title: Intraocular pressure and photorefractive keratectomy: a comparison of three different tonometers.
abstract: OBJECTIVE
  To evaluate the intraocular pressure (IOP) with three different instruments, Goldmann applanation tonometer (GAT), noncontact tonometer, and Tono-Pen after photorefractive keratectomy (PRK) for myopia.
  
  
  METHODS
  A prospective case series study to evaluate preoperative and postoperative IOP measurements of 149 eyes at 12 months. We performed GAT, noncontact tonometry, Tono-Pen central, and Tono-Pen temporal periphery measurements. We also performed measurements of the central corneal thickness (CCT) by ultrasonic pachymetry and keratometry. Pre-operative IOP reading served as control for all studies.
  
  
  RESULTS
  After PRK, IOP reading was significantly reduced in the treated eyes when compared with the control measurements (11.87+/-1.73 vs. 13.37+/-1.52 mm Hg, p<0.0001 with GAT; 12.07+/-1.6 vs. 13.51+/-1.59 mm Hg, p<0.0001 with noncontact tonometer; 12.18+/-1.6 vs. 13.48+/-1.55 mm Hg, p<0.0001 with Tono-Pen central; 13.48+/-1.65 vs. 13.71+/-1.56 Hg, p<0.0104 with Tono-Pen temporal periphery). There was also a significant correlation between IOP reading changes measured by GAT, noncontact tonometer, Tono-Pen central, and change of CCT and between reduction of IOP reading and keratometry (r2>0.39, p<0.0001 for each). The correlation between IOP reading change by Tono-Pen temporal periphery and CCT was also significant but r2 value was only 0.034. Tono-Pen temporal periphery postoperative IOP measurements had the best correlation with preoperative GAT IOP (r2 = 0.57, p<0.0001).
  
  
  CONCLUSIONS
  PRK reduced IOP reading as measured by GAT, noncontact tonometer, and Tono-Pen central; less so when measured by Tono-Pen temporal periphery. Early detection of glaucoma and IOP follow-up in glaucoma patients may be done best by peripheral Tono-Pen measurements over the nonablated cornea.
authors.affiliation: Department of Ophthalmology, Haemek Medical Center, Afula, Israel.
authors.forename: H J
authors.initials: HJ
authors.lastname: Garzozi
authors.forename: H S
authors.initials: HS
authors.lastname: Chung
authors.forename: Y
authors.initials: Y
authors.lastname: Lang
authors.forename: L
authors.initials: L
authors.lastname: Kagemann
authors.forename: A
authors.initials: A
authors.lastname: Harris
mesh_terms: D000328:Adult; D003315:Cornea / Q000000981:diagnostic imaging / Q000601:surgery; D005260:Female; D005901:Glaucoma / Q000175:diagnosis; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D054018:Lasers, Excimer; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery; D018903:Photorefractive Keratectomy; D011182:Postoperative Care / Q000379:methods; D011300:Preoperative Care / Q000379:methods; D011379:Prognosis; D011446:Prospective Studies; D015203:Reproducibility of Results; D014065:Tonometry, Ocular / Q000295:instrumentation*; D014463:Ultrasonography