Clinical evaluation of two types of intracorneal ring segments (ICRS) for keratoconus.

Purpose: To compare the outcome measures following implantation of two types of ICRS.

Methods: Forty-four eyes of keratoconic patients (aged 18-50 years) were randomly assigned to femtosecond laser-assisted Keraring ICRS (Group A) or MyoRing (Group B) implantation. Uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refraction, keratometry (K), and aberrations were compared preoperatively, at 3 and 6 months postoperatively. A survey was conducted to assess patient's satisfaction, 6 months postoperatively.

Results: In Groups A (n = 26) and B (n = 18), UDVA was increased (P < 0.05), but CDVA increased only in Group A (P < 0.05) 6 months postoperatively. The mean K was reduced by 4.55 D (P < 0.0001) in Group A and 6.51 D (P < 0.001) in Group B. Six months postoperatively, the mean refraction spherical equivalent (MRSE) decreased by 2.90 and 3.60 D in Groups A and B, respectively (P < 0.0001). Between groups, coma was more reduced (P = 0.035) in Group B than A, 6 months postoperatively. On motivation for surgery, 88.9% of patients' ranked "desire to improve unaided vision" and "relief from glasses" (77%) topmost. Seventy-seven (77%) of Group A and 89% of Group B patients were satisfied with their unaided vision at the final visit, after 6 months.

Conclusions: KeraRing (A) and MyoRing (B) corneal implants both performed well in improving vision and stabilising the cornea. Implantation of the MyoRing caused greater reduction in coma and better patient satisfaction, but CDVA improved only in the Keraring group, at the final visit.