Intraocular Pressure Measurement in Childhood Glaucoma under Standardized General Anaesthesia: The Prospective EyeBIS Study

Abstract

Objective: We aimed to compare intraocular pressure (IOP) measurements using iCare® PRO rebound tonometry (iCare) and Perkins applanation tonometry (Perkins) in childhood glaucoma subjects and healthy children and the influence of anaesthesia depth, age and corneal thickness. Material: Prospective clinical, case-control study of children who underwent an ophthalmologic examination under general anaesthesia according to our protocol. Children were 45.45 ± 29.76 months old (mean ± SD (standard deviation)). Of all children, 54.05% were female. IOP was taken three times (T1–T3), according to duration and the depth of anaesthesia. The order of measurement alternated, starting with iCare. Agreement between the device measurements was evaluated using Bland–Altman analysis. Results: 53 glaucoma subjects and 22 healthy controls. Glaucoma subjects: IOP measured with iCare was at T1: 27.2 (18.1–33.8), T2: 21.6 (14.8–30.6), T3: 20.4 mmHg (14.5–27.0) and Perkins 17.5 (12.0–23.0), 15.5 (10.5–20.5), 15.0 mmHg (10.5–21.0) (median ± IQR (interquartile range)). Healthy controls: IOP with iCare: T1: 13.3 (11.1–17.0), T2: 10.6 (8.1–12.4), T3: 9.6 mmHg (7.7–11.7) and Perkins 10.3 (8.0–12.0), 7.0 (5.5–10.5), 7.0 mmHg (5.5–8.5) (median ± IQR). The median IOP was statistically significantly higher with iCare than with Perkins (p < 0.001) in both groups. The mean difference (iCare and Perkins) was 6.0 ± 6.1 mmHg for T1–T3, 7.3 at T1, 6.0 at T2, 4.9 mmHg at T3. Conclusion: The IOP was the highest in glaucoma subjects and healthy children at T1 (under sedation), independently of the measurement method. iCare always leads to higher IOP compared to Perkins in glaucoma and healthy subjects, regardless of the duration of anesthesia.

A comparison of rebound and applanation tonometry in children with and without primary congenital glaucoma

“…Previous literature has reported RBT to overestimate IOP in children with 13,14,15,16 and without glaucoma. 12,21 This study data correlate with these findings, regardless of the clinical group.…”

“…12 In the study analysis, the difference in IOP between RBT and AT was most pronounced in the PCG group. Strzalkowska et al 13 reported a mean IOP difference between RBT and AT of 6.0 mmHg ± 6.1 mmHg in their study investigating the optimal timing of measuring IOP in children with and without PCG undergoing anaesthesia.…”

“…12 The reliability, however, still needs to be established in the paediatric population. Some previous studies comparing RBT to AT in paediatric patients with PCG have found that RBT overestimates IOP compared to AT, 13,14,15,16 while others 17 found RBT to be comparable. There is, therefore, clinical equipoise regarding whether there is a significant difference between RBT and AT when comparing PCG eyes to non-PCG eyes under general anaesthesia without the potential effect of the volatile agents.…”

It Is All about Pressure

“…In the article entitled "Intraocular pressure measurement in childhood glaucoma under standardized general anesthesia: the prospective EyeBIS study", Alicja Strzalkowska et al [12] addresses the important topic of the IOP measurement in children. The authors compared the IOP measurements taken with the iCare PRO rebound tonometer and Perkins applanation tonometer in glaucomatous and healthy children (mean age of 45 ± 30 months) under general anesthesia.…”