Intrastromal corneal ring segment implantation to correct astigmatism after penetrating keratoplasty

Abstract

Intrastromal corneal ring segments effectively reduced corneal cylinder in patients with astigmatism after PKP.

Management of Extreme Ametropia after Penetrating Keratoplasty: A Series of Surgical Procedures for High Myopia and Astigmatism

“…In some cases, anisometropia may develop, causing diplopia and blurred vision [5]. The management of these refractive problems is initially focused on conservative means – spectacle lenses and contact lenses – before introducing invasive procedures as surgical options [6]. Different methods, as already presented in the introduction, have been employed to correct refractive errors in patients after PKP.…”

“…Intrastromal corneal ring segment (ICRS) implantation (Ferrara rings) has been used in patients with positive visual outcomes after PKP, reducing the keratometric measures [13]. Recommendations vary in relation to time after PKP for ICRS implantation, with a waiting time of 1–2 years after corneal transplantation in order to achieve adequate tectonic, refractive, and immunogenic stability [6, 14].…”

“…Recommendations vary in relation to time after PKP for ICRS implantation, with a waiting time of 1–2 years after corneal transplantation in order to achieve adequate tectonic, refractive, and immunogenic stability [6, 14]. The implantation of ICRS after PKP has different results compared to corneas with keratoconus: in PKP corneas, 73% of the eyes were undercorrected and had a low concordance between the attempted refraction and the achieved refraction.…”

“…The implantation of ICRS after PKP has different results compared to corneas with keratoconus: in PKP corneas, 73% of the eyes were undercorrected and had a low concordance between the attempted refraction and the achieved refraction. This undercorrection can be related to PKP corneas being more rigid with normal thickness and elasticity compared to corneas of keratoconus that are thinner and more elastic [6]. The ICRS implantation can have several complications affecting the results and might not achieve the correction of the astigmatism; examples would be spontaneous suture rupture, immune reactions, and migration of ICRS [15].…”

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

“…The use of intrastromal corneal ring segments (ICRS) in keratoconus is an effective method of regularizing the corneal shape and improving vision. [1][2][3][4][5][6][7][8] Intacs SK (SK standing for severe keratoconus) (Additional Technology, Inc.) are poly(methyl methacrylate) short-segment ICRS with an elliptical profile that are usually placed at 6.0 mm. The manufacturer's nomogram recommends placing 2 segments (symmetric or asymmetric) to correct for myopia and astigmatism.…”