Intraocular pressure readings obtained through soft contact lenses using four types of tonometer

Joji Takenaka,¹ Eriko Kunihara,¹ Ulfah Rimayanti,² Junko Tanaka,³ Makoto Kaneko,⁴ Yoshiaki Kiuchi<sup>1

1</sup>Department of Ophthalmology and Visual Science, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan; ²Faculty of Medicine and Health Sciences, UIN Alauddin Makassar, South Sulawesi, Indonesia; ³Department of Epidemiology, Infectious Disease Control and Prevention, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan; ⁴Graduate School of Engineering, Osaka University, Osaka, Japan

Purpose: To compare the reliability and accuracy of intraocular pressure (IOP) measured while wearing soft contact lenses (SCLs) using a non-contact tonometer (NCT), Goldmann applanation tonometer (GAT), iCare rebound tonometer (RBT) and the Tono-Pen XL.
Methods: Twenty-six healthy subjects were examined. The IOP was measured using NCT, GAT, RBT, and the Tono-Pen XL, while the subjects wore SCLs -5.00 D, -0.50 D and +5.00 D. Bland–Altman plots and a regression analysis were used to compare the IOPs obtained with those instruments and the IOPs of the naked eyes measured using GAT (the standard IOPs in this study).
Results: The IOPs obtained by the Tono-Pen XL while the subjects were wearing -5.00 D, -0.50 D, and +5.00 D SCLs were significantly higher than those of the naked eyes obtained using GAT. RBT showed that the IOPs were similar to the GAT standard IOPs under all conditions. The IOPs measured with NCT and GAT while the subjects were wearing -5.00 D and -0.50 D SCLs were similar to the GAT standard IOPs. The IOPs obtained with RBT and NCT while the subjects were wearing -5.00 D and -0.50 D SCLs exhibited a good correlation with the standard IOPs.
Conclusion: The NCT and RBT are best when measuring IOP through hydrogel SCLs.

Keywords: soft contact lens, intraocular pressure, rebound tonometer, non-contact tonometer