Comparison of Intraocular Pressure Measurement by Goldmann Applanation Tonometer and Non-Contact Airpuff Tonometer

Doi: 10.36351/pjo.v38i3.1425

Abstract

Purpose: To compare between the intra-ocular pressure (IOP) measured by Goldmann applanation tonometer (GAT) and non-contact air-puff tonometer (APT) considering GAT as gold standard.

Study Design: Comparative analytical study

Place and Duration of Study: Al-Shifa trust eye Hospital, Rawalpindi from January 2018 to June 2018

Methods: Five hundred individuals, 223 glaucoma patients and 277 non glaucoma control subjects were recruited. After taking a detailed history, slit-lamp examination and fundoscopy was performed to check glaucoma status of the eyes. Retinal nerve fiber layer (RNFL) was checked with optical coherence tomography. Non-contact air-puff tonometry of both eyes were performed. Using a drop of local anesthetic and small amount of fluorescein, intra-ocular pressure was measured with GAT (Haag Streit Diagnostics).Central corneal thickness was measured for correction of IOP measurement with GAT. Paired sample correlations were performed to compare the mean IOP with APT and GAT with and without correction factor. Sensitivity and specificity for measurement of IOP by APT was calculated considering GAT as gold standard.

Results: Mean age of the male and female participants was 49.87+18.70years and 45.53+16.91years respectively. Mean IOP in glaucomatous eyes measured by GAT (after applying correction factor) and APT was 16.01+5.57 mmHg and 17.31+7.22 mmHg respectively. The sensitivity and specificity of APT for measuring IOP in glaucomatous eyes were 84.04% and 73.53% respectively.

Conclusion: Non-contact air-puff tonometer has good sensitivity and specificity and can be used reliably for measurement of IOP in out-patient department and for mass screening of the population.