title: Refractive and visual outcomes after Intacs vs ferrara intrastromal corneal ring segment implantation for keratoconus: a comparative study.
abstract: OBJECTIVE
  To evaluate the refractive, topographic, optical, visual acuity, and quality outcomes of two types of intrastromal corneal ring segments (ICRS) in the treatment of keratoconus.
  
  
  METHODS
  In this retrospective study, 16 eyes that had been implanted with Intacs ICRS (Addition Technology Inc) (Intacs group) and 17 eyes implanted with Ferrara ICRS (Ferrara Ophthalmics Ltda) (Ferrara group) were evaluated. Pre- and postoperative examinations included uncorrected and corrected distance visual acuities (UDVA and CDVA, respectively), manifest refraction, slit-lamp examination, topography, and ocular wavefront analysis. Contrast sensitivity measurements under photopic, scotopic, and scotopic with glare conditions were performed 1 year postoperatively.
  
  
  RESULTS
  One year postoperatively, a significant decrease was noted in spherical equivalent refractive error of 3.76 ± 0.39 diopters (D) and 3.42 ± 0.88 D and keratometry of 3.43 ± 0.24 D and 3.28 ± 0.78 D in the Intacs and Ferrara groups, respectively; and increase in mean UDVA and CDVA in Snellen lines of 0.18 ± 0.04 and 0.21 ± 0.05, respectively, in the Intacs group and 0.21 ± 0.09 and 0.26 ± 0.08, respectively, in the Ferrara group (P<.01 for all). The postoperative increase in UDVA and CDVA and decrease in keratometry readings were not significantly different between groups (P>.05 for all). Mean higher order aberrations decreased in the Intacs group and increased in the Ferrara group (P>.05 for both). Postoperatively, a significant decrease was noted in scotopic contrast sensitivity when glare was introduced in the Ferrara group, which was positively correlated with pupil diameter (r(15)=0.50, P=.04).
  
  
  CONCLUSIONS
  Both ICRS types provided comparable refractive, topographic, and optical quality outcomes. Eyes with Ferrara ICRS experienced greater decrease in scotopic contrast sensitivity under glare, which was significantly correlated with pupil diameter.
authors.affiliation: Beyoglu Eye Research and Training Hospital, Istanbul, Turkey.
authors.forename: Vedat
authors.initials: V
authors.lastname: Kaya
authors.forename: Canan Asli
authors.initials: CA
authors.lastname: Utine
authors.forename: Sezen Harmanci
authors.initials: SH
authors.lastname: Karakus
authors.forename: Isilay
authors.initials: I
authors.lastname: Kavadarli
authors.forename: Omer Faruk
authors.initials: OF
authors.lastname: Yilmaz
mesh_terms: D001672:Biocompatible Materials; D015350:Contrast Sensitivity / Q000502:physiology; D003319:Corneal Stroma / Q000601:surgery*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000601:surgery*; D008297:Male; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D012029:Refraction, Ocular / Q000502:physiology*; D012189:Retrospective Studies; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult
chemical_list: D001672:Biocompatible Materials