Effect of soft contact lenses on the measurements of intraocular pressure with non-contact pneumotonometry.
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.
Schollmayer
Petra
P
University Eye Clinic, Medical Centre Ljubljana, Slovenia. petraschollmayer@hotmail.com
Hawlina
Marko
M
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*