Evaluating the Palisades of Vogt in Optical Coherence Tomography Volumes; Enface Segmentation, Scoring and Reporting for Clinical Assessment

Evaluating the Palisades of Vogt in Optical Coherence Tomography Volumes; Enface Segmentation, Scoring and Reporting for Clinical Assessment Kira Lynn Lathrop, PhD University of Pittsburgh, 2024 Normal vision depends on the constant replenishment of the cells that protect the clear surface of the eye. Every time you blink your eyes, you clear away some corneal epithelial cells, which are then replaced by new cells originating from the Palisades of Vogt (POV). Within the fibrovascular ridges of the POV, this lifelong regeneration relies on proper functioning of limbal epithelial stem cells. The goal of this dissertation is to improve our ability to research corneal surface related visual loss by developing a way to visualize, document and report the status of the POV. First, we developed and validated an open-source approach to enface evaluation of the status of the POV from optical coherence tomography (OCT) volumes. The POV are located primarily in the superior and inferior limbus and are defined by fibrovascular ridges in the basement membrane of the epithelium. Providing a consistent method to produce enface images from OCT requires extracting images ranging around the basement membrane of the epithelium rather than using the corneal surface as a reference because different ocular pathologies can change the depth of the epithelium. Second, we developed a rating system referencing OCT volumes acquired from both normal and pathological eyes to describe the configuration of the POV. Changes in the status of the POV in different pathological conditions have been reported, but there is no current scale that characterizes the configuration of the palisades at the level of the basement membrane. Five corneal experts were recruited to validate the rating instrument. Finally, we developed reporting guidelines for documenting the acquisition method of POV volumes for enface imaging. There is no current documentation recommendation, and ambiguous reporting can confound the ability to synthesize results of future clinical trials. Standardizing reporting will facilitate comparability and consistency between research groups.