title: Clinical outcomes after complete ring implantation in corneal ectasia using the femtosecond technology: a pilot study.
abstract: OBJECTIVE
  To evaluate the clinical outcomes after implantation of the MyoRing (DIOPTEX GmBH, Linz, Austria) by means of femtosecond laser technology in eyes with corneal ectasia.
  
  
  METHODS
  Retrospective, consecutive, nonrandomized, case series.
  
  
  METHODS
  A total of 12 eyes of 11 patients with ages ranging from 17 to 50 years were included. All cases were diagnosed with corneal ectasia according to the standard criteria: 1 case of post-LASIK ectasia and 11 cases of keratoconus. All cases presented with reduced best spectacle-corrected visual acuity, contact lens intolerance or discomfort, and central corneal thickness of more than 350 μm.
  
  
  METHODS
  MyoRing inserts of 280 μm in thickness and 5 mm in diameter were implanted in all cases into an intrastromal corneal pocket created by means of femtosecond technology. Visual, refractive, corneal topography, and pachymetric changes were evaluated during a 6-month follow-up. In addition, corneal biomechanical changes were evaluated by means of the Ocular Response Analyzer (Reichert, Buffalo, NY).
  
  
  METHODS
  Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction, keratometry, corneal asphericity, corneal higher-order aberrations, pachymetry, corneal hysteresis (CH), and corneal resistance factor (CRF).
  
  
  RESULTS
  A significant improvement in UDVA was observed 1 week after surgery (P=0.001), which was consistent with the significant reduction in sphere (P=0.002) and cylinder (P=0.004). No significant changes were detected in these parameters afterward (P ≥ 0.263). Furthermore, a significant corneal flattening of a mean value of 8.03 diopters (D) was found (P=0.005). This keratometric change was correlated with the magnitude of corneal coma-like aberrations (r=0.830, P=0.003) and the CRF (r=-0.782, P=0.008). In regard to aberrometry, a statistically significant increase in primary spherical aberration was found 1 month after surgery (P=0.001). In addition, a significant reduction in higher-order corneal aberrations was found 3 to 6 months after surgery (P=0.027). Significant corneal thickening was also observed postoperatively in the central, nasal, and temporal areas (P ≤ 0.013). No statistically significant changes were detected (P ≥ 0.176) in corneal biomechanics. Explantation was performed in a very advanced keratoconus because of the extremely poor visual outcome.
  
  
  CONCLUSIONS
  MyoRing implantation using femtosecond technology in keratoconus allows successful corneal modeling, although the use of large diameters is advisable.
authors: Vissum/Instituto Oftalmológico de Alicante, Spain. jlalio@vissum.com
authors: Jorge L
authors: JL
authors: Alio
authors: David P
authors: DP
authors: Piñero
authors: Albert
authors: A
authors: Daxer
mesh_terms: D000293:Adolescent; D000328:Adult; D002921:Cicatrix / Q000601:surgery*; D003315:Cornea / Q000378:metabolism / Q000473:pathology; D003316:Corneal Diseases / Q000175:diagnosis / Q000601:surgery*; D019781:Corneal Topography; D057108:Corneal Wavefront Aberration; D004867:Equipment Design; D005139:Eyeglasses; D005500:Follow-Up Studies; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis / Q000601:surgery*; D053685:Laser Therapy; D008875:Middle Aged; D010865:Pilot Projects; D019736:Prostheses and Implants; D019919:Prosthesis Implantation / Q000379:methods*; D012029:Refraction, Ocular; D016896:Treatment Outcome; D014792:Visual Acuity; D055815:Young Adult