title: The accuracy of Goldmann applanation tonometry over silicone hydrogel contact lenses in patients with glaucoma.
abstract: OBJECTIVE
  To investigate the accuracy of measuring intraocular pressure over a silicone hydrogel contact lens using Goldmann applanation tonometry in eyes with glaucoma.
  
  
  METHODS
  This was a prospective, randomized study and enrolled 28 patients (28 right eyes) with primary open angle glaucoma. Intraocular pressure was taken with and without a silicone hydrogel contact lens (-0.50 D), in situ (using Goldmann applanation tonometry), in a randomized order of measurements. Statistical analysis was performed using paired t-test and Bland-Altman plot.
  
  
  RESULTS
  The mean difference (± standard deviation) found between intraocular pressure measurement without (mean 16.7 ± 3.2 mmHg) and with (mean 17.3 ± 3.0 mmHg) contact lens was found to be -0.57 ± 2.3 mmHg (95% confidence interval, -1.5 to 0.3). No significant statistical difference was found between the two groups with paired t-test (p=0.19). The Bland Altman plot showed some evidence of increasing variability of differences between two measures of intraocular pressure, with increasing intraocular pressure. The 95% limits of agreement of the Bland Altman plot were unacceptably large (-5 mmHg to 3.9 mmHg).
  
  
  CONCLUSIONS
  Agreement between Goldmann applanation tonometry with and without contact lenses seems to be poor in patients with glaucoma, especially for high intraocular pressure.
authors.affiliation: Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; Federal Hospital of Bonsucesso, Rio de Janeiro, Brazil.
authors.forename: Beatriz A F
authors.initials: BA
authors.lastname: Gomes
authors.affiliation: Federal Hospital of Bonsucesso, Rio de Janeiro, Brazil.
authors.forename: Paulo
authors.initials: P
authors.lastname: Turiel
authors.affiliation: Federal Hospital of Bonsucesso, Rio de Janeiro, Brazil.
authors.forename: Rachel S
authors.initials: RS
authors.lastname: Cavalcanti
authors.affiliation: Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Haroldo V
authors.initials: HV
authors.lastname: Moraes
authors.affiliation: Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; University of São Paulo, São Paulo, Brazil. Electronic address: marconysanthiago@hotmail.com.
authors.forename: Marcony R
authors.initials: MR
authors.lastname: Santhiago
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D003263:Contact Lenses, Hydrophilic; D005260:Female; D005902:Glaucoma, Open-Angle / Q000175:diagnosis* / Q000534:rehabilitation*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014065:Tonometry, Ocular / Q000379:methods*; D016896:Treatment Outcome
keywords: Contact lens; Glaucoma; Intraocular pressure; Tonometry