Scleral Pneumatonometry in Penetrating Keratoplasty: A Clinical Study
To evaluate the reliability between pneumatonometry intraocular pressure (IOP) measurement in different scleral locations and corneal IOP in a penetrating keratoplasty (PK) setting. Our aim is to validate a method that can potentially be used for patients with keratoprostheses.Methods:
This is a prospective observational study of 40 patients who underwent monocular PK by a single surgeon and had no significant anterior segment condition in the contralateral eye. Participants were recruited during routine visits to the Cornea Clinic at the Stein Eye Institute, between November 2016 and February 2017. Goldmann applanation tonometry, central corneal pachymetry, and inferior, inferotemporal, and temporal scleral pneumatonometry of both eyes were collected.Results:
The correlation coefficient between corneal Goldmann applanation tonometry IOP and inferior, inferotemporal, and temporal scleral pneumatonometry IOP in the transplanted eye found that all locations were significantly and strongly correlated (r = 0.76, r = 0.80, and r = 0.75, respectively; P < 0.001). The correlation coefficient was higher for inferior and inferotemporal scleral measurements when the contralateral eye was used to predict the PK corneal IOP (r = 0.85 and r = 0.79, respectively; P < 0.001) and weaker for temporal measurement (r = 0.72; P < 0.001). Central corneal thickness correction formulas did not improve the correlation between scleral and corneal IOPs. All linear regression analyses were statistically significant (P < 0.001).Conclusions:
The inferotemporal sclera was the optimal location for pneumatonometry IOP measurement. The contralateral eye could be used to more accurately predict the IOP in the eye of interest. Scleral pneumatonometry is an intuitive and reliable method to monitor IOP when corneal measurement is not available.