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Hidenaga Kobashi, Shunji Yunoki, Motozumi Itoi, Takeshi Ide, Jun Shimazaki, Kazuo Tsubota; Evaluation of endogenous corneal intrastromal riboflavin concentration and corneal biomechanics after violet light irradiation. Invest. Ophthalmol. Vis. Sci. 2020;61(7):2591.
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According to the previous studies, it has been considered that there is no endogenous riboflavin in the cornea. Based on the technology of corneal cross-linking (CXL), we developed the novel technology of violet light (VL) emitting glass, which is named KeraVio (ARVO 2019). We are focusing on the protocol without riboflavin drops. The purpose of this study is twofold: to quantify endogenous intrastromal concentrations of riboflavin in cornea without riboflavin drops, and to evaluate the biomechanics after VL irradiation on corneas.
Twelve human donor corneas were included in this study and randomly divided into 4 groups. The corneas underwent 4 imbibition techniques (endogenous riboflavin without drops, epithelial [epi]-on of 0.05% flavin adenine dinucleotide [FAD], epi-off of FAD, and standard CXL epi-off of 0.1% riboflavin). Corneas in FAD epi-on, FAD epi-off, and standard CXL groups were soaked with each solution instilled every 2 minutes for 30 minutes. Riboflavin concentration was measured with high-performance liquid chromatography. Ex vivo experiment involved 24 porcine corneas divided into three treatment groups and one control group. KeraVio with FAD: epi-on, VL irradiation at 310 μW/cm2 for 4.8 hours (5.4 J/cm2) and simultaneous application of FAD drops every 30-minute during VL irradiation. KeraVio without FAD: epi-on, VL irradiation only (5.4 J/cm2). Standard CXL: equivalent to Dresden protocol. Control: epi-on, no treatment of VL irradiation and riboflavin delivery. Young’s modulus at 10% strain was determined for each strip at the end of experiment.
In human corneas, the concentration of riboflavin in the stroma was 0.29 ± 0.04, 2.07 ± 1.21, 4.46 ± 5.00, and 12.49 ± 0.19 μg/g in endogenous riboflavin without drops, FAD epi-on, FAD epi-off, and Standard CXL groups, respectively. The average Young’s modulus was 682.00 ± 186.97, 684.67 ± 377.67, 715.40 ± 310.72, and 337.17 ± 156.60 kPa for KeraVio with FAD, KeraVio without FDA, standard CXL, and control groups, respectively. Significant difference was found between each treatment group and control group, whereas no significant difference between the three treatment groups.
We preliminarily identified endogenous riboflavin in human corneas without adding riboflavin drops. VL exposure itself might strengthen corneal biomechanics without the use of additional riboflavin drops.
This is a 2020 ARVO Annual Meeting abstract.
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