Agreement Between Pentacam and IOLMaster in Patients Undergoing Toric Intraocular Lens Implantation

Abstract

Purpose: : To investigate agreement between the OCULUS Pentacam and Zeiss Humphrey IOLMaster in measuring corneal power, astigmatism, and axis in eyes undergoing toric intraocular lens implantation.

Methods: : Consecutive eyes undergoing phacoemulsification with toric intraocular lens implantation were retrospectively studied. Corneal power, astigmatism, and axis were pre-operatively measured in 41 subjects (49 eyes) by Pentacam and IOLMaster. Mean corneal power and astigmatism values were calculated for both technologies with Bland-Altman plots used to investigate agreement. Mean absolute difference in axis measurements were compared between both technologies.

Results: : Mean keratometry values for Pentacam and IOLMaster (43.3D±1.6 and 43.2D ±1.6, respectively) demonstrated no statistically significant difference (p=0.68). The 95% limits of agreement were moderate at -1.02 to +1.13 with a mean difference of 0.05±0.55 (SD). Mean corneal astigmatism values also demonstrated no statistically significant difference (Pentacam: 2.29D ±0.79, IOLMaster: 2.43D±0.83, p=0.12) but showed wide 95% limits of agreement ranging from -1.37 to +1.09 and a mean difference of -0.14±0.63 (SD). Mean axis measurements were relatively similar (Pentacam 95.0 degrees±49.4, IOLMaster 95.4 degrees±53.1) but mean absolute difference in axis measurements was 8.9 degrees (range: 0.3 to 37.7, SD 8.79). Thirty percent of patients had a 10 degree or greater difference in axis measurements and 13% of patients had a 20 degree or greater difference in measurements.

Conclusions: : Although Pentacam and IOLMaster provide similar mean values for corneal keratometry, astigmatism, and axis in patients undergoing toric IOL implantation, they cannot be used interchangeably due to variability between the two modalities, particularly for astigmatism and axis. Since neither modality is currently accepted as a "gold standard" of measurement, further studies are needed to determine which device results in superior post-surgical refractive outcomes.

Keywords: intraocular lens • imaging/image analysis: clinical