Transepithelial Iontophoresis-Assisted Cross Linking for Progressive Keratoconus: Up to 7 Years of Follow Up

Abstract

Purpose: To report long-term clinical results of transepithelial cross-linking with iontophoresis (I-CXL) for progressive keratoconus (KC). Methods: Nineteen eyes of 19 patients treated with I-CXL for progressive keratoconus were included in this prospective clinical study. Preoperatively and in all available follow ups (6, 12, 24, 36, 48, 60, 72 and 84 months), the following parameters were measured. Corrected distance visual acuity (CDVA), spherical equivalent and cylinder refraction, corneal topography and aberrometry (Costruzione Strumenti Oftalmici (C.S.O.), Florence, Italy), Scheimpflug tomography (OCULUS Optikgeräte GmbH; Wetzlar, Germany). Definition of progression after I-CXL was 2/3 of the following criteria: increase of “A” value, increase of “B” value, decrease of minimal thickness evaluated with the ABCD progression display above 95% confidence interval for post-CXL population when compared to the scan 12 months post-op. Results: The mean follow-up time of included patients was 63 months (range 12 to 84 months, 5 patients reached 84 months). The general linear model showed no significant change over time in CDVA, Maximum Keratometry, Thinnest point, and A, B, C values of the Belin Progression Display (p > 0.05). Conversely, comatic and high order aberrations decreased significantly over time (both p =< 0.001). Five cases (26.31%) showed significant progression after a mean of 55 months (range 36–72) of follow up. Conclusion: Our study shows the ability of I-CXL to slow down KC progression in the majority of included patients, improving high order and comatic aberrations. A 26% progression rate was reported.

Transepithelial Enhanced Fluence Pulsed Light M Accelerated Crosslinking for Early Progressive Keratoconus with Chemically Enhanced Riboflavin Solutions and Air Room Oxygen

“…Electrically assisted iontophoresis forced the permeation of the riboflavin into the stroma at a higher level compared with the original Epi-On procedures with chemically enhanced solutions, allowing an average riboflavin concentration two-fold higher throughout the whole corneal depth, with deeper and more homogeneous stromal distribution, even if its concentration was found halved compared with passive diffusion after Epi-off CXL [ 9 , 13 , 14 ]. Despite the increased intra-stromal concentration of riboflavin, the long-term follow-up of the original 5.4 J/cm 2 iontophoresis CXL (I-CXL) showed a 26% failure rate [ 17 ]. Mazzotta et al improved the results of the I-CXL method by increasing the fluence to 7 J/cm 2 , pulsing the light illumination and washing the riboflavin biofilm away from the corneal surface before starting the UV-A light, thus eliminating the riboflavin shielding effect beyond the epithelium itself, thus improving the efficacy of the treatment and the depth of the demarcation line.…”

Five-year results of iontophoresis-assisted transepithelial corneal cross-linking for keratoconus

“…In a recent study, Vinciguerra et al reported results up to 7 years in a small cohort of patients (5 patients completed the follow-up), and their findings demonstrated that I-CXL allowed to halt KC also in a long-term period [ 26 ]. The authors reported a progression of KC in 26.3% of patients using the new ABCD progression system [ 26 ]. Our results confirm such outcome in greater number of subjects observed at 5-year follow-up.…”

Expanding indications for corneal cross-linking

“…After 3 years of follow-up, this method improved visual acuity and reduced maximum keratometry (Kmax) readings, with demarcation line depth being comparable to that of epi-off cross-linking [42]. The 7-year follow-up study showed keratoconus progression in the majority of patients [43 ▪▪ ]. Recently, we presented our data on second-generation penetration enhancers for successful epi-on CXL without the use of iontophoresis or additional oxygen [44].…”