360-Degree Intrastromal Corneal Ring for Advanced Keratoconus
Narrative Responses:
Purpose
To evaluate visual outcomes, tomographic and topographic parameters after implantation of 360 degrees intrastromal corneal ring for advance keratoconus using femtosecond laser.
Methods
Prospective study that included 16 eyes of 12 patients with diagnosis of keratoconus stage III and IV (according to Amsler-Krumeich classification) that underwent a 360 degrees intrastromal corneal ring (MyoRing, Dioptex GmbH) implantation by a pocket created by the femtosecond laser (Z6 - Ziemer) between July 2012 and march 2013. The pocket had 9 mm diameter, 4.5 mm aperture, and the deep was calculated 100 um less than the pachymetry at thinnest point of the cornea. Pre and postoperative (3 months) uncorrected and best-corrected visual acuity (UCVA, BCVA respectively), keratometry, pachymetry and elevation maps were evaluated and compared.
Results
Mean uncorrected visual acuity was 1.29 LogMAR preoperatively and 0.51 LogMAR at 3 months (P <0.001). Mean reduction of the maximum keratometry was 4.2 Diopters (D) at 3 months postoperative (p= 0.04). Mean reduction in the spherical equivalent was 4.54D (p< 0.001), and mean reduction in the cylinder was 1.82D (p= 0.003).
Conclusion
360 degrees intrastromal corneal ring by femtosecond laser pocket is safe and efficacious for correct the refractive error in advanced keratoconus.