Optical coherence tomography refraction and optical path length correction for image-guided corneal surgery.

Area of Science:

• Ophthalmology
• Biomedical Optics
• Medical Imaging

Background:

• Optical Coherence Tomography (OCT) shows promise for guiding ocular microsurgeries.
• Deep anterior lamellar keratoplasty (DALK) requires precise needle insertion into the corneal stroma.
• Raw OCT data suffers from refraction and optical path length distortion, hindering accurate surgical visualization.

Purpose of the Study:

• To develop a 3D correction method for refraction and optical path length distortion in OCT volumes.
• To enable accurate geometric reconstruction of natural and surgically altered corneas.

Main Methods:

• Introduced a method to correct for both refraction and optical path length distortion in 3D.
• Delineated the roles of phase and group index in OCT image distortion.
• Developed a method to estimate the phase index from the group index.
• Utilized human cornea group and estimated phase indices at 1060 nm.

Main Results:

• Demonstrated quantitatively accurate geometric reconstructions of the true cornea shape.
• Successfully reconstructed the shape of an inserted needle during simulated DALK surgeries.
• Corrected OCT B-scans provided accurate visualization for surgical guidance.

Conclusions:

• The developed method accurately corrects OCT image distortions caused by corneal geometry and needle insertion.
• This technique enhances the reliability of OCT for guiding delicate ocular microsurgeries like DALK.
• Accurate 3D OCT reconstructions are crucial for improving surgical outcomes in corneal transplantation.