In Vivo Laser Confocal Microscopic Findings of Palisades of Vogt in Normal Subjects and Patients with Ocular Surface Disease

Abstract

Purpose: : To determine the structural appearance of palisades of Vogt in normal subjects and patients with ocular surface disease (OSD) using in vivo laser confocal microscopy (IVCM).

Methods: : IVCM (HRT3/RCM, Heidelberg Engineering) was performed in 10 normal eyes and 4 eyes with clinically confirmed OSD in the superior and/or inferior limbus. Detailed structural features of palisades of Vogt were compared between inferior and superior limbus of normal subjects and patients. Images were quantified for hyper-reflective epithelioid cells and analyzed for presence and morphology of immune cells.

Results: : IVCM demonstrated significant cellular and structural differences between the normal inferior and superior palisades. Inferior palisades appeared as parallel, 75 μm wide, elongated structures, separated by 6-10 rows of limbal epithelial cells. Central hyper-reflective fibroconnective tissue was present, surrounded by a combination of a thin layer of minimally reflective epithelium with scattered dense intracellular hyper-reflectivity (ICH). In contrast, superior palisades appeared as round or oval 65 μm wide structures. Scattered limbal epithelial cells surrounded the central fibroconnective tissue. The mean density of ICH differed between superior and inferior palisades (2.7/200 vs. 6/200 μm length of palisades). No immune cells were detected in normal subjects. In contrast, patients with OSD demonstrated a significant increase in ICH in superior and inferior palisades (14/200 vs. 16.6/200 μm; p<0.001). Considerable infiltration of immune cells in the areas of palisades was present in 50% of eyes with OSD.

Conclusions: : IVCM demonstrates significant differences between superior and inferior palisades. The presence of ICH in the area of palisades may represent activated nuclei of proliferative limbal epithelial or stem cells. IVCM may serve as a diagnostic tool for assessment of limbal stem cells in patients with clinical suspicion of limbal stem cell deficiency (LSCD). Moreover, the presence of immune cells in the area of limbal palisades suggests a potential role of inflammation in LSCD. Additional studies are required to compare IVCM findings with ocular impression cytology to determine the sensitivity and specificity of IVCM.

Keywords: microscopy: confocal/tunneling • cornea: clinical science • imaging/image analysis: clinical