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Deepak Sambhara, Christopher Hill, Lisa Hart, Jufu Chen, Ingrid U Scott, Seth Pantanelli; Effect of Applanation Tonometry on Keratometry Measurements Obtained with IOLMaster and Galilei Dual-Scheimpflug Analyzer. Invest. Ophthalmol. Vis. Sci. 2016;57(12):922.
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© ARVO (1962-2015); The Authors (2016-present)
Accurate keratometry measurements are essential to determine the optimal intraocular lens (IOL) power for implantation during cataract surgery. Tonometry is performed routinely in the preoperative work-up of cataract patients. The purpose of this study is to investigate the effect of tonometry on keratometry measurements.
Keratometry measurements were performed on 36 eyes from 21 patients with IOLMaster® 5 (Carl Zeiss Meditec) and Galilei G4 dual-Scheimpflug analyzer® (Ziemer Group) immediately before and after applanation tonometry with Tono-Pen XL® (Reichert Technologies). Kflat, Ksteep power, and Ksteep axis values were obtained with IOLMaster, and SimK flat, SimK steep power, and SimK steep axis values were obtained with Galilei dual-Scheimpflug analyzer®; measurements obtained before and after applanation tonometry were compared using paired t-test analyses. A difference of 0.25 diopters (D) or more between pre- and post-applanation is considered clinically meaningful. A p-value < 0.05 is considered statistically significant.
The difference between pre- and post-applanation Ksteep was 0.17 D (p=0.0125). The difference between pre- and post-applanation SimK steep measured by G4 was 0.07 D (p=0.0063). The mean difference in spherical equivalent (SE) pre- versus post-applanation was 0.066 D (p=0.108) when IOLMaster was used, and 0.064 D (p=0.0021) when G4 was used. No other statistically significant differences, and no clinically meaningful differences, were observed with regards to changes in the axes or the flat meridian power measurements before versus after applanation tonometry.
Applanation tonometry with Tono-Pen XL® (Reichert Technologies) is not associated with a clinically meaningful change in keratometry measurements or SE obtained with IOLMaster and Galilei dual-Scheimpflug analyzer.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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