Comparison of biometric parameters between a Scheimpflug‐based partial coherence interferometer and swept‐source OCT biometer in a Canadian population

Author Block: Andrew C. W. Robart 1, Davin Johnson 2, Erin Dohaney 2. 1Memorial University,
2Queen's University.

Author Disclosure Block:  A.C.W. Robart:  None.  D. Johnson:  None.  E. Dohaney:  None.

Abstract Body: 

Purpose: 

To compare biometric parameters between the Pentacam AXL and IOL
master 700 in a Canadian population of patients undergoing cataract surgery and refractive lens
exchange. 

Study Design: Quantitative retrospective cohort study. 

Methods: This retrospective
review was conducted by analyzing all patients receiving either cataract surgery or refractive lens
exchange at a private surgical centre in Ottawa, Ontario, Canada over a 9‐month period between
July 2021 and March 2022. We compared axial length (AL), anterior chamber depth (ACD), white‐towhite
(WTW), and keratometry measurements between the Pentacam AXL and IOL Master 700. Deidentified
data collection was automated using optical character recognition (OCR) in Powerapps AI,
which sorted data into Excel. All statistical analyses including paired two‐way t‐tests and vector
algebra were completed using Prism 9 (GraphPad Software Inc, San Diego, CA, USA). 

Results: The study population consisted of a total of 655 eyes from 328 patients with a mean age of 61 years
(range 29 ‐ 85 years). IOL master 700 measurements were completed for all patients, whereas in
3.7% of eyes the Pentacam AXL acquisition was unsuccessful due to the density of the cataract.
Statistically significant differences were seen between the two devices with respect to WTW (12.1 vs
11.8 mm, p<0.0001), ACD (3.27 vs 3.30 mm, p <0.0001), and mean keratometric astigmatism (0.9 vs
1.1 D, p = 0.025). No statistically significant differences were seen between the 2 devices with
respect to AL (24.17 vs. 24.01 mm, p = 0.054) or mean keratometric power (43.44 vs. 43.40 D, p =
0.30), however, the difference in AL is potentially clinically significant. 

Conclusions: The IOL Master 700 and Pentacam AXL are not interchangeable devices for pre‐operative measurements. Of great clinical significance is a mean difference of 0.3mm in WTW between the 2 devices. This has
important implications for both refractive lens exchange/cataract surgery as well as other refractive
procedures including phakic IOL placement.