Intraocular pressure by noncontact tonometry over an amniotic membrane patch in humans

To determine the reliability of noncontact tonometry (NCT) in measuring intraocular pressure (IOP) over a combination of amniotic membrane (AM) patch and therapeutic soft contact lens (TSCL) in normal human eyes.

Experimental study.

Twenty-five healthy volunteers (twenty males, five females) participated in this study. After topical anesthesia, IOP was measured using noncontact tonometry before and after the application of a single layer of AM to the right eye and a double layer of AM to the left eye. To enable the IOP measurement by NCT, a TSCL was placed over the AM patch. The thickness of a single or a double layer of AM was measured by pachymetry and correlated with the IOP reading.

We found no statistical difference between IOPs measured with and without a combination of a single-layer AM/TSCL (P = .734). In contrast, the IOPs measured over a combination of a double-layer AM/TSCL decreased significantly when compared with the control (P < .0001). The average thicknesses of the single and the double layer of AM were 72.4 +/- 15.0 mum and 126.9 +/- 14.6 mum (mean +/- SD), respectively. There was a negative correlation between total AM thickness and IOP change (r = -.481, P = .0008).

We found that it is reliable to measure IOP by NCT through a combination of a single-layer AM/TSCL on normal human eyes. However, IOP measured by NCT over a combination of a double-layer AM/TSCL was inaccurate and tended to be an underestimation.