Surgical Options for the Refractive Correction of Keratoconus: Myth or Reality

Abstract

Keratoconus provides a decrease of quality of life to the patients who suffer from it. The treatment used as well as the method to correct the refractive error of these patients may influence on the impact of the disease on their quality of life. The purpose of this review is to describe the evidence about the conservative surgical treatment for keratoconus aiming to therapeutic and refractive effect. The visual rehabilitation for keratoconic corneas requires addressing three concerns: halting the ectatic process, improving corneal shape, and minimizing the residual refractive error. Cross-linking can halt the disease progression, intrastromal corneal ring segments can improve the corneal shape and hence the visual quality and reduce the refractive error, PRK can correct mild-moderate refractive error, and intraocular lenses can correct from low to high refractive error associated with keratoconus. Any of these surgical options can be performed alone or combined with the other techniques depending on what the case requires. Although it could be considered that the surgical option for the refracto-therapeutic treatment of the keratoconus is a reality, controlled, randomized studies with larger cohorts and longer follow-up periods are needed to determine which refractive procedure and/or sequence are most suitable for each case.

Three-year follow-up of intrastromal corneal ring segment implantation in central keratoconus with regular astigmatism: ‘Bow-tie’ shape

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] The results of this procedure may depend on multiples variables, some related to the surgery and/or implant and others related to the preoperative characteristics of the keratoconus. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] It is widely known that keratoconus characteristics do not follow a fixed pattern and may vary (shape, higher order aberrations, refractive error, among others). Consequently, to analyse the results of the procedure properly, it would be interesting to assess the same ICRS implantation protocol/nomogram in eyes that met the same preoperative characteristic.…”

“…The corrective effect depends on the thickness, arc length, and apical diameter of the segments and the number of segments implanted (one or two). [1][2][3][4][5][6][7] The Ferrara-type ICRS (AJL Ophthalmic, Spain) is available with an apical diameter of 5.0 or 6.0 mm, with variable thickness (0.15 mm to 0.30 m in 0.05 mm steps) and arc length (90°, 120°, and 150°, 210°). This implies that the surgeon should choose from among a variety of possible combinations to achieve the desired corrective effect.…”

Intrastromal corneal ring segment implantation in paracentral keratoconus with perpendicular topographic astigmatism and comatic axis

“…Intrastromal corneal ring segments (ICRS) implantation has been widely recognized as a safe and effective procedure to reshape the corneal morphology in keratoconus and consequently improving the visual quality. [1][2][3] The ICRS are implanted within the corneal stroma and its correction effect depends on the arc length and thickness of the ICRS, the optical diameter and its precise implantation in the corneal stroma. [1][2][3][4] Furthermore, the effect of the ICRS on the corneal morphology also depends on the corneal axis where the ICRS are implanted.…”

“…[1][2][3] The ICRS are implanted within the corneal stroma and its correction effect depends on the arc length and thickness of the ICRS, the optical diameter and its precise implantation in the corneal stroma. [1][2][3][4] Furthermore, the effect of the ICRS on the corneal morphology also depends on the corneal axis where the ICRS are implanted. ICRS are generally implanted at the flattest meridian, aiming to decrease the curvature in the steeper meridian and consequently reducing the refractive cylinder.…”

Long-Term Follow-up of Intrastromal Corneal Ring Segment Implantation in Pediatric Keratoconus

“…Beyond keratoconus stabilization, the other important challenge is to improve visual quality. Intrastromal corneal ring segment (ICRS) implantation has proven to be sound and efficacious in mitigating corneal abnormalities and improving visual quality in adult patients with this disease, [10][11][12] but few studies have dealt with this procedure for visual rehabilitation in children. 13,14 A recent study 13 has evaluated the safety and visual results of ICRS implantation, followed by CXL in child keratoconus, and the findings suggest that ICRS implantation is safe and effective for visual rehabilitation in this segment of the population.…”