A Comparative Study of Intraocular Pressure Measurement by Different Tonometer in Patients Attending Tertiary Care Hospital

Background and Objectives: Raised intraocular pressure is a well-known causative risk factor for the development of glaucoma. It is also the only component of glaucoma that is amenable to medical or surgical intervention, provided it is detected early enough. The measurement of intraocular pressure has evolved over time with the advent of a myriad of newer tonometers – one such being the non-contact tonometer. This study has been embarked upon with the objective of comparing the non-contact tonometer with the gold standard. Goldmann applanation tonometer versus the Schiotz tonometer, one of the most popularly used tonometers in the developing world. It also aims to establish the value of the non-contact tonometer as a screening tool. Materials and Methods: 200 purposively selected patients were subjected to three methods of tonometry; Goldmann applanation tonometry, Perkins Tonometry and Schiotz indentation tonometry (with the 5.5g, 7.5g and 10g weights); on both eyes. Three recordings were obtained with each method and the arithmetic mean taken as the intraocular pressure. The data was statistically analyzed using the intra-class correlation coefficient. Results: The non-contact tonometer showed excellent agreement with the Goldmann applanation tonometer compared to the Schiotz tonometer which showed only a fair agreement. Interestingly, the left eyes showed better agreement on noncontact tonometry than the right eyes, a phenomenon we attribute to apprehension of the patients on their first experience with the air puff. The non-contact tonometer also scored high as an effective screening tool. Conclusion: The non-contact tonometer compares favorably with the Goldmann applanation tonometer and can be reliably used as a screening tool. However, in view of the varying degrees of comparison between the two eyes, its role in monitoring glaucomatous eyes needs to be further evaluated.