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    A 3-step treatment for keratoconus

    CXL and topo-guided PRK or toric phakic lens implantation after corneal ring placement


    The arrival of advanced therapeutic modalities for keratoconus has provided ophthalmologists with a growing menu of treatment options, which promise to delay or halt progression of the disorder, and improve refractive outcomes. While spectacles, contact lenses and penetrating keratoplasty are the traditional go-to solutions, and continue to play a vital role in the management of keratoconus, there is growing interest in the more 'high-tech' options such as corneal crosslinking (CXL), intrastromal corneal ring segments (ICRs), toric phakic lenses (ICLs) and topo-guided photorefractive keratectomy (PRK).

    Which treatment, when?

    Along with the availability of newer, more sophisticated options for the management of keratoconus comes the challenge of determining which treatment to use and when to use it to deliver the best possible outcomes for each patient.

    Although treatment choice may be influenced by surgeon and patient preference, the strategy employed, largely depends on the stage of keratoconus. For example, a patient with form fruste keratoconus, may require only rigid contact lens and regular monitoring with corneal topography. However, in patients with established keratoconus without progression, but with loss of corrected visual acuity and evidence of surface irregularity, implanting an ICR such as the Keraring (Mediphacos, Belo Horizonte, Brazil) would be considered prudent by many refractive surgeons.

    While ICR implantation alone helps to reduce corneal steepening and reduce refractive errors, many ophthalmologists recognize that combining treatments may help to further improve vision and slow progression. Further, a combination procedure is necessary in patients with loss of visual acuity and evidence of progression.

    Figure 1: Examples of Three-Step Procedures Employed in the Treatment of Keratoconus
    ICR implantation followed by CXL is often the strategy of choice for such patients; however, in some cases, for example, in individuals with high refractive errors, a triple procedure, combining an ICR, CXL and a toric ICL or topo-guided transepithelial PRK, may be employed (Figure 1). Moreover, evidence suggests that ICR implantation and topography-guided transepithelial PRK may help to optimize the effects of CXL treatment.1–5

    The effect of a triple procedure on refractive outcomes: Our experience

    At the World Eye Hospital in Istanbul, Turkey, we conducted a prospective, case-series study, on 16 eyes of 10 patients with progressive keratoconus (defined as an increase in the cone apex keratometry of 0.75 D or alteration of 0.75 D in the spherical equivalent [SE] refraction in a period of at least 6 months), to evaluate the effect of a triple procedure comprising Keraring ICR implantation followed by CXL and topo-guided transepithelial PRK on visual acuity.

    The mean interval between Keraring ICR implantation and CXL was 7 months, and the mean interval between CXL and topo-guided transepithelial PRK was 8.2 months. Postoperative visual acuity and pachymetry/topography results were evaluated after each stage of treatment, with a mean follow-up time of 6.2 months.

    Findings showed that the mean LogMAR uncorrected distance visual acuity (UDVA) and mean corrected distance visual acuity (CDVA) were significantly improved (p < 0.05) from 1.14 ± 0.36 and 0.75 ± 0.24 preoperatively to 0.25 ± 0.13 and 0.13 ± 0.06, respectively, after completion of the three-step procedure. Uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) also improved, from 0.05 and 0.2, preoperatively, to 0.7 and 0.9, respectively, after the final procedure. Moreover, both UDVA and CDVA, as well as UCVA and BCVA also improved significantly after the ICR implantation, indicating that the Keraring is an effective method for improving visual acuity in patients with progressive keratoconus.

    Table 1: Preoperative, Postoperative ICR, Postoperative CXL, and Postoperative PRK Enhancement Data
    Data also showed that the mean SE refraction was significantly reduced (p < 0.05) from –5.66 ± 5.63 D preoperatively to –0.98 ± 2.21 D after the three-step procedure. In addition, mean SE refraction was improved significantly in every step of the combined treatment, but mean cylinder improved significantly only after Keraring implantation and topography-guided transepithelial PRK. Mean steep and flat keratometry values were significantly reduced (p < 0.05) from 54.65 ± 5.80 D and 47.80 ± 3.97 D preoperatively to 45.99 ± 3.12 D and 44.69 ± 3.19 D after the three-step procedure, respectively; mean keratometry readings also improved significantly after every step of the procedure (Table 1).6

    Figure 2: Reduction in mean SE refraction and refractive astigmatism following ICR + CXL + pIOL
    If a patient needs high refractive and astigmatic correction (more than 7 D) after ICR followed by CXL, I implant a toric ICL. We recently conducted a case series study to evaluate a staged triple procedure using this approach, i.e., Keraring ICR implantation followed by CXL and then toric ICL placement in 14 eyes of 9 patients with progressive keratoconus. After the combined treatments (with a minimum 6 months between procedures), the mean decimal UDVA and mean decimal CDVA were significantly improved from 0.01 and 0.14, respectively, to 0.44 and 0.57, respectively (p < 0.0001). Improvements in UCVA and BCVA were also seen with patients achieving a UCVA of 0.46 and a BCVA of 0.58 after completion of the three-step procedure, compared with 0.01 and 0.16, respectively, before treatment initiation. Findings also demonstrated that the mean SE refraction decreased after each stage of the triple procedure, and from –16.40 D ± 3.56 (range –11.50 to –22.50 D) to –0.80 D ± 1.02 (range –2.00 to +2.00 D) after the combined treatments (p < 0.0001) (Figure 2). The mean refractive astigmatism decreased from –4.73 D ± 1.32 (range –3.00 to –7.00 D) to –0.96 D ± 0.35 (range –0.50 to –1.50 D, p < 0.0001) (Figure 2), while the mean steep and mean flat keratometry values reduced from 60.57 D and 56.16 D, to 54.48 D and 53.57 D (p < 0.0001), respectively, following the triple procedure. No intraoperative or postoperative complications occurred.7


    Dr Efekan Couskunseven
    Dr Efekan Ços¸kunseven is head of the Department of Refractive Surgery at the World Hospital in Istanbul, Turkey. He can be reached by ...

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