Private practice.
Prospective case series.
This study comprised patients who had primary keratoconus or keratectasia after laser in situ keratomileusis (LASIK); none wore contact lenses. Rings were implanted through tunnels created manually or with a femtosecond laser. All eyes had clear visual axes and corneal thickness over 450 μm at the incision site. Preoperative and postoperative pachymetry images were acquired. Results were analyzed using a matched-pair t test and the Kolmogorov-Smirnov test.
Twenty-nine eyes (24 patients; mean age 30.1 years ± 10.6 [SD]) were evaluated. The ICRS significantly increased uncorrected and corrected visual acuities from 0.05 to 0.16 and from 0.17 to 0.5, respectively (z = 4.7, P < .001). They reduced the median spherical error from −4.0 to −0.5 diopters (D) (P < .001) and median cylindrical error from −4.4 to −2.5 D (P < .001). All topographic parameters were reduced, including maximum keratometry (K) (49.4 D versus 45.1 D), minimum K (49.4 D versus 45.1 D), mean K (51.4 D versus 48.4 D), astigmatism (−2.0 D versus −0.5 D), and asphericity (eccentricity 0.49 versus 0.23) (all P < .001).
The ICRS provided topographic and visual improvement in keratoconus and post-LASIK keratectasia. Variance in surgical outcomes with manual versus femtosecond tunneling and the effect of different ring sizes are yet to be studied.
None of the authors has a financial or proprietary interest in any material or method mentioned.