title: Optical coherence tomography to assess intrastromal corneal ring segment depth in keratoconic eyes.
abstract: OBJECTIVE
  To investigate intrastromal corneal ring segment depth with a high-speed corneal optical coherence tomography (OCT) system.
  
  
  METHODS
  Doheny Eye Institute, University of Southern California, Los Angeles, California, USA.
  
  
  METHODS
  A prospective observational case series comprised 4 eyes of 4 patients receiving Intacs intrastromal corneal ring segments (Addition Technology, Inc.) for keratoconus. Optical coherence tomography (OCT) was performed between 7 days and 43 days after implantation.
  
  
  RESULTS
  The slitlamp impression of intrastromal corneal ring segment implantation depth did not correlate well with OCT measurements (r(2) = 0.68). The fractional implantation depth was correlated with several surgical variables using a stepwise multivariate regression model, and 2 statistically significant correlations were found. The position of the distal portions of the ring segments was shallower than that of the portion closer to the insertion site (P = .003). Segments placed in the inferior cornea (P = .008) experienced more distal shallowing. Shallower depth was associated with greater fractional anterior stromal compression (P = .04).
  
  
  CONCLUSIONS
  Shallower placement of intrastromal corneal ring segments may result in more complications, such as epithelial-stromal breakdown and extrusion, because of the greater anterior stromal tensile strain. The distal and inferior portions of intrastromal corneal ring segments tended to be placed at a shallower depth. Optical coherence tomography provided precise measurement of ring segment depth and may help identify implants that pose a greater risk for depth-related complications.
authors.affiliation: Doheny Eye Institute and Department of Ophthalmology, University of Southern California, Los Angeles, California, USA.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Lai
authors.forename: Maolong
authors.initials: M
authors.lastname: Tang
authors.forename: Eduardo M M
authors.initials: EM
authors.lastname: Andrade
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Rahul N
authors.initials: RN
authors.lastname: Khurana
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Song
authors.forename: David
authors.initials: D
authors.lastname: Huang
mesh_terms: D000328:Adult; D003319:Corneal Stroma / Q000473:pathology* / Q000601:surgery*; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D041623:Tomography, Optical Coherence / Q000379:methods*