Vertical versus oblique implantation of intrastromal corneal ring segments for keratoconus

PurposeTo determine the effect on postoperative outcomes of different sites for intrastromal corneal ring segment (ICRS) implantation in keratoconic eyes.SettingEye Research Center of Mashhad University of Medical Sciences, Khatam-al-Anbia Eye Hospital, Mashhad, Iran.DesignCase series study.MethodsAfter a detailed ophthalmologic examination, pairs of 160-degree Ferrara ICRS were implanted in eyes with keratoconus. Patients were categorized into 2 groups depending on the axis of ICRS implantation as follows: vertical implantation, in which the axis of the radial incision was between 70 degrees and 110 degrees, and oblique implantation, in which the axis was outside the vertical range. An independent-samples t test was used to compare the postoperative refractive and visual outcomes in the 2 groups.ResultsThis series included 48 eyes of 48 patients (28 men, 20 women) with a mean age of 26.65 years ± 6.8 (SD). The vertical implantation group comprised 23 patients and the oblique implantation group, 25 patients. There was no statistically significant difference in any preoperative parameter between the groups. The mean postoperative corrected distance visual acuity and astigmatism reduction were significantly better in the vertical group than in the oblique group (P<.05).ConclusionAlthough the improvements in refractive outcomes and visual acuity were significant in eyes with vertical or oblique astigmatism, simulated keratometry showed that patients with a vertical steep axis had more favorable results than those with an oblique steep axis.Financial DisclosureNeither author has a financial or proprietary interest in any material or method mentioned.