title: Outcome of intrastromal corneal ring segment relative to depth of insertion evaluated with scheimpflug image.
abstract: OBJECTIVE
  To report the results of intrastromal corneal ring segment (KeraRing; Mediphcose, Belo Horizonte, Brazil) implantation relative to depth of insertion in keratoconic patients.
  
  
  METHODS
  In this retrospective, observational study, we evaluated 29 eyes of 27 patients with keratoconus who underwent implantation of KeraRing SI-5 with mechanical tunnel creation. In the mean follow-up of 8.8 months, all eyes underwent scheimpfluge image of pentacam (Oculus, Germany) to determine insertion depth. Based on the measured implantation depth, cases were categorized into: 40-59% thickness group, 60-79% thickness group, and ≥80% thickness group. Visual, refractive, and shape outcomes were evaluated relative to implantation depth.
  
  
  RESULTS
  The mean insertion depth was 61.7%.We had 41.4% of cases were in the 40-59% thickness group, 51.7% in the 60-79% group, and 6.9% in the >80% group. Results were similar in 40-59% and 60-79% thickness groups: uncorrected visual acuity (UCVA) and best spectacle corrected VA (BSCVA) improved 3 and 2 lines, respectively, maximum keratometry (Kmax) decreased 2.6 D, refractive cylinder improved 2.04 D, and Q value 8 mm anterior changed by 0.35. In the ≥80% thickness group, UCVA and BSCVA improved less than 1 lines, Kmax change was less than 0.5 D, and RC decreased less than 0.25 D.
  
  
  CONCLUSIONS
  Implantation of KeraRing with mechanical tunnel creation in 40-80% of stromal thickness despite the variable insertion depth is effective.
authors.affiliation: Ophthalmology Department, Nikookari Eye Hospital, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Afshin Lotfi
authors.initials: AL
authors.lastname: Sadigh
authors.affiliation: Ophthalmology Department, Nikookari Eye Hospital, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Taha Ahmad
authors.initials: TA
authors.lastname: Aali
authors.affiliation: Ophthalmology Department, Nikookari Eye Hospital, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Sadeghi
keywords: KeraRing; Keratoconus; Pentacam; Scheimpflug