title: Validity of Tono-pachymetry for Measuring Corrected Intraocular Pressure in Non-surgical and Post-photorefractive Keratectomy Eyes.
abstract: OBJECTIVE
  To assess the validity of central corneal thickness (CCT) and corrected intraocular pressure (IOP) values obtained by tono-pachymetry in non-surgical and post-photorefractive keratectomy (PRK) eyes.
  
  
  METHODS
  For the study, 108 young healthy participants and 108 patients who had PRK were enrolled. Measurements were randomly performed by tono-pachymetry, ultrasonic (US) pachymetry, and Goldmann applanation tonometry (GAT). CCT measurement by tono-pachymetry was compared to that of US pachymetry. The corrected IOP value obtained by tono-pachymetry was compared to that obtained by US pachymetry and GAT. The corrected IOP from US pachymetry and GAT was calculated using the identical compensation formula built into the tono-pachymetry. Bland-Altman plot and pairedt-test were conducted to evaluate the between-method agreements.
  
  
  RESULTS
  The mean CCT measurement using tono-pachymetry was significantly greater by 7.3 µm in non-surgical eyes (p< 0.001) and 17.8 µm in post-PRK eyes (p< 0.001) compared with US pachymetry. Differences were significant in both Bland-Altman plotand pairedt-test. The mean difference of corrected IOP values obtained by tono-pachymetry and calculated from measurements by US pachymetry and GAT was 0.33 ± 0.87 mmHg in non-surgical eyes and 0.57 ± 1.08 mmHg in post-PRK eyes. The differences in the Bland-Altman plot were not significant.
  
  
  CONCLUSIONS
  The CCT measurement determined using tono-pachymetrywas significantly thicker than that of US pachymetry. The difference in CCT was greater in post-PRK eyes than in non-surgical eyes. However, the corrected IOP value obtained by tono-pachymetry showed reasonable agreement with that calculated from US pachymetry and GAT measurements.
authors.affiliation: Department of Ophthalmology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: In Kyun
authors.initials: IK
authors.lastname: Hahn
authors.affiliation: Department of Ophthalmology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Jae Yong
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Department of Ophthalmology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Myoung Joon
authors.initials: MJ
authors.lastname: Kim
authors.affiliation: Department of Ophthalmology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Hungwon
authors.initials: H
authors.lastname: Tchah
authors.affiliation: Department of Ophthalmology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.; Department of Ophthalmology, Aerospace Medical Center, Republic of Korea Air Force, Cheongju, Korea.
authors.forename: Chan Hee
authors.initials: CH
authors.lastname: Moon
mesh_terms: D000328:Adult; D003315:Cornea / Q000000981:diagnostic imaging / Q000601:surgery*; D063171:Corneal Pachymetry / Q000379:methods*; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D018903:Photorefractive Keratectomy / Q000379:methods*; D015203:Reproducibility of Results; D014065:Tonometry, Ocular / Q000379:methods*; D055815:Young Adult
keywords: Corneal pachymetry; Intraocular pressure; Photorefractive keratectomy