Intrastromal corneal ring segment implantation to correct astigmatism after penetrating keratoplasty

PurposeTo evaluate the clinical outcomes of implantation of Ferrara intrastromal corneal ring segments (ICRS) in patients with astigmatism after penetrating keratoplasty (PKP).SettingPrivate clinic, Belo Horizonte, Brazil.DesignRetrospective consecutive case series.MethodsChart records of post-PKP patients who had ICRS implantation from May 2005 to September 2009 were retrospectively reviewed. The following parameters were studied: corrected distance visual acuity (CDVA), keratometry (K) values, spherical equivalent (SE), spherical refractive error, corneal topographic astigmatism, minimum K, and maximum K.ResultsThe study evaluated 59 eyes (54 patients). The mean CDVA (logMAR) improved from 0.45 ± 0.17 (SD) (range 0.18 to 1.00) to 0.30 ± 0.17 (range 0.00 to 1.00). The mean SE was −6.34 ± 3.40 diopters (D) (range 0.37 to −16.50 D) preoperatively and −2.66 ± 2.52 D (range 0.87 to −10.50 D) postoperatively. The mean spherical refractive error decreased from −7.10 ± 3.07 D (range 2.15 to 16.68 D) preoperatively to −3.46 ± 2.05 D (range 0.88 to 10.79 D) postoperatively. No patient lost visual acuity. The mean corneal topographic astigmatism decreased from 3.37 ± 1.51 D preoperatively to 1.69 ± 1.04 D postoperatively. The mean maximum K value decreased from 48.09 ± 2.56 D to 44.17 ± 2.67 D and the mean minimum K value, from 44.90 ± 2.54 D to 42.46 ± 2.63 D. All changes were statistically significant (P<.0001).ConclusionIntrastromal corneal ring segments effectively reduced corneal cylinder in patients with astigmatism after PKP.Financial DisclosureDrs. Ferrara and Merayo-Lloves have proprietary interest in the Ferrara ring. Drs. Coscarelli, Torquetti, and Alfonso have no financial or proprietary interest in any material or method mentioned.