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.
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.
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
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