Accurate measurement of intraocular pressure (IOP) is a vital component in the screening, diagnosis and management of paediatric glaucoma. Goldmann applanation tonometry (GAT) has been the gold standard method for IOP measurement in adults, but many new alternative methods and devices have been developed in the last few years.Newer methods for IOP measurement are necessitated by certain limitations of GAT, which include its invasiveness, need for topical anaesthesia, slit-lamp mounting with sitting posture, and disinfection of tonometer head after each use,  requirement of an experienced technician, variability of readings depending on corneal material properties, curvature and thickness, and inaccuracy in post-refractive surgery eyes.

The invasiveness of GAT is a major limiting factor in the pediatric population, especially in younger children, who do not cooperate and resist eye examination. A tonometer that produces less sensations on eye contact may be more acceptable to children, who are usually anxious and uncooperative when touched in their eyes by GAT. 

The Icare tonometer® is a rebound tonometer (RBT) that operates on the principle of measuring the motion parameters of a probe that bounces back after making contact with the eye, with higher IOPs resulting in faster rebounds. The impact of the sensor against central cornea is minimal and six readings are obtained in rapid succession without eliciting the blink reflex. Icare is a portable device, doesn’t require topical anesthesia, can be hand-held few millimetres away from the eye, all of which may be less frightening to children.  The probe in icare tonometer has a disposable tip that obviates need for disinfection, but can also be potentially reused after disinfection with less chances of crossifection. In addition, icare can be handled effectively even by less experienced tonometrists. Previous studies in adults have shown that IOP values measured with Icare tonometry (ICT) have a positive bias compared to values of GAT, but ICT can be a reliable method due to its good correlation with GAT, both in healthy and glaucomatous eyes. 

 In the pediatric age group, ICT is a comfortable, accurate and reproducible method with high rates of successful IOP measurement and has been observed to reduce the need for anesthesia.  ICT has been reported to be one of the preferred methods for IOP measurement in children less than ten-years in real life clinical settings.  

The purpose of this study was to compare the agreement in IOP readings taken with Goldmann applanation tonometer and ICare® rebound tonometer in a normal paediatric cohort. 

Null Hypothesis:

IOP measured by Icare tonometer will be not significantly different from that measured by the comparator gold standard Goldmann applanation tonometer

IOP measured by Icare tonometer will have good correlation (Pearsons correlation) and agreement (Bland-Altmann method) with Goldmann applanation tonometer