The Effect of Moderate Powered Soft Contact Lenses On Rebound Tonometry.

Background: Rebound tonometry is a method of measuring intraocular pressure (IOP)
that does not require the use of corneal anesthesia. In the clinical setting, rebound
tonometry is often used as a screening of IOP in pediatric patients and for those who are
apprehensive of applanation tonometry. IOP screenings are often done as part of a pretesting regimen, during which a patient may be wearing contact lenses. The purpose of this study is to determine if rebound tonometry performed with ICare® provides an
accurate measure of IOP through moderate powered soft contact lenses.
Methods: In a sample size of 32 subjects, baseline intraocular pressures were taken in both eyes without any contact lenses. IOPs were then taken with a +5.00 diopter (D) soft contact lenses in the right eye, followed by a -5.00 D soft contact lens in the left eye.
Results: Intraocular pressures measured through a -5.00 D soft contact lens were found to be accurate compared to baseline readings, with a mean difference of 0.6875+0.4270 mmHg. Increased intraocular pressure measurements through a +5.00 D contact lens compared to baseline were found to be statistically significant, with a mean difference of 4.0000+0.4579 mmHg.
Conclusions: While the measurement of intraocular pressure over a moderate powered minus lens is not significantly different than baseline, the practitioner should be aware that the rebound tonometer will increase its overestimation on intraocular pressure as the center thickness of the soft contact lens increases.