Using a hyperoxic environment, the concentration was 50% using 3mW/cm2 in 100μm, decreasing to 40% in 300μm. At 9mW/cm2 the concentrations were 5%, 3% and 1% in 100, 200 and 300μm, respectively. Using 18 and 30mW/cm2 all oxygen was depleted at 100μm, however, oxygen half-lives were longer at 18mW/cm2 than at 30mW/cm2. The oxygen model was able to reproduce the experiments and indicated an exponential decay with increasing distance to the anterior surface.
CONCLUSION
Supplementary oxygen increases the oxygen-availability during CXL. At higher irradiances, supplementary oxygen is beneficial and eliminates the bottleneck of oxygen allowing a potentially more efficient crosslinking. The calibrated numerical model can quantify the spatial oxygen concentration related to different scenarios such as irradiance or environmental oxygen concentration.
Actions (login required)
 |
Edit item |