Insights into atypical segmental layer thicknesses and phase retardation in thick corneas using ultrahigh-resolution polarization-sensitive optical coherence tomography

Accurately assessing corneal structural status is challenging when thickness deviates from the average. Polarization-sensitive optical coherence tomography (PS-OCT) measures tissue-specific polarization changes, providing additional contrast for accurate segmentations and aids in phase retardation (...

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Bibliographic Details
Published in:Eye and vision (Novato, Calif.) Calif.), 2024-07, Vol.11 (1), p.30-8, Article 30
Main Authors: Patil, Rahul P, Shetty, Rohit, Khamar, Pooja, Patel, Yash G, Narasimhan, Raghav R, Bhatkal, Anushree A, Hitzenberger, Christopher K, Pircher, Michael, Nuijts, Rudy M M R, Sinha Roy, Abhijit
Format: Article
Language:English
Subjects:
Analysis
Biomechanics
Care and treatment
Coherence (Optics)
Collagen
Diagnosis
Eye diseases
Keratoconus
Optical tomography
Phase retardation
PS-OCT
Stroma
Thick cornea
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Summary:Accurately assessing corneal structural status is challenging when thickness deviates from the average. Polarization-sensitive optical coherence tomography (PS-OCT) measures tissue-specific polarization changes, providing additional contrast for accurate segmentations and aids in phase retardation (PR) measurements. Previous studies have shown PR's effectiveness in identifying sub-clinical keratoconus (KC) in asymmetric cases. Thus, this study aims to assess PR distribution in thick corneas with and without KC. In this retrospective and cross-sectional study, 45 thick corneas from 30 Asian-Indian subjects, categorized into healthy (n = 26) and KC (n = 19) groups were analyzed. All eyes underwent standard clinical evaluations, tomographic assessments, and corneal biomechanics measurements. PR and individual layer thicknesses were measured using custom-designed ultrahigh-resolution PS-OCT. PR en-face maps were generated. Individual layer thicknesses and PR analysis was conducted across multiple zones, extending up to 8-10 mm in diameter. All eyes in the study had not undergone interventions, received topical medications, or had previous corneal disease history. Significant differences were found in spherical and cylindrical powers, keratometry, pachymetry, and biomechanical indices (all P 
ISSN:2326-0254
2326-0254
DOI:10.1186/s40662-024-00391-4