Mapping of Corneal Layer Thicknesses With Polarization-Sensitive Optical Coherence Tomography Using a Conical Scan...

Area of Science:

• Ophthalmology
• Biomedical Optics
• Medical Imaging

Background:

• Accurate measurement of corneal layer thickness is crucial for diagnosing and managing various ocular conditions.
• Traditional imaging methods may have limitations in visualizing and quantifying the thickness of individual corneal layers.
• Polarization-sensitive optical coherence tomography (PS-OCT) offers enhanced contrast for microstructural imaging.

Purpose of the Study:

• To demonstrate the segmentation and mapping of corneal layers (epithelium, Bowman's layer, stroma) across the entire cornea using PS-OCT.
• To analyze the reproducibility of PS-OCT for corneal layer thickness measurements.
• To create detailed thickness maps of the cornea from limbus to limbus.

Main Methods:

• Utilized a custom-built PS-OCT system operating at 1045 nm with conical scanning for wide-field imaging.
• Conical scanning ensured near-perpendicular beam incidence for optimal signal quality across the cornea.
• Segmented corneal layers (epithelium, Bowman's layer, stroma) and computed thickness maps in 20 healthy volunteers, with repeated measurements for reproducibility assessment.

Main Results:

• Epithelial thickness maps revealed significant superior thinning and inferior thickening.
• Bowman's layer showed homogeneity centrally, thinning towards the periphery, and disappearing at 4-5.5 mm eccentricity.
• High reproducibility was found for epithelium (CV < 3%), Bowman's layer (CV < 5%), and stroma (CV < 2%) thickness measurements, with significant inter-eye correlation.

Conclusions:

• PS-OCT with conical scanning is a feasible and highly reproducible method for generating large-field corneal thickness maps.
• The technique allows for detailed analysis of individual corneal layer morphology and thickness variations.
• This approach holds promise for enhanced clinical assessment and research in ophthalmology.