Intraocular pressure measurement by three different tonometers in primary congenital glaucoma.

Athar Zareei,Mohammadreza Razeghinejad,Mohammadhosein Nowroozzadeh,Yadollah Mehrabi,Mohammad Aghazadeh-Amiri

doi:10.4103/2008-322x.156105

Abstract

Purpose:To determine the agreement between intraocular pressure (IOP) measurements using an automated non-contact tonometer (NCT), Goldmann applanation tonometer (GAT), and the ocular response analyzer (ORA) in subjects with primary congenital glaucoma (PCG).Methods:Twenty-nine eyes of 17 PCG patients underwent IOP measurements using NCT, GAT and ORA. Variables obtained by the ORA were corneal-compensated IOP (IOPcc), Goldmann-correlated IOP (IOPg), corneal hysteresis (CH), and corneal resistance factor (CRF). A difference more than 1.5 mmHg for IOP was considered as clinically relevant.Results:Mean age of the patients was 12 years. Mean IOP (±standard deviation, SD) was 15.3 ± 2.8 mmHg (GAT), 15.5 ± 6.0 (NCT), 19.2 ± 7.0 (IOPg), and 21.1 ± 7.9 (IOPcc); (P = 0.001). Except for NCT vs. GAT (P = 1.0), the average IOP difference between each pair of measurements was clinically relevant. The 95% limits of agreements were − 10.2 to 10.3 mmHg (NCT vs. GAT), −7.8 to 15.3 (IOPg vs. GAT), and − 8.1 to 19.0 (IOPcc vs. GAT). The differences in IOP measurements increased significantly with higher average IOP values (r = 0.715, P = 0.001, for NCT vs. GAT; r = 0.802, P < 0.001, for IOPg vs. GAT; and r = 0.806, P < 0.001, for IOPcc vs. GAT). CH showed a significant association with differences in IOP measurements only for IOPcc vs. GAT (r = 0.830, P < 0.001).Conclusion:Mean IOP obtained by NCT was not significantly different from that of GAT, but ORA measured IOPs were significantly higher than both other devices.

Highlights

Primary congenital glaucoma (PCG) is responsible for approximately 5% of childhood blindness.[1]
The difference between average intraocular pressure (IOP) values measured by non‐contact tonometer (NCT) and Goldmann applanation tonometer (GAT) (0.2 mmHg; P = 1.0; 95% CI: −3.3 to 3.7, multiple comparison test with Bonferroni correction) was not clinically or statistically significant
IOPcc vs. GAT (5.7 mmHg; P = 0.023; 95% CI: 0.6 to 10.8), NCT vs. IOPg (−3.6 mmHg; P = 0.047; 95% CI: −7.2 to − 0.03), and NCT vs. IOPcc (−5.5 mmHg; P = 0.014; 95% CI: −10.1 to − 0.9) revealed both clinically and statistically significant differences

Summary

Introduction

Primary congenital glaucoma (PCG) is responsible for approximately 5% of childhood blindness.[1] PCG is diagnosed clinically in a neonate or infant by detecting the typical sign and symptoms of photophobia, epiphora, globe enlargement, corneal edema and opacification, and ruptures of Descemet’s membrane (Haab’s striae).[2,3] All corneal changes as well as globe enlargement and optic disc cupping result from elevated intraocular pressure (IOP).[4] Clinical optic nerve head evaluation, Received: 27-07-2013. Accepted: 14-07-2014 gonioscopy, computerized perimetry, and other ophthalmic examinations are difficult to perform in children. IOP reduction is the only method of glaucoma treatment for which there is extensive evidence. Accurate IOP measurement represents a key factor to proper diagnosis, treatment and follow‐up in PCG patients

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Conclusion