Comparison of intraocular pressure with Icare tonometer and applanation tonometer in paediatric age group

Accurate measurement of intraocularpressure (IOP) is a vital component in the screening, diagnosis and managementof paediatric glaucoma. Goldmann applanation tonometry (GAT) has been the goldstandard method for IOP measurement in adults, but many new alternative methodsand devices have been developed in the last few years.Newermethods for IOP measurement are necessitated by certain limitations of GAT,which include its invasiveness, need for topical anaesthesia, slit-lampmounting with sitting posture, and disinfection of tonometer head after eachuse,  requirement of an experiencedtechnician, variability of readings depending on corneal material properties,curvature and thickness, and inaccuracy in post-refractive surgery eyes.

The invasiveness of GAT is a majorlimiting factor in the pediatric population, especially in younger children,who do not cooperate and resist eye examination. A tonometer thatproduces less sensations on eye contact may be more acceptable to children, whoare 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 aprobe that bounces back after making contact with the eye, with higher IOPsresulting in faster rebounds. The impact of the sensor againstcentral cornea is minimal and six readings are obtained in rapid successionwithout eliciting the blink reflex. Icare is a portable device, doesn’t requiretopical anesthesia, can be hand-held few millimetres away from the eye, all ofwhich may be less frightening to children. The probe in icaretonometer has a disposable tip that obviates need for disinfection, but canalso be potentially reused after disinfection with less chances ofcrossifection. In addition, icare can be handled effectively evenby less experienced tonometrists. Previous studies in adults have shownthat IOP values measured with Icare tonometry (ICT) have a positive biascompared to values of GAT, but ICT can be a reliable method due to its goodcorrelation with GAT, both in healthy and glaucomatous eyes.

Inthe pediatric age group, ICT is a comfortable, accurate and reproducible methodwith high rates of successful IOP measurement and has been observed to reduce theneed for anesthesia. ICT has been reported to be one ofthe preferred methods for IOP measurement in children less than ten-years inreal life clinical settings.

Thepurpose of this study was to compare the agreement in IOP readings taken withGoldmann applanation tonometer and ICare® rebound tonometer in a normal paediatriccohort.

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