Agreement between Swept Source OCT Based and Scheimpflug / Placido Based Biometry Devices

Abstract

Purpose: To assess the agreement between a swept source OCT based IOL Master 700 biometer and a dual Scheimpflug ray tracing analyser, Galilei G6. to measure various parameters of biometry in cataractous eyes.

Study Design: Prospective Cross Sectional.

Place and Duration of Study: Amanat Eye Hospital, Islamabad from April 2016 to June 2016.

Material and Methods: The 206 eyes of 110 patients scheduled for cataract extraction (consecutive sampling) were subjected to scanning by both devices by a single trained operator. Measurements recorded by each machine included keratometry (K), axial length (AL), astigmatism, anterior chamber depth (ACD), central corneal thickness (CCT), lens thickness (LT), white to white (WTW) and intraocular lens (IOL) power. The statistical package for social sciences software (SPSS version 22) and microsoft excel 2010 were applied to organize and tabulate the data collected. Paired T test was applied with 95% confidence interval to determine the association between parameters calculated with IOL Master 700 and Galilei 6.

Results: The mean age was 62.74 years (±12.78) SD. In the sample of 206, frequency of IOL Master 700 failure was 3 (1.46%) and frequency of Galilei 6 failure was 59 (28.6%).

High correlation was seen in CCT (r = 0.976), WTW

(r = 0.731) and LT (r = 0.958) measurements. However, there was statistically significant disagreement in keratometry (Kavg.; p < 0.001) measurements and ACD measurements and clinically significant difference in the mean AL measurements which eventually impacted the IOL power estimated by both devices.

Conclusion: Significant disagreement between these two devices was noted and hence they cannot be used interchangeably

Keywords: Biometry; Swept Source OCT based IOL Master 700; Galilei G6; Intraocular Lens; Target Refraction.