Comparative analysis of anterior corneal surface characteristics measured by two topographers and two autokeratometers

Background: Precise quantification of corneal parameters enhances the clinical of the anterior corneal surface for various clinical assessments, with ongoing research focusing on optimizing everyday practice through device comparison studies. The study aimed to compare the agreement on the anterior corneal surface characteristics values measured by four commercially available devices: EyeSys 2000, Oculus Easygraph, ARK700A and ARK510A. Methods: Observational cross-sectional study involving 50 eyes from healthy volunteer recruited among subjects attending for an eye examination. Corneal radius minimum keratometry reading (min-K) and maximum keratometry reading (max-K), astigmatism axis and eccentricity were measured in all participants with EyeSys, Oculus Easygraph, ARK700A and ARK510A. Measurements were performed three times only in the right eye in random order by four optometrists who were unaware of the results of the other researchers. Results: A statistically significant difference occurred for the measurements of the corneal radius (Greenhouse-Geisser and Huynh-Feldt: P≤0.001 for both max-K and min-K radius) and the axis of astigmatism (Friedman: P<0.001), between the four devices. Pairwise comparisons revealed no radius differences between Oculus Easygraph and ARK510A (Sidak: min-K radius, P=0.231; max-K radius, P=0.224), and no axis differences in all pairwise analyses that have not imply the EyeSys (Wilcoxon: all P≥0.130). There was no statistical difference in the eccentricity value obtained by the topographers (paired t-test: P=0.507). Conclusions: The present study showed that EyeSys 2000 measurements differed from those of the other devices across all parameters. Alternatively, both topographers showed a perfect agreement concerning eccentricity measurements in everyday practice.