Accuracy of tonometry over soft contact lenses using Tono-Pen XL

Purpose: To evaluate the accuracy of intraocular pressure (lOP) measurements taken through a commonly used soft contact lens using Tono-Pen. Methods: Measure the lOP of fifty eyes using Tono-Pen. A myopic soft contact lens (Biomedics 38's) was placed on the eyes and lOP measurements were taken through the soft contact lenses. The readings obtained for the contact lens were compared to the baseline readings taken without a lens in place in order to assess the effect that the contact lens had on the accuracy of lOP measurements. Results: The contact lens permitted accura1e lOP measurements. The mean lOP ( ± SD) taken through the soft contacts was 11.87 ±2.58 mm Hg. The mean baseline lOP was 12.25 ± 2.97 mm Hg, The difference between the mean was fpund to be insignificant with a p-value =.12. Conclusion: Tono-pen proved to be reliable in recording accurate lOP measurements through a myopic contact lens