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    Surgical management of keratoconus: Rings and more

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    Although corneal crosslinking (CXL) has vastly improved the treatment paradigm of keratoconus, the procedure only stabilizes the progression of the disease but does not restore patients' vision. Patients who have been treated with corneal crosslinking or older patients in whom the disease is stable are thus left wanting for improved visual function.

    As a result these patients show a strong interest in surgical visual revalidation techniques. This is especially true of patients who are intolerant to contact lenses. My strategy in managing such patients is to target emmetropia, and I use a variety of approaches to achieve this goal depending on each patient's unique situation.

    Weighing the pros and cons of visual revalidation techniques

    I currently use three different approaches to visual revalidation in keratoconus patients — phakic intraocular lenses (IOLs; Artisan IOL, Ophtec, Groningen, The Netherlands), topography guided photorefractive keratectomy (TG-PRK, performed with the WavelightEyeQ400 Excimer Laser, Alcon, Fort Worth, Texas, USA and some with the Schwind Amaris 750S Excimer Laser, Schwind, Kleinostheim, Germany), and intracorneal ring segments (ICRS; Keraring, Mediphacos, Minas Gerais, Brazil). Each of these technologies has its own set of pros and cons and the final choice of treatment modality will depend on the patient's clinical parameters such as corneal thickness, spherical equivalent, astigmatism and topography.

    For instance, although TG-PRK has the advantage that it recentres the conus making the cornea more regular, it is limited by the requirement that it must be performed either after or simultaneously with CXL and that it is non-reversible. Furthermore, general guidelines recommend that surface ablation must not be performed deeper than 50 μm, which limits the extent of ametropia that can be corrected.

    With phakic IOLs, high myopia and astigmatism can be corrected and the procedure is theoretically reversible, however, it is an invasive intraocular technique in which the cornea remains unchanged. Furthermore, preoperative CXL is required in young patients and those with progressive keratoconus.

    ICRS are a less invasive treatment option that are also easily reversible. They can be used to treat high levels of myopia and astigmatism and also recentre the conus and make the cornea regular. Some surgeons suggest that ICRS can be implanted without prior CXL, even in young or progressive keratoconus patients; however, I prefer to use CXL to stabilize the keratoconus before implanting the ICRS. A seeming disadvantage of ICRS is that they often cause visual symptoms such as halos, although most of my patients claim to not be too disturbed by them.

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    Dr Jerome C. Vryghem
    Dr Jerome C. Vryghem is medical director at Brussels Eye Doctors, Brussels, Belgium. He may be reached by E-mail: [email protected]

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