An in vitro investigation into the impact of corneal rinsing on riboflavin/UVA corneal cross-linking

Morgan, S. R., O'Brart, David P. S., Huang, Jinhai, Meek, Keith M. ORCID: https://orcid.org/0000-0002-9948-7538 and Hayes, Sally ORCID: https://orcid.org/0000-0001-8550-0108 2024. An in vitro investigation into the impact of corneal rinsing on riboflavin/UVA corneal cross-linking. Eye and Vision 11 (8) 10.1186/s40662-024-00375-4

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Abstract

Background: Corneal cross-linking (CXL) using riboflavin and ultraviolet-A light (UVA) is a treatment used to prevent progression of keratoconus. This ex vivo study assesses the impact on CXL effectiveness, as measured by tissue enzymatic resistance and confocal microscopy, of including a pre-UVA corneal surface rinse with balanced salt solution (BSS) as part of the epithelium-off treatment protocol. Methods: Sixty-eight porcine eyes, after epithelial debridement, were assigned to six groups in three experimental runs. Group 1 remained untreated. Groups 2–6 received a 16-min application of 0.1% riboflavin/Hydroxypropyl methylcellulose (HPMC) drops, after which Group 3 was exposed to 9 mW/cm2 UVA for 10 min, and Groups 4–6 underwent corneal surface rinsing with 0.25 mL, 1 mL or 10 mL BSS followed by 9 mW/cm2 UVA exposure for 10 min. Central corneal thickness (CCT) was recorded at each stage. Central 8.0 mm corneal buttons from all eyes were subjected to 0.3% collagenase digestion at 37 °C and the time required for complete digestion determined. A further 15 eyes underwent fluorescence confocal microscopy to assess the impact of rinsing on stromal riboflavin concentration. Results: Application of riboflavin/HPMC solution led to an increase in CCT of 73 ± 14 µm (P < 0.01) after 16 min. All CXL-treated corneas displayed a 2–4 fold greater resistance to collagenase digestion than non-irradiated corneas. There was no difference in resistance between corneas that received no BSS rinse and those that received a 0.25 mL or 1 mL pre-UVA rinse, but each showed a greater level of resistance than those that received a 10 mL pre-UVA rinse (P < 0.05). Confocal microscopy demonstrated reduced stromal riboflavin fluorescence after rinsing. Conclusions: All protocols, with and without rinsing, were effective at enhancing the resistance to collagenase digestion, although resistance was significantly decreased, and stromal riboflavin fluorescence reduced with a 10 mL rinse. This suggests that a 10 mL surface rinse can reduce the efficacy of CXL through the dilution of the stromal riboflavin concentration.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Optometry and Vision Sciences
Publisher:	BioMed Central
ISSN:	2326-0254
Funders:	MRC
Date of First Compliant Deposit:	13 February 2024
Date of Acceptance:	7 February 2024
Last Modified:	28 Feb 2024 12:37
URI:	https://orca.cardiff.ac.uk/id/eprint/166288

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