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Stephanie Jones, Pouya Alaghband, Alba De Antonio Ramírez, Elizabeth Galvis, K Sheng Lim; Rebound Tonometry as an Alternative Method of Intraocular Pressure Measurement in Aqueous Humour Dynamics Studies.. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5321.
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© ARVO (1962-2015); The Authors (2016-present)
Pneumatonometry is used to measure intraocular pressure (IOP) in aqueous humour dynamics studies (ADS) but it may bias flurophotometric data. The pneumatonometer probe indents the cornea, temporarily disrupting its surface. This may disrupt uniformity of corneal fluorescein distribution leading to inaccurate fluorophotometric scans. Our aim is to establish a better method of IOP measurement. In a cross-sectional, observational study we used both pneumatonometry (Model 30 Pneumatonometer, Reichert Inc., Depew USA) and rebound tonometry (iCare TAIO1i, ICare Finland Oy, Vantaa Finland). The iCare has negligible corneal contact. Both methods have shown agreement with Goldmann tonometry. We hypothesise rebound tonometry is as good as pneumatonometry for measuring IOP.
We identified 180 eyes of 90 participants from our database. We performed pneumatic and rebound IOP measurements four times with the average of three measures taken per timepoint. We performed Goldmann tonometry on visit completion. We randomly selected one eye per participant. We took numerical differences between pneumatonometry and rebound tonometry as the primary outcome. We used the Intraclass Correlation Coefficient (ICC), Bland-Altman plot and Mann-Whitney U test to assess the primary outcome.
Shapiro-Wilk showed normally distributed log-transformed data (n=88; Reichert; W= 0.98, p=0.22, iCare; W=0.98, p=0.14). ICC was acceptable (n=88, ICC Average measures 0.84, CI 0.75 to 0.89). Bland-Altman demonstrated a point majority within the 95% agreement limit (n=88, Arithmetic mean 0.09, 95% CI 0.03 to 0.15, p=0.0030, Lower Limit SD -0.44, 95% CI -0.54 to -0.34, Upper Limit SD 0.62, 95% CI 0.52 to 0.72, Coefficient of Repeatability 0.56). Mann Whitney U did not reach statistical significance (n=88 p=0.12, 95% CI 2.71 to 2.84 (sample 1), 2.67 to 2.81 (sample 2)).
We consider rebound tonometry an acceptable alternative to assess IOP in ADS based on our results, which failed to find significant differences, but more research is needed on this topic.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Table 1. Description of Baseline Characteristics.
Figure 1. Bland-Altman Plot for Comparison of Pneumatonometry and Rebound Tonometry.
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