Tono-Pen estimation of intraocular pressure through bandage contact lenses

The Tono-Pen was used to determine the reliability of intraocular pressure readings obtained through bandage contact lenses in 48 eyes of 24 healthy volunteers. The mean difference between readings obtained before lens insertion and readings obtained with the lens in place was 0.27 mm Hg and was not statistically significant (P greater than .2). The mean difference between readings obtained with the lens in place and readings obtained after lens removal was 0.85 mm Hg and was statistically significant (P less than .01). Ninety-five percent confidence intervals suggest that the true difference between mean Tono-Pen readings obtained with and without the lens in place ranges from -0.3 to +1.5 mm Hg. Our results suggest that the Tono-Pen is probably an effective way to estimate intraocular pressure through bandage contact lenses, with a probable true mean difference of less than 1.5 mm Hg and a standard deviation of about 2 mm Hg.