Abstract
Purpose :
For assessing corneal biomechanics, resolving spatial heterogeneity both in depth and over a wide lateral field of view is advantageous to observe the effects of crosslinking procedures and diseases such as keratoconus – both of which vary as a function of corneal depth and lateral position. Phase decorrelation optical coherence tomography (PhD-OCT) is able to resolve the varying depth-dependent effects of different corneal crosslinking protocols and, through the use of a conical scanner, an improved ability to scan a wide field of view.
Methods :
Ex vivo porcine corneas were imaged with both a typical telecentric scanner and the conical scan sample arm (following Beer et al., 2017) in conjunction with a 1310nm spectral domain OCT system. M-B scans were acquired and processed to extract the short-time complex decorrelation, as described in prior work (Blackburn et al., 2019). Crosslinking protocols were applied, including the Dresden protocol and accelerated protocols.
Results :
Using the conical scanning system, there is no substantial degradation of image quality in the periphery and thus no corresponding degradation of the decorrelation signal. The preserved signal quality allows for decorrelation analysis further from the central cornea. Differences in the depth-profiles that were observed between varying crosslinking protocols correspond well with theory. The use of supplemental oxygen in accelerated protocols enhanced the crosslinking effect.
Conclusions :
Conical focal plane scanners offer significant advantages for noise-sensitive OCT processing methods such as PhD-OCT to reliably extend their reach into the periphery of the cornea. PhD-OCT is demonstrated to provide depth-dependent information about crosslinking state.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.