title: Intraocular pressure measurement in patients with instrastromal corneal ring segments.
abstract: OBJECTIVE
  To study the measurement of intraocular pressure after implantation of Intacs (ICRS) intrastromal corneal ring segment, a device that is positioned circumferentially in the peripheral corneal stroma to correct myopia. The device changes the corneal curvature by shortening arc length. Since the ring segments are made of polymethylmethacrylate, this may cause localized changes in corneal elasticity so intraocular pressure measurement may be affected.
  
  
  METHODS
  We measured the intraocular pressure of 12 eyes in which the ICRS had been in place longer than 6 months. We used Goldmann applanation and Tono-Pen tonometers over the central corneal and the paracentral corneal areas. We also measured the intraocular pressure with the Tono-Pen applanated directly over the intrastromal corneal ring segments.
  
  
  RESULTS
  The resulting intraocular pressure measurements were similar for the Tono-Pen tonometer readings over the central cornea, paracentral cornea, and the Goldmann applanation tonometer readings over the central cornea (P < .01). Our measurements using the Goldmann applanation tonometer on the paracentral corneal area showed artificially elevated intraocular pressure in the 40 to 60 mmHg range. We were not able to obtain consistent results when we measured the intraocular pressure using the Tono-Pen on the corneal area directly overlying the intrastromal corneal ring segment implants.
  
  
  CONCLUSIONS
  Consistent intraocular pressure measurements on eyes with the ICRS can be obtained with the Goldmann applanation tonometer over the central corneal area or with the Tono-Pen tonometer over the central or paracentral corneal areas.
authors.affiliation: Shiley Eye Center, University of California at San Diego, La Jolla 92093, USA.
authors.forename: D B
authors.initials: DB
authors.lastname: Tran
authors.forename: D
authors.initials: D
authors.lastname: Zadok
authors.forename: M
authors.initials: M
authors.lastname: Carpenter
authors.forename: T S
authors.initials: TS
authors.lastname: Korn
authors.forename: M
authors.initials: M
authors.lastname: Twa
authors.forename: D J
authors.initials: DJ
authors.lastname: Schanzlin
authors.forename: T S
authors.initials: TS
authors.lastname: Kom
mesh_terms: D003319:Corneal Stroma / Q000601:surgery*; D006801:Humans; D007429:Intraocular Pressure; D009216:Myopia / Q000601:surgery*; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D014065:Tonometry, Ocular / Q000379:methods