Novel Methodology to Create Volumetric Analysis of Limbal Palisades of Vogt Complex on En Face Optical Coherence Tomography for Limbal Stem Cell Deficiency Assessment

Abstract

Purpose : To describe a novel methodology to create volumetric analysis of palisades of Vogt complex (PVC) on en face anterior segment-optical coherence tomography (AS-OCT) and compare healthy eyes and with limbal stem cell deficiency (LSCD).

Methods : En face AS-OCT images of healthy eyes and with stage I and II LSCD were retrospectively exported as multiple 9µm-stacks throughout the limbus thickness (including superior, inferior, temporal and nasal). The limbal hyporeflective structures represent healthy epithelium and palisades, named PVC. The surrounding hyperreflective sclera and Descemet’s membrane from the PVC were reference for tracing each image by 2 graders with ImageJ. Intraclass correlation coefficient (ICC) were performed and the traced area of 1 grader was analyzed. First, image contrast was inverted and binarized with local Otsu threshold. The thresholded PVC areas were stacked in layers to generate a 3-dimensional structure. Imaris software was then used to measure the PVC total surface area and volume. Statistical models were performed for PVC measures to account for age and inclusion of different limbus of same eye. Spearman correlations between clinical severity and PVC measures were performed.

Results : Total 6 eyes of 6 healthy subjects and 7 eyes of 7 LSCD patients were included. There was no significant difference in age (34.2±3.2 and 42.4±13.8 years, respectively;p=0.226) or gender distribution (p=0.592). The ICC between graders was 0.970. Healthy superior and inferior PVC showed greater surface area (8.1mm²) and volume (0.15mm³) compared to nasal and temporal (4.67mm²,p=0.001; and 0.07mm³, p<0.001). Compared to controls, the superior and inferior limbus with LSCD showed significantly lower PVC surface area (4.49mm²,p<0.001) and volume (0.08mm³,p<0.001). Compared to controls, the nasal and temporal limbus with LSCD showed lower PVC surface area (2.87mm², p=0.007) and volume (0.04mm³,p<0.001). Both PVC surface area and volume inversely correlated with clinical LSCD severity (r=-0.763 and r=-0.836, respectively;p<0.01).

Conclusions : A novel image processing methodology can create volumetric PVC measurements on en face AS-OCT that are potentially useful to diagnose LSCD.

This is a 2021 Imaging in the Eye Conference abstract.

 

Figure 1-A) Superficial en face AS-OCT image highlighting the PVC area (yellow line). B) 3-dimensional PVC reconstruction within the highlighted area.