Corneal densitometry measurements comparison between anterior segment OCT and scheimpflug imaging

Area of Science:

• Ophthalmology
• Corneal Imaging
• Biomedical Optics

Background:

• Corneal densitometry (CD) is crucial for assessing corneal transparency.
• Comparing measurement repeatability and agreement between different imaging devices is essential for clinical application.
• Understanding the correlation of CD with demographic factors aids in interpreting results.

Purpose of the Study:

• To compare the repeatability and agreement of corneal densitometry (CD) measurements between an anterior-segment optical coherence tomography (AS-OCT) device (Casia 2) and a Scheimpflug camera system (Pentacam AXL Wave).
• To investigate the correlation of CD with age, gender, and central corneal thickness (CCT) in normal eyes.

Main Methods:

• Corneal densitometry (CD) measurements were acquired using Casia 2 and Pentacam AXL Wave in 96 healthy volunteers.
• Repeatability was assessed via intra-session test-retest variability, coefficient of variation (CoV), and intraclass correlation coefficient (ICC).
• Agreement was evaluated using Bland-Altman plots, and correlation analysis was performed with age, gender, and CCT.

Main Results:

• Casia 2 demonstrated high repeatability (ICC > 0.9) with lower CoV (1.07%-2.25%) compared to Pentacam (1.91%-6.89%) across corneal zones.
• Significant bias was observed between the two devices across all corneal zones.
• Corneal densitometry (CD) values showed a positive correlation with age, except for the central zone (zone 1) with Pentacam.

Conclusions:

• Casia 2 is a reliable tool for assessing corneal transparency in healthy individuals.
• Measurements from Casia 2 and Pentacam are not interchangeable due to observed bias.
• The AS-OCT device may offer greater sensitivity for detecting age-related CD changes in the central cornea.