An indirect method to compare the reference centres for corneal measurements.

Area of Science:

• Ophthalmology
• Optometry
• Biomedical Engineering

Background:

• Corneal measurements often rely on a reference center, but its location can differ between diagnostic devices.
• Variability in reference center definitions can complicate the direct comparison of data from different corneal measurement systems.

Purpose of the Study:

• To develop and validate a method for comparing reference centers used in corneal measurement systems.
• To assess the comparability of reference centers between the Pentacam HR (Scheimpflug imaging) and ATLAS (Placido-ring topography) systems.

Main Methods:

• An indirect comparison method was employed, utilizing the pupil center and its offset from the reference center.
• Reference centers of the Pentacam HR and ATLAS systems were compared in 30 subjects' right and left eyes.
• Statistical analysis included testing differences and correlations of pupil center offsets, with Bland-Altman analyses.

Main Results:

• No statistically significant differences were found in mean pupil offsets between the Pentacam HR and ATLAS systems for either eye (p > 0.05).
• Strong correlations were observed for pupil center offsets between the two systems for both right and left eyes (r values ranging from 0.93 to 0.98, p < 0.0001).
• Bland-Altman analyses confirmed no significant differences in pupil center offsets, supporting the systems' reference center similarity.

Conclusions:

• The Pentacam HR and ATLAS corneal measurement systems exhibit highly similar reference centers.
• Data from the Pentacam HR and ATLAS systems can be directly analyzed, irrespective of using the corneal vertex or pupil center as the reference.
• This finding simplifies cross-platform data analysis in corneal diagnostics.