Abstract
Purpose :
The Palisades of Vogt (POV) are recognized as the corneal epithelial stem cell niche, but identification of this region in ex-vivo tissue is difficult. This study defines a simple, direct method of identifying the POV in ex-vivo human tissue. Using this technique, the POV can be identified prior to harvesting donor tissue for limbal transplant, which may increase the efficacy of this procedure. The anatomical specificity of the POV may also allow them used as a marker to determine the anatomical alignment of donor tissue prior to transplantation. Finally, visualization of this area can assist in procuring good research samples of corneal epithelial stem cells.
Methods :
Eighteen human corneal rims were imaged between crossed circular polarizers from tissue acquired post-transplantation. Radial amber ridges were seen in the limbus in opposing clusters which correspond to the known pattern of palisade ridges. Optical coherence tomography (OCT) volumes were acquired around the circumference of the limbus and were segmented to identify POV regions. To further validate that we were seeing POV, four whole human eyes were obtained and the muscle insertion sites were identified in order to determine the superior/inferior axis of the eye, and the eyes were imaged with OCT. Subsequently, the cornea and limbus were dissected and the tissue was imaged. Radial amber ridges were seen primarily in the inferior and superior axis of the tissue, corresponding to the anatomical location and configuration of the POV.
Results :
Under circularly polarized light the POV presented as amber radial ridges visible in the superior and inferior regions of the tissue. There was excellent correspondence between OCT images of POV and those seen under polarized light.
Conclusions :
Circularly polarized light can be used to quickly identify POV regions in donor tissue which can assist in targeted harvesting of corneal epithelial stem cells and tissue for limbal transplant and for stem cell research. This technique could also allow identification of the alignment axis of the donor tissue when a corneal button is prepared for transplantation.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.