Iontophoretic Corneal Collagen Cross Linking (I-Cxl) With Accelerated Protocol: Refractive And Tomographic Results At 72 Months

The aim of the study is to evaluate the effectiveness on refractive and tomographic parameters of i-CXL-TE associated with an accelerated protocol of UV irradiation at 10 mW/cm2 for 9 minutes in pediatric and young adult patients with progressive keratoconus. We evaluated the role of this technique in patients aged between 12 and 35 years with tomographic progression (increase in Kmax >1.5 diopters or reduction in the thinnest point >20 microns) or increase in refraction values ​​>0.75 diopters cylindrical in the previous 6 months. The results at 72 months of follow up and side effects, if any, have been reported.

Salerno Hospital University

121 eyes of 88 patients with topographic, pachymetric, or refractive progression of KC within the previous 6 months underwent iCXL-TE from 01.01.2016 to 31.12.2017, were enrolled in the study. Exclusion criteria: diabetes mellitus, immune system systemic disease, herpetic keratitis, corneal scarring, thinnest point of the cornea <380 microns, endothelial cell density<1800/mm2, pregnancy and breastfeeding. Epi-on imbibition was performed with a dedicated 0.1% hypotonic riboflavin solution and iontophoretic method for 5', followed by irradiation with the accelerated 10mW/cm2 protocol for 9'. Clinical evaluation and tomographic follow-up using Scheimpflug camera was performed at 1, 3, 6, 12, 24, 36, 48, 60, and 72 months.

The average increase in Kmax values ​​was +1.87 +/- 0.36 D in the 6 months prior to treatment. Post-treatment average Kmax values ​​decreased by 0.56 +/- 0.79D, -0.91 +/- 0.83D, -1.11 +/-1.21D, -1.23 +/-1.31D, -1.17 +/- 1.18D, -1.01 + / -1.21, -0.91+/-1.18D at 6, 12, 24, 36, 48, 60, 72 months respectively; 9 eyes had further progression and required retreatment. In 71% of eyes there was a reduction in Kmax values ​​at 72 months, in 82% of eyes there was a significant improvement (p<0.05) in visual acuity (BSCVA -0.17 +/-0.15); endothelial count and tone unchanged during the study. We had a case of moderate haze, resolved within six months of treatment and a flare-up of herpes simplex; we did not observe any other side effects.

I-CXL-TE treatment with an accelerated protocol was effective in arresting or slowing down the worsening of keratoconus at the 72-month follow-up and resulted in a statistically significant improvement in average visual acuity and a reduction in Kmax in approximately 3/4 of treated patients, despite having experienced a significant worsening in the six months preceding treatment. The fast execution time of the iontophoretic procedure, the reduced invasiveness and the absence of significant side effects make it a valid alternative to epi-off CXL. For its optimal compliance it must be considered with great interest especially in pediatric and young adult patients.