Agreement in anterior eye measurements between the Aladdin biometer and Medmont E300 topographer

Agreement in anterior eye measurements between the Aladdin biometer and Medmont E300 topographer


Kristina Mihic, Chris Hull, Byki Huntjens


Purpose: Superiority in corneal diameter, white-to-white (WTW) distance, measurements using objective imaging devices over subjective face-to-face measurements by eye care practitioners (ECP) have been reported previously. The primary aim of this study was to compare manual and automated corneal diameter measurements using 2 different objective imaging devices. A secondary aim was to compare results obtained by an experienced ECP and novice user.

Method: The WTW distance was measured in one eye selected at random from 71 participants (males n=15, females n=56) using the automated software v1.6.2 of the Aladdin biometer (Topcon, Tokyo, Japan) and manual ruler and circumference methods within the Medmont E300 topographer software v6.2.6 (Medmont International Pty Ltd., Victoria, Australia). The mean age of the participants was 20.9 years ± 2.1 (SD) ranging 19 to 27 years and none had any history of ocular disease. Both examiners, independently measured WTW on three different occasions for both techniques on the Medmont.

Results: The ECP recorded a mean corneal diameter of 11.87 mm ± 0.37 (SD) with the Aladdin, while the Medmont measured 11.91 ± 0.37 mm using the ruler and 11.90 ± 0.36 mm using the circle (F(69) = 1.677; p = 0.19). The Intraclass Correlation Coefficients (ICC) of 3 repeated measures was 0.993 (ruler) and 0.930 (circle). Compared to the ECP, this was reduced in the novice user (0.968 and 0.955, respectively) with increased variability (p = 0.051). The coefficient of inter-rater repeatability improved using the circumference method (0.937) versus the ruler (0.914).

Conclusions: There were no statistically nor clinically significant differences between the WTW measurements using the Aladdin or Medmont; therefore these can be used interchangeably. However, when analysing Medmont images, the ruler method was more reliable compared to the circle. Additionally, we report increased variation in repeated measures by the novice user, indicating that some training may be necessary.

1st Author Biography: After completing her BSc in optometry in the Netherlands, Byki moved to the UK in 2002 to study an MSc and PhD at the University of Manchester. In 2009 she joined the academic staff of City, University of London. As a senior lecturer and optometry lead for teaching excellence within the School of Health Sciences, she is responsible for contact lens teaching on UG and PG level, and supervisor of several MSc and PhD students. Her research interests are dry eye and (myopia control) contact lenses.

*Data correct at the time of submission to BCLA by NCC.