• Transepithelial CXL With Iontophoresis for Keratoconus: Two-Year Outcomes

    By Lynda Seminara
    Selected By: Deepak P. Edward, MD

    Journal Highlights

    Journal of Cataract & Refractive Surgery
    2019;45:992-1000

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    Iontophoresis is a noninvasive technique for delivering a charged substance intothe corneal stroma by repulsive electromotive force. Lombardo et al. developed a slightly modified transepithelial ion­tophoresis (T-ionto) corneal cross-link­ing (CXL) technique and compared this procedure to standard CXL. Two years following treatment, the outcomes of T-ionto CXL were comparable to those of standard CXL for halting keratoco­nus progression, despite less corneal apex flattening with the new technique.

    In this single-site trial, participants’ eyes were assigned randomly to receive T-ionto CXL (n = 22) or standard CXL (n = 12). Outcome measures included corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), manifest refraction spheri­cal equivalent, maximum simulated keratometry (K), corneal higher-order aberrations, central corneal thickness, and endothelial cell density. All out­comes were assessed at various intervals through 24 months post-op.

    By two years, mean maximum K had flattened by –1.05 ± 1.20 D in the T-ionto CXL group (p = .07) and by –1.51 ± 0.89 D in the control group (p < .001). Two eyes that received T-ionto CXL showed maximum K steepening of >1.0 D by 24 months; this did not occur in any control eye. The mean change in CDVA was –0.08 ± 0.15 logMAR in T-ionto CXL eyes (p = .04) and –0.02 ± 0.06 logMAR in standard CXL eyes (p = .34). By 24 months, UDVA improved from 0.80 ± 0.19 logMAR to 0.48 ± 0.36 logMAR in T-ionto CXL eyes (p < .001) and from 0.65 ± 0.30 logMAR to 0.32 ± 0.29 logMAR in eyes that received standard CXL (p = .01). The average decrease in myopic defocus was significant in both groups (+0.81 D; p < .05).

    There were no significant between-group differences in the various out­come measures at 24 months. Corneal higher-order aberration and endotheli­al cell density values did not change sig­nificantly in either group, and central corneal thickness was nearly unchanged from baseline. The cornea was clear in all 22 eyes that underwent T-ionto CXL; haze was present in two control eyes (16.66%).

    In summary, the favorable outcomes observed at one year remained stable for both procedures through two years of follow-up. Standard CXL produced greater flattening of the corneal apex.

    The original article can be found here.