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.