Corneal thickness mapping by 3D swept-source anterior segment optical coherence tomography

Area of Science:

• Ophthalmology
• Biomedical Optics
• Medical Imaging

Background:

• Accurate central corneal thickness (CCT) measurement is crucial for diagnosing and managing various ocular conditions.
• Different pachymetry devices, including optical coherence tomography (OCT) and ultrasound, are used for CCT assessment.
• Evaluating the accuracy and repeatability of these devices is essential for clinical practice.

Purpose of the Study:

• To compare the accuracy and repeatability of central corneal thickness (CCT) measurements using swept-source anterior segment optical coherence tomography (AS-OCT), spectral-domain retinal OCT with a corneal module, and ultrasound pachymetry (USP).
• To assess the repeatability of pachymetric mapping provided by AS-OCT.

Main Methods:

• Fifty healthy volunteers underwent repeated CCT measurements using AS-OCT, retinal OCT, and USP by a single operator.
• Statistical analyses included repeated-measures ANOVA, Bonferroni tests, Pearson correlation, and Bland-Altman plots.
• Repeatability was evaluated using Cronbach's Alpha, intraclass correlation coefficient (ICC), and coefficient of repeatability.

Main Results:

• Mean CCT values were 540±28.9 μm (AS-OCT), 544±29.5 μm (retinal OCT), and 549.3±31.7 μm (USP), with statistically significant differences (p<0.01).
• All three instruments demonstrated high correlation in CCT measurements (r > 0.96).
• AS-OCT exhibited significantly higher repeatability for CCT measurements (p<0.001) and excellent repeatability for pachymetric maps (ICC=0.999).

Conclusions:

• Swept-source AS-OCT provides highly repeatable central corneal thickness (CCT) measurements and excellent repeatability for pachymetric mapping.
• While AS-OCT, retinal OCT, and USP measurements are highly correlated, they are not identical.
• AS-OCT demonstrates superior repeatability compared to the other assessed methods.