Real-time monitoring of riboflavin concentration using different clinically available ophthalmic formulations for epi-off and epi-on corneal cross-linking

Marco Lombardo; Sebastiano Serrao; Giuseppe Massimo Bernava; Rita Mencucci; Mario Fruschelli; Giuseppe Lombardo

doi:10.1007/s00417-024-06451-8

Real-time monitoring of riboflavin concentration using different clinically available ophthalmic formulations for epi-off and epi-on corneal cross-linking

Graefes Arch Clin Exp Ophthalmol. 2024 Mar 19. doi: 10.1007/s00417-024-06451-8. Online ahead of print.

Authors

Marco Lombardo^{1

2}, Sebastiano Serrao^{3

4}, Giuseppe Massimo Bernava⁵, Rita Mencucci⁶, Mario Fruschelli⁷, Giuseppe Lombardo^{8

9}

Affiliations

¹ Studio Italiano di Oftalmologia, Via Livenza 3, 00198, Rome, Italy. mlombardo@visioeng.it.
² Vision Engineering Italy Srl, Via Livenza 3, 00198, Rome, Italy. mlombardo@visioeng.it.
³ Studio Italiano di Oftalmologia, Via Livenza 3, 00198, Rome, Italy.
⁴ Vision Engineering Italy Srl, Via Livenza 3, 00198, Rome, Italy.
⁵ CNR-IPCF, Istituto per i Processi Chimico-Fisici, Viale F. Stagno D'Alcontres 37, 98158, Messina, Italy.
⁶ SOD Oculistica, AOU Careggi, Università di Firenze, Largo Brambilla 3, 50134, Florence, Italy.
⁷ Sezione Oftalmologia, Policlinico Santa Maria alle Scotte, Università di Siena, Dip. Scienze mediche-chirurgiche e neuroscienze, Viale Bracci, 53100, Siena, Italy.
⁸ Studio Italiano di Oftalmologia, Via Livenza 3, 00198, Rome, Italy. giuseppe.lombardo@cnr.it.
⁹ CNR-IPCF, Istituto per i Processi Chimico-Fisici, Viale F. Stagno D'Alcontres 37, 98158, Messina, Italy. giuseppe.lombardo@cnr.it.

PMID: 38502352
DOI: 10.1007/s00417-024-06451-8

Abstract

Purpose: To assess the feasibility of theranostics to determine the riboflavin concentration in the cornea using clinically available ophthalmic formulations during epithelium-off (epi-off) and transepithelial (epi-on) corneal cross-linking procedures.

Methods: Thirty-two eye bank human donor corneas were equally randomized in eight groups; groups 1 to 3 and groups 4 to 8 underwent epi-off and epi-on delivery of riboflavin respectively. Riboflavin ophthalmic solutions were applied onto the cornea according to the manufacturers' instructions. The amount of riboflavin into the cornea was estimated, at preset time intervals during imbibition time, using theranostic UV-A device (C4V CHROMO4VIS, Regensight srl, Italy) and expressed as riboflavin score (d.u.). Measurements of corneal riboflavin concentration (expressed as µg/cm³) were also performed by spectroscopy absorbance technique (AvaLight-DH-S-BAL, Avantes) for external validation of theranostic measurements.

Results: At the end of imbibition time in epi-off delivery protocols, the average riboflavin score ranged from 0.77 ± 0.38 (the average corneal riboflavin concentration was 213 ± 190 µg/cm³) to 1.79 ± 0.07 (554 ± 103 µg/cm³). In epi-on delivery protocols, the average riboflavin score ranged from 0.17 ± 0.01 to 0.67 ± 0.19 (corneal riboflavin concentration ranged from 6 ± 5 µg/cm³ to 122 ± 39 µg/cm³) at the end of imbibition time. A statistically significant linear correlation (P ≤ 0.05) was found between the theranostic and spectrophotometry measurements in all groups.

Conclusions: Real-time theranostic imaging provided an accurate strategy for assessing permeation of riboflavin into the human cornea during the imbibition phase of corneal cross-linking, regardless of delivery protocol. A large variability in corneal riboflavin concentration exists between clinically available ophthalmic formulations both in epi-off and epi-on delivery protocols.

Keywords: Corneal cross-linking; Riboflavin; Theranostics.

Abstract

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