Quantitative OCT-based corneal topography in keratoconus with intracorneal ring segments

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Medical Imaging

Background:

• Keratoconus is a progressive corneal ectasia leading to irregular astigmatism and vision loss.
• Intracorneal ring segments (ICRS) are used to reshape the cornea and improve visual acuity in keratoconus patients.
• Accurate 3-D characterization of corneal topography and ICRS is crucial for treatment assessment.

Purpose of the Study:

• To develop and validate custom high-resolution, high-speed anterior segment spectral domain Optical Coherence Tomography (sOCT) protocols for 3-D corneal topography analysis.
• To create custom algorithms for automatic detection, classification, and 3-D positioning of implanted ICRS.
• To quantitatively assess the pre- and post-operative effects of ICRS implantation on corneal topography and pachymetry in keratoconus.

Main Methods:

• Utilized custom high-resolution, high-speed anterior segment sOCT with corrected scanning and optical distortions.
• Developed custom algorithms for automatic detection and classification of anterior segment volumes, including ICRS.
• Employed quantitative analysis of corneal elevation maps and pachymetry, fitted with biconicoids and Zernike polynomials.
• Estimated 3-D ICRS positioning and pupil center reference from segmented iris volume.

Main Results:

• ICRS implantation resulted in anterior corneal surface flattening and posterior surface steepening.
• Observed meridional differences in curvature and asphericity changes, with increased anterior topography symmetry.
• Accurate pachymetric estimates revealed increased thickness in ectatic and peripheral corneal areas.
• Automatic tools successfully estimated ICRS depth and rotation relative to the pupil plane.

Conclusions:

• Anterior segment sOCT, with distortion correction and analysis tools, is highly effective for evaluating and monitoring keratoconus.
• This method provides quantitative assessment of corneal changes induced by ICRS treatment.
• The developed algorithms enable precise characterization of ICRS positioning and its impact on corneal biomechanics.