OCT based corneal densitometry: the confounding effect of epithelial speckle

Area of Science:

• Ophthalmology
• Biomedical Optics
• Corneal Imaging

Background:

• Corneal densitometry objectively assesses stromal transparency, with Scheimpflug technology being dominant.
• Optical coherence tomography (OCT) offers an alternative for corneal densitometry by analyzing corneal speckle statistics.
• The influence of the overlying epithelium on in-vivo stromal densitometry measurements using OCT remains unquantified.

Purpose of the Study:

• To quantify the impact of corneal epithelial integrity on OCT-derived stromal densitometry.
• To determine the potential estimation errors introduced by the epithelium in OCT densitometry analysis.

Main Methods:

• Utilized OCT imaging on eleven porcine eyes before and after epithelial debridement.
• Analyzed corneal densitometry at various stromal depths using four distinct speckle statistics metrics.

Main Results:

• Statistically significant differences in speckle statistics were observed based on the presence or absence of the epithelium.
• Estimation errors in stromal densitometry metrics could exceed 20%, varying with stromal depth.
• Anterior stromal densitometry values were most sensitive to changes in epithelial integrity.

Conclusions:

• Epithelial integrity is a critical confounding factor for absolute OCT densitometry measurements of the corneal stroma.
• Accurate stromal densitometry analysis using OCT necessitates accounting for the epithelial layer's influence.