ESCRS - FP02.07 - The Enzymatic Resistance Effect Of High-Fluence Accelerated Corneal Cross-Linking With Rose Bengal/Green Light Is Oxygen-Independent

The Enzymatic Resistance Effect Of High-Fluence Accelerated Corneal Cross-Linking With Rose Bengal/Green Light Is Oxygen-Independent

Published 2023 - 41st Congress of the ESCRS

Reference: FP02.07 | Type: Free paper | DOI: 10.82333/mks6-qz87

Authors: M. Enes Aydemir* 1 , Nikki L. Hafezi 1 , Emilio A. Torres-Netto 1 , Nanji Lu 1 , Mark Hillen 1 , Farhad Hafezi 2

1Ophthalmology,ELZA Institute AG,Dietikon,Switzerland, 2Ophthalmology,ELZA Institute AG,Dietikon,Switzerland;Ocular Cell Biology Laboratory,University of Zurich,Zurich,Switzerland

Purpose

Corneal cross-linking (CXL) with rose Bengal and green light induces several effects in the cornea, including 1) biomechanical stiffening, 2) increased resistance to enzymatic digestion and 3) generation of reactive oxygen species (ROS). Little is known about the effect of oxygen on the resistance to enzymatic digestion in rose Bengal-mediated CXL. Here, we examined rose Bengal CXL-induced enzymatic resistance in the absence of oxygen.

Setting

Laboratory study. ELZA Institute, Dietikon, Switzerland and Laboratory for Ocular Cell Biology, CABMM, University of Zurich.

Methods

106 ex vivo porcine corneas were assigned to 5 groups. Group 1 served as control (abrasion/Rose Bengal application). Group 2 and 3 received rose bengal CXL treatment at 522 nm in a normal room atmosphere at 21% of oxygen (10 J/cm2, 11 min 7 sec @ 15mW/cm2 and 15 J/cm2, 8 min @ 30 mW/cm2, respectively), whereas groups 4 and 5 were treated in the absence of oxygen (nitrogen chamber). All corneas were digested in 0.3% collagenase A solution. Time to total dissolution was assessed.

Results

The mean times to digestion in Groups 1 through 5 were: 31.21 ± 3.84 h, 33.7 ± 2.38 h, 33.74 ± 1.37 h, 34.39 ± 1.85 h and 33.86 ± 2.01 h, respectively.

All groups had significantly higher digestion resistance than the non-irradiated rose bengal control group (Group 1) (groups 2 to 5: P = 0.012, P = 0.017, P > 0.001, P = 0.008, respectively). However, there was no significant difference in the mean time to digestion across all the experimental groups, irrespective of fluence delivered or the presence of oxygen.

Conclusions

High-fluence accelerated rose bengal/green light CXL protocols (10 J/cm² and 15 J/cm²) render ex vivo porcine corneas significantly more resistant to enzymatic digestion when compared to non-irradiated control corneas. This effect seems to be oxygen-independent.