The Measurement of Intra-Ocular Pressure Over Low Minus Soft Contact Lens by Air Puff Non-Contact Tonometer

Abstract

The measurement of intraocular pressure (IOP) over silicone hydrogel contact lenses by non-contact tonometer (NCT) could be applied in ophthalmologic practice but the accuracy of the measurement is still controversial. Previous research has proven that power and material of contact lenses being the factors that influence the values of IOP. The aim of this study is to evaluate the effect of low power spherically designed silicone hydrogel contact lenses on values of IOP measured by NCT. We measured IOP with and without silicone hydrogel contact lenses on 38 subjects (16 male and 22 female) who did not have any ocular or systemic diseases. The One-way repeated measures ANOVA showed statistically significant higher values of IOP measurement over contact lenses immediately after wearing (13.19 ± 2.47 mmHg) and two hours after wearing (13.26 ± 2.48 mmHg) compared to those measured without contact lenses (13.03 ± 2.56 mmHg), p = 0.041 and p = 0.028 respectively. There was no significant difference on IOP measurement between immediately and after two hours of contact lens wear, p = 1.000. Independent t-test showed there was no significant difference between male and female IOP, p = 0.206. In conclusion, silicone hydrogel contact lenses give significant changes in IOP measurement thus need to be removed for IOP measurement.

Keywords: Intraocular pressure; tonometry, ocular; contact lenses