Refractive and topographic effects of single-segment intrastromal corneal ring segments in eyes with moderate to severe keratoconus and inferior cones

Abstract

To evaluate the efficacy and safety of a single intrastromal corneal ring segment (ICRS) (450 μm Intacs SK) in moderate to severe keratoconic eyes with an inferiorly located cone and a noninvolved center. Ophthalmology Department, American University of Beirut Medical Center, Beirut, Lebanon. Retrospective case series. The uncorrected (UDVA) and corrected (CDVA) distance visual acuities, central and inferior maximum topographic keratometry (K) values, manifest cylinder, and spherical equivalent (SE) were recorded preoperatively and 1 week and 1, 3, and 6 months postoperatively. Thirty eyes were studied. The mean age was 29.6 years ± 8.0 (SD). The mean preoperative UDVA and CDVA were 20/86 and 20/42, respectively. The mean center K was 49.14 ± 4.39 diopters (D); the mean maximum K, 56.78 ± 6.02 D; and the mean center K - maximum K, -7.45 ± 5.61 D. The mean SE and cylinder were -2.24 ± 2.32 D and -4.33 ± 1.43 D, respectively, with sphere ranging from +2.00 to -18.00 D. At 6 months, the UDVA improved to 20/32. The mean SE was -1.02 ± 2.04 D (P = .0330); the mean cylinder, -1.67 ± 1.00 D (P < .00); and the mean center K - maximum K, -4.92 ± 4.36 D (P < .05). The CDVA improved more than 2 lines; no eye lost any lines. Topographic indices improved in all eyes. Single ICRS implantation in eyes with moderate to severe keratoconus and inferiorly located cones was safe and effective. The development of a nomogram relying more on topographic data is suggested. No author has a financial or proprietary interest in any material or method mentioned.