title: Applanation tonometry in silicone hydrogel contact lens wearers.
abstract: BACKGROUND
  Previous studies have investigated intraocular pressure (IOP) measurements through conventional soft (hydrogel) therapeutic contact lenses, and have found that an accurate IOP can be recorded in normal eyes, and in eyes with abnormal anterior segments. The IOP measurement through soft contact lenses may be affected by the water content and centre thickness of the lens. Silicone hydrogel contact lenses are now being used as therapeutic contact lenses due to their high oxygen permeability. The purpose of this study is to investigate if IOP can be accurately measured in a subject wearing a silicone hydrogel contact lens.
  
  
  METHODS
  In a cohort study, the IOP was measured with a Goldmann applanation tonometer without a contact lens and then repeated with a hydrogel contact lens in situ.
  
  
  RESULTS
  The IOP of 20 eyes of 10 volunteers with no ocular pathology was measured. The mean difference (+/-S.D.) found between IOP measurement with (mean 15.55+/-1.70 mmHg) and without (mean 16.05+/-1.90 mmHg) contact lens was found to be -0.5+/-0.89 mmHg. Statistical analysis was performed which revealed a correlation coefficient of 0.89. No significant statistical difference was found between the two groups with paired t-test (p=0.19).
  
  
  CONCLUSIONS
  Accurate measurement of IOP by applanation tonometry can be achieved through a silicone hydrogel contact lens.
authors: Essex County Hospital, Colchester, United Kingdom. richardallen_@btopenworld.com
authors: R J
authors: RJ
authors: Allen
authors: A
authors: A
authors: Dev Borman
authors: G M
authors: GM
authors: Saleh
mesh_terms: D000328:Adult; D015331:Cohort Studies; D003263:Contact Lenses, Hydrophilic; D005260:Female; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012828:Silicones; D014065:Tonometry, Ocular / Q000379:methods* / Q000592:standards
chemical_list: D012828:Silicones; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate