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Gregory Richard, Kimberly Williams Crowder, Omalola Idowu, Jorge Jimenez; Measuring Intraocular Pressure with Disposable Versus Reusable Applanator Prisms. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):103.
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© ARVO (1962-2015); The Authors (2016-present)
The current gold standard for measuring intraocular pressure (IOP) is Goldmamn applanation tonometry (GAT) due to its simple mechanics and relatively low cost. Due to concerns for infection and utilization of time and resources for sterilization, there is reason to establish the efficacy of alternative measurement devices. The purpose of the study is to compare the correlation of IOP between the reusable Goldmann applanator tips and two disposable prism tips: the Carleton Optical Tonojet and Haag-Streit Tonosafe.
A total of 50 patients participated in the study, and both eyes from each patient were included in the data (n = 100). The first 25 patients (n = 50) underwent applanation on each eye with both the Goldmann Applanation Tonometer and the Carleton Optical Tonojet applanation tip. The last 25 patients (n = 50) underwent applanation on each eye from both the Goldmann Applanation Tonometer and the Haag-Streit Tonosafe applanation tip. Prior to applanation, a technician set the pressure dial to 0 and placed the tip into position. The physician then performed applanation on one eye, and the technician recorded the measured IOP and type of applanator tip used. The technician then reset the dial to 0, and the physician measured the fellow eye in the same manner. This process was then repeated using the alternate applanator tip.
For the first 50 eyes, the mean IOP using the Goldman applanation tip was 14.41. In the same set of eyes, the Tonojet applanation tip was found to have a mean IOP of 13.86. There was a mean difference of 0.55 mmHg and a standard deviation of 1.75 mmHg. The range of deviation was - 5.00 to 4.00. The intraclass correlation was 0.904 for the Tonojet tip (p < .001).<br /> <br /> For the last 50 eyes, the mean IOP using the Goldman applanation tip was 17.1. In the same set of eyes, the Tonosafe applanation tip was found to have a mean IOP of 17.22. There was a mean difference of 0.12 mmHg and a standard deviation of 1.48 mmHg. The range of deviation for the Tonosafe was - 3.00 to 3.00. The intraclass correlation was 0.955 for the Tonosafe tip (p < .001).
In summary, the Tonosafe prism is more expensive with a smaller mean difference and standard deviation as well as a stonger intraclass correlation versus traditional Goldman tonometry than the Tonojet prism. GAT remains the standard, but Tonosafe is the more accurate of the two disposable types tested.
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