Limbal stem cell deficiency (LSCD) is an ocular surface disorder that results from decreases in the number and function of corneal epithelial stem and progenitor cells that results in the inability to maintain the normal homeostasis of the corneal epithelium.
LSCD signs include conjunctivalization and persistent epithelial defects with or without neovascularization, ocular surface inflammation, and scarring. The disease can be acquired non-immune-mediated, acquired primary immune-mediated, idiopathic, or inherited.
Diagnosis can be tricky because the disease presentation varies greatly with the degrees of severity of the stem cell deficiency, according to Sophie X. Deng, MD, PhD. This can range from stippling staining in the very early stage to a vortex configuration in the late stage with loss of the palisades of Vogt and vortex keratopathy.
A problem with LSCD is the difficulty in differentiating it from severe dry eye disease, according to Dr. Deng, professor, Stein Eye Institute, University of California, Los Angeles. LSCD can present with staining patterns not generally associated with the disease.
Physicians have used impression cytology to detect corneal goblet cells in LSCD, but the sensitivity of the technique is too low to establish a definitive diagnosis and the degree of the stem cell deficiency cannot be quantified.
Confocal microscopy using the Heidelberg Retina Tomograph III (HRT) is a more reliable and rapid way to diagnose LSCD that visualizes all of the corneal microstructures from the epithelium to the endothelium, Dr. Deng explained.
“In vivo imaging using the HRT III has very high resolution, which facilitates visualization of individual cells, the nerve plexus, the conjunctiva/cornea junction, and the palisades of Vogt,” she said.
The goal of microscopy is detection of the changes in the cell morphology that are evident even in early-stage disease. Dr. Deng demonstrated that the corneal cells appear to enlarge with disease progression and become more metaplastic followed subsequently by the absence of stem cells altogether in the corneal epithelium. In the limbus, some eyes exhibit an influx of inflammatory cells.