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

Yuan Tian, Mark Draelos, Ryan P. McNabb, Kris Hauser, Anthony N. Kuo, Joseph A. Izatt

Research output: Contribution to journalArticlepeer-review

Abstract

Optical coherence tomography (OCT) may be useful for guidance of ocular micro-surgeries such as deep anterior lamellar keratoplasty (DALK), a form of corneal transplantation that requires delicate insertion of a needle into the stroma to approximately 90% of the corneal thickness. However, visualization of the true shape of the cornea and the surgical tool during surgery is impaired in raw OCT volumes due to both light refraction at the corneal boundaries, as well as geometrical optical path length distortion due to the group velocity of broadband OCT light in tissue. Therefore, uncorrected B-scans or volumes may not provide an accurate visualization suitable for reliable surgical guidance. In this article, we introduce a method to correct for both refraction and optical path length distortion in 3D in order to reconstruct corrected OCT B-scans in both natural corneas and corneas deformed by needle insertion. We delineate the separate roles of phase and group index in OCT image distortion correction, and introduce a method to estimate the phase index from the group index which is readily measured in samples. Using the measured group index and estimated phase index of human corneas at 1060 nm, we demonstrate quantitatively accurate geometric reconstructions of the true cornea and inserted needle shape during simulated DALK surgeries.

Original languageEnglish (US)
Pages (from-to)5035-5049
Number of pages15
JournalBiomedical Optics Express
Volume13
Issue number9
DOIs
StatePublished - Sep 1 2022
Externally publishedYes

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Biotechnology

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