Abstract
Purpose: :
To evaluate and compare the reliability and repeatability of intraocular pressure (IOP) measurements using the new ICare® rebound tonometer (ICT) and the Tonopen XL® Tonometer (TP) in premature infants.
Methods: :
69 premature infants aged 25 to 35 (mean 28.4) weeks were examined in their 40th week of gestation (SD=10 weeks) during the screening for retinopathy of prematurity. 142 eyes of 71 infants were measured by ICT (three measurements per eye), 56 eyes of 28 infants by ICT and TP (three measurements per eye and per methode). Because of known impact of anesthetic eyedrops on IOP, we first performed ICT measurements, followed by TP in local anesthesia (Proxymetacain-HCl 0.5%-eye drops). TP was performed three minutes after eye drop application. A linear regression model correlated the deviations of ICT and TP (SPSS 15.0).
Results: :
Mean IOP was 9 mmHg for ICT (SD 2.2 mmHg) and 16 mmHg for TP (SD 4.4 mmHg). IOP measurements were found to read significantly higher with TP compared to ICT (p<0.01).
Conclusions: :
IOP values are significantly lower evaluated by ICT than by TP. Thus ICT seem to better reflect the known infant IOP. Tonopen measurements are probably falsely elevated due to defense and discomfort reactions of the premature baby to the anaesthetic eye drop instillation and bigger size of eyelid opening width due to the larger applanation area of the Tonopen.
Keywords: intraocular pressure • clinical research methodology • retinopathy of prematurity