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Corneal Cross-linking: Intrastromal Riboflavin Concentration in Iontophoresis-Assisted Imbibition Versus Traditional and Transepithelial Techniques

2013; Elsevier BV; Volume: 157; Issue: 3 Linguagem: Inglês

10.1016/j.ajo.2013.11.018

1879-1891

Leonardo Mastropasqua, Mario Nubile, Roberta Calienno, Peter A. Mattei, Emilio Pedrotti, Niccolò Salgari, Rodolfo Mastropasqua, Manuela Lanzini,

Glaucoma and retinal disorders

Purpose To determine differences in riboflavin concentration in the anterior, intermediate, and posterior stroma after 3 corneal cross-linking imbibition techniques (standard epithelial [epi]-off, epi-on, and iontophoresis-assisted administration) of 0.1% riboflavin. Design Experimental laboratory investigation of human cadaver corneas not suitable for transplantation. Methods Ten corneas underwent imbibition with epi-on (n = 3), epi-off (n = 3), iontophoresis (n = 3), and saline exposure (control; n = 1). Femtosecond laser was used to produce 3 8-mm discs of the superficial (0-150 μm), intermediate (150-300 μm), and deep stroma (>300 μm). Riboflavin concentration was measured with high-performance liquid chromatography. The main outcome measure was riboflavin concentration at the 3 evaluated depths. Results The overall stromal concentration of riboflavin was 34.1 ± 7.1 μg/g in epi-off, 7.2 ± 3.7 μg/g in epi-on, and 15.0 ± 5.1 μg/g in iontophoresis. The mean riboflavin content in the superficial slice in the epi-off group was about 2-fold greater than that of the iontophoresis group (50.5 ± 5.3 μg/g and 23.6 ± 2.5 μg/g, respectively) and 4-fold greater than that of the epi-on group (11.7 ± 3.3 μg/g). Similar differences among the 3 groups were observed for the intermediate and posterior stromal slices, presenting an evident reduction of riboflavin concentration with increasing depth in all groups. Slice depth–dependent decrease in riboflavin concentration was statistically significant (general linear model (GLM); F1,6 = 62.265, P < .001), as was the group-dependent variation (GLM; F2,6 = 20.268, P = .002) and the slice depth group interaction (GLM; F2,6 = 18.004, P = .002). Conclusions Corneal cross-linking transepithelial iontophoresis imbibition yielded greater and deeper riboflavin saturation with respect to conventional epi-on, while maintaining the advantages of avoiding epithelial removal and shorter procedure time, but did not reach concentrations obtained with standard epi-off. To determine differences in riboflavin concentration in the anterior, intermediate, and posterior stroma after 3 corneal cross-linking imbibition techniques (standard epithelial [epi]-off, epi-on, and iontophoresis-assisted administration) of 0.1% riboflavin. Experimental laboratory investigation of human cadaver corneas not suitable for transplantation. Ten corneas underwent imbibition with epi-on (n = 3), epi-off (n = 3), iontophoresis (n = 3), and saline exposure (control; n = 1). Femtosecond laser was used to produce 3 8-mm discs of the superficial (0-150 μm), intermediate (150-300 μm), and deep stroma (>300 μm). Riboflavin concentration was measured with high-performance liquid chromatography. The main outcome measure was riboflavin concentration at the 3 evaluated depths. The overall stromal concentration of riboflavin was 34.1 ± 7.1 μg/g in epi-off, 7.2 ± 3.7 μg/g in epi-on, and 15.0 ± 5.1 μg/g in iontophoresis. The mean riboflavin content in the superficial slice in the epi-off group was about 2-fold greater than that of the iontophoresis group (50.5 ± 5.3 μg/g and 23.6 ± 2.5 μg/g, respectively) and 4-fold greater than that of the epi-on group (11.7 ± 3.3 μg/g). Similar differences among the 3 groups were observed for the intermediate and posterior stromal slices, presenting an evident reduction of riboflavin concentration with increasing depth in all groups. Slice depth–dependent decrease in riboflavin concentration was statistically significant (general linear model (GLM); F1,6 = 62.265, P < .001), as was the group-dependent variation (GLM; F2,6 = 20.268, P = .002) and the slice depth group interaction (GLM; F2,6 = 18.004, P = .002). Corneal cross-linking transepithelial iontophoresis imbibition yielded greater and deeper riboflavin saturation with respect to conventional epi-on, while maintaining the advantages of avoiding epithelial removal and shorter procedure time, but did not reach concentrations obtained with standard epi-off.