Singlet oxygen formation during accelerated and hyperaccelerated corneal cross-linking: in vitro study

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Photochemistry

Background:

• Riboflavin and ultraviolet-A (UVA) crosslinking is a standard therapy.
• Evaluating singlet oxygen (¹O₂) production is crucial for understanding crosslinking efficacy.
• Oxygen assistance's role in ¹O₂ generation during various crosslinking protocols requires further investigation.

Purpose of the Study:

• To quantify singlet oxygen (¹O₂) production during oxygen-assisted riboflavin UVA crosslinking.
• To compare ¹O₂ generation across standard, accelerated, and hyper-accelerated crosslinking procedures with and without oxygen.
• To assess the impact of oxygen flow rates on ¹O₂ generation using 1,3 diphenylisobenzofuran (DPBF) photo-oxidation.

Main Methods:

• Irradiation of riboflavin solutions with UVA light (365 nm) under varying oxygen flow rates (0-8 L/min).
• Quantification of ¹O₂ production by measuring the decrease in DPBF absorbance.
• Testing standard (3 mW), accelerated (9 mW), and hyper-accelerated (30 mW) UVA irradiances with and without oxygen supplementation.

Main Results:

• Accelerated crosslinking with 2 L/min oxygen significantly increased DPBF absorbance decrease compared to the Dresden protocol (p=0.014).
• The Dresden protocol showed greater DPBF absorbance decrease than all groups except accelerated crosslinking with 2 L/min oxygen (p<0.001).
• Oxygen-assisted hyper-accelerated crosslinking demonstrated significantly higher DPBF reduction than standard crosslinking without oxygen (p<0.001).

Conclusions:

• Oxygen supplementation can elevate singlet oxygen generation to levels comparable to the Dresden Protocol in accelerated crosslinking.
• Increased singlet oxygen generation with oxygen supplementation suggests a promising approach for reducing crosslinking therapy duration.
• Further research into oxygen-assisted protocols may optimize riboflavin UVA crosslinking efficiency.