Femtolaser-Assisted Implantation of 2 ICRS Models or a Full-Ring Implant for Proposed Subtypes of Type III Ectasia
Purpose
To compare the refractive, topometric and aberrometric changes in corneas with type III ectasia treated by femtolaser implantation of either two Kera SI5 intracorneal ring segments (ICRS) or a Myoring.
Methods
Retrospective, consecutive case series. Intracorneal ring segment implantation was performed in 18 eyes of 13 patients with Type III ectasia. We divided the patients with type III ectasia into two groups according to their topography. The first group included the patients with a symmetrical figure of eight cone while the second group included those with asymmetric cones with more inferior steepening or a "pot belly". In the first group (6 eyes) we implanted a Myoring while in the second group (12 eyes) we implanted two 160 arc length SI5 Kera ICRS. Corneal tunnels were created by femtosecond laser. All cases were followed up for 6 months.
Results
At 6 months there was an improvement in UCVA (P≤0.05), BCVA (P<0.001), and Refraction (P<0.001). Keratometric readings changed (P<0.001), with flattening of the cornea. Corneal aberrations showed significant reduction when analyzed by Zenike (P<0.001), and Fourier analysis (P<0.001). Corneal asphericity (Q value) also showed improvement (P≤0.05).
Conclusion
Although this is a limited case series, subtyping type III keratoconus and choosing whether to implant a Myoring or two kissing 160 arc length Keraring ICRS shows promising results in terms postoperative visual acuity, refraction, corneal topography, Q value, corneal aberrations and patient satisfaction.