Correlation of Corneal and Scleral Pneumatonometry in Pediatric Patients

Purpose: To study the correlation between corneal and scleral intraocular pressure (IOP) by pneumatonometry in pediatric patients. Design: Cross-sectional study. Participants: Patients (age range, 0-15 years) undergoing an eye examination under anesthesia or eye surgery were recruited at the University of California, San Francisco, Benioff Children's Hospital between July 2015 and April 2016. Methods: Intraocular pressure measurements were obtained by pneumatonometry on the central cornea and the inferonasal and inferotemporal sclera in a random order. Spearman correlations between corneal versus inferonasal scleral IOP and corneal versus inferotemporal scleral IOP were calculated. A linear mixed-effect model was used to derive a predictive equation for corneal IOP from scleral IOP and to perform covariate analysis for age, axial length, central corneal thickness, and lens status. The standard deviation of the predicted corneal IOP was determined by bootstrap mixed-effect regression analysis. Main Outcome Measures: The predictive model of corneal IOP from scleral IOP. Results: Seventy-five eyes from 40 patients were included in the study. Spearman correlation coefficient for corneal versus inferotemporal scleral IOP was 0.79 (P < 0.01) and 0.48 for corneal versus inferonasal scleral IOP (P < 0.01). Corneal IOP may be predicted from scleral IOP via the following equations: corneal IOP = 0.73 + inferotemporal scleral IOPthorn7.45 and corneal IOP = 0.21 + inferonasal scleral IOP thorn17.83. Central corneal thickness (P = 0.07), lens status (P = 0.4), age (P = 0.33), and axial length (P = 0.15) did not affect significantly the relationship between corneal and scleral IOP in the multivariate regression analysis. The standard deviation of predicted corneal IOP was less than 1.2 mmHg within an inferotemporal scleral IOP range of 10 to 35 mmHg. Conclusions: In children, corneal and scleral IOP are correlated significantly when measured by pneumatonometry. Measurements obtained from the inferotemporal sclera are better predictors of corneal IOP than those obtained from inferonasal sclera. Pneumatonometry on the inferotemporal sclera may be an alternative method to estimate IOP for pediatric patients from whom corneal IOP measurement is difficult to obtain. Published by Elsevier on behalf of the American Academy of Ophthalmology