Femtosecond laser intracorneal ring segment implantation based on a nomogram modification in type 1 and type 2 ectasia

Abstract

Aims The aim of the study was to evaluate the refractive, topometric and aberrometric changes in corneas with keratoconus treated with femtosecond laser intracorneal ring segment (ICRS) implantation following a proposed modified nomogram. Settings and design This is a retrospective, consecutive case series. Materials and methods ICRS implantation using the new proposed nomogram was performed in 10 eyes of seven patients with type 1 and type 2 keratoconus. Corneal tunnels were created using femtosecond laser, and KeraRings were inserted in all eyes. All cases were followed up every 3 months for 6 months using the Pentacam Phoenix system. Statistical analysis All analyses were performed with SPSS for windows 2007. Results None of our patients developed complications related to ring placement, such as migration, extrusion or infection. In this limited case series an improvement was seen in uncorrected visual acuity (P 0≤ 0.05), best spectacle corrected visual acuity (P ≤ 0.001) and refraction at 6 months (P < 0.001). Keratometric readings improved (P < 0.001), with flattening of the cornea. Corneal aberrations showed significant reduction when analysed by Zernike (P < 0.001) and Fourier analysis ( P ≤ 0.001). Corneal asphericity (Q value) also showed improvement (P < 0.05). Conclusion Femtolaser ICRS implantation using the proposed modified nomogram showed promising results in improving refraction, visual acuity, corneal topography and aberrations in patients with keratoconus.

Keywords

• Corneal ectasia
• femtosecond-laser assisted intracorneal ring segment
• intracorneal rings
• keraring nomogram
• keratoconus subtypes