Corneal aberrometric and refractive performance of 2 intrastromal corneal ring segment models in early and moderate ectatic disease

Abstract

Purpose: To evaluate and compare visual, refractive, and corneal aberrometric outcomes after implantation of 2 types of intrastromal corneal ring segments (ICRS) in eyes with early to moderate ectatic disease. Settings: Vissum Corporation-Instituto Oftalmológico de Alicante, Alicante, Spain. Methods: This retrospective analysis comprised consecutive eyes with grade I or grade II corneal ectasia (keratoconus, pellucid marginal degeneration, ectasia after laser in situ keratomileusis) that had Intacs (Group I) or KeraRings (Group K) ICRS implantation using femtosecond technology. Visual, refractive, and corneal aberrometric outcomes were analyzed and compared between groups over a 6-month follow-up. Results: Group I had 17 eyes and Group K, 20 eyes. One month postoperatively, there was a statistically significant reduction in sphere in both groups (P≤.02). At 6 months, there was a statistically significant reduction in manifest cylinder in Group K that was consistent with the significant reduction in corneal astigmatic aberration (both P = .04). The uncorrected distance visual acuity increased significantly in Group K (P = .04) but not in Group I; 41.18% of eyes in Group I and 52.94% in Group K gained 1 or more lines of corrected distance visual acuity. Both groups had significant corneal flattening (P≤.02). At 1 month, the mean primary spherical aberration was −0.17 μm ± 0.52 (SD) in Group I and 0.40 ± 0.35 μm in Group K; the difference was statistically significant (P<.01). Conclusion: Astigmatism correction in early to moderate ectatic corneas was more limited with the Intacs ICRS, which induced negative primary spherical aberration in the initial postoperative period.