title: Effect of soft contact lenses on the measurements of intraocular pressure with non-contact pneumotonometry.
abstract: OBJECTIVE
  To evaluate the effect of soft contact lenses with different lens power on the measured value of the intraocular pressure with non-contact pneumotonometry.
  
  
  METHODS
  120 eyes (80 healthy volunteers: 50 women, 30 men, aged 22 to 61 years) were included in this study. Intraocular pressure was measured with a pneumotonometer Canon X-10 before and after insertion of the Ciba Vision Focus Night&Day soft contact lens. We used contact lenses with different lens power of + 0.25 D, + 1.00 D, + 4.00 D, - 1.00 D, and - 4.00 D. The averages of three measurements were taken as representative IOP values that were statistically evaluated.
  
  
  RESULTS
  IOP measured over myopic lenses of - 1.00 and - 4.00 D showed lower values within the mean range of 1 mm Hg. The difference between the measurements over the myopic lenses was mostly smaller than +/- 2 mm Hg (78% when using - 1.00 D and 90% when using - 4.00 D contact lens). All the differences using + 0.25 D contact lens were smaller than +/- 2 mm Hg. The difference was considerably higher in measurements over + 1.00 and + 4.00 hyperopic contact lenses and showed strong increase with the lens power.
  
  
  CONCLUSIONS
  In our study we showed that intraocular pressure can be reliably measured with non-contact pneumotonometry over myopic lenses or hypermetropic lenses with small lens power. This suggests that non-contact pneumotonometry is a useful method in patients wearing therapeutic contact lenses and contact lens wearers who, when measuring the eye pressure, would not need to remove the contact lenses before the examination.
authors.affiliation: University Eye Clinic, Medical Centre Ljubljana, Slovenia. petraschollmayer@hotmail.com
authors.forename: Petra
authors.initials: P
authors.lastname: Schollmayer
authors.forename: Marko
authors.initials: M
authors.lastname: Hawlina
mesh_terms: D000328:Adult; D003263:Contact Lenses, Hydrophilic / Q000009:adverse effects; D005260:Female; D006801:Humans; D006956:Hyperopia / Q000503:physiopathology; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology; D055095:Optics and Photonics; D012029:Refraction, Ocular / Q000502:physiology; D015203:Reproducibility of Results; D014065:Tonometry, Ocular / Q000295:instrumentation / Q000706:statistics & numerical data*