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Purpose: To evaluate the clinical outcomes of a new model of intrastromal corneal ring segments (ICRSs) (Keraring AS) in patients with keratoconus and quantify subsequent changes in refraction and corneal topography. Methods: This nonrandomized, single-center, retrospective observational study explores the effect of progressive thickness ICRS implantation in patients with keratoconus with a 3-month follow-up. After creating an intrastromal tunnel using a femtosecond laser, 1 or 2 ICRSs of progressive thicknesses (150/250 μm or 200/300 μm) and 160-degree arc length were implanted. Changes in uncorrected distance visual acuity, best-corrected distance visual acuity, refractive outcomes, corneal astigmatism, and maximum keratometry readings were recorded before and after surgery. Results: The study cohort consisted of 82 patients (104 eyes) with a mean age of 31.2 ± 10 years. At 3 months, ICRS implantation significantly improved uncorrected and corrected visual acuities from 0.82 to 0.46 (logarithm of the minimum angle of resolution [LogMAR]) and from 0.31 to 0.21 (LogMAR), respectively (P < 0.001). The mean spherical error reduced from −1.74 diopters (D) to −0.90 D (P < 0.001), and the mean cylindrical error reduced from −4.22 D to −2.01 D (P < 0.001). The manifest refraction spherical equivalent reduced from −3.85 D to −1.91 D (P < 0.001). All topographic parameters were reduced, including maximum keratometry (53.6 D vs. 50.3 D) and keratometric astigmatism (−4.6 D vs. −2.2 D) (P < 0.001). Conclusions: The Keraring AS provides a new, apparently safe, and effective means of improving visual acuity and reducing the refractive error and mean keratometry in eyes with asymmetric keratoconus.

Consideration of the Orbscan measurement of posterior corneal surface toricity may improve the prediction of the magnitude of refractive astigmatism.