Characteristics of Astigmatism after MyoRing Implantation

Abstract Considering the rising number of MyoRing implantation procedures in keratoconic corneas and the refractive outcomes associated with this treatment modality, this study aimed to evaluate and compare the magnitude and axis orientation of total and corneal astigmatism between before and after MyoRing implantation in ۳۴ eyes of ۲۸ patients with keratoconus (KCN) (mean age: ۲۹.۴۱ ± ۷.۰ years). The inclusion criterion was a reliable diagnosis of clinical KCN based on corneal biomicroscopic and tomographic findings. The mean total astigmatism of ocular refraction decreased significantly from -۴.۲۷ ± ۳.۱۵ D (before MyoRing implantation) to -۲.۱۸ ± ۱.۶۳ D (after MyoRing implantation) (P < ۰.۰۰۱). The mean astigmatism in the anterior and posterior surface of the cornea decreased significantly by ۱.۱۶ D (P = ۰.۰۰۱) and ۰.۲۴ D (P = ۰.۰۰۹), respectively, after MyoRing implantation. Before MyoRing implantation, the axis orientation of total ocular astigmatism for with-the-rule, oblique, and against-the-rule astigmatism was ۲۱%, ۴۲%, and ۳۷%, respectively; at ۶ months after MyoRing implantation, it was ۱۸%, ۲۴%, and ۵۸%, respectively. Before MyoRing implantation, the axis orientation for with-the-rule, against-the-rule, and oblique astigmatism of the anterior surface of the cornea was ۵۹%, ۲۴%, and ۱۷%, respectively; at ۶ months after MyoRing implantation, it was ۵۲%, ۲۴%, and ۲۴%, respectively. Before MyoRing implantation, the axis orientation of with-the-rule, oblique, and against-the-rule astigmatism of the posterior surface of the cornea was ۶۸%, ۲۹%, and ۳%, respectively; at ۶ months after MyoRing implantation, it was ۶۷%, ۱۲%, and ۱۲%, respectively. MyoRing implantation significantly decreased the amount of total, anterior, and posterior corneal astigmatism.