Microstructural quantification of changes in LSCD may improve disease monitoring
MedWire News: Researchers have characterized significant microstructural changes associated with early limbal stem cell deficiency (LSCD), which could help understand, classify, and monitor the disease process.
Sophie Deng (Jules Stein Eye Institute, Los Angeles, USA) says the findings "could also serve as a useful foundation for the development of a non-invasive method to quantify and monitor the progression of LSCD and response to treatment."
For the study, 27 eyes of 20 patients with LSCD and 12 eyes from 10 healthy controls underwent slitlamp examination, and LSCD was classified as early, intermediate, or late stage on the basis of clinical presentation.
The researchers then performed confocal microscopy of the central cornea and four locations of the limbus. In addition, morphologic characteristics of the corneal epithelium, basal epithelial cell density, and sub-basal nerve density in the central cornea were investigated.
Analysis of morphologic changes in the corneas of patients with LSCD showed that the wing layer was affected in 50% of patients, with nuclei becoming hyper-reflective and visible at the more superficial layer in early LSCD. In addition, basal cell size became progressively metaplastic.
Compared with healthy controls, patients with early-stage LSCD had an average 38% reduction in basal cell density (BCD) and a 58% reduction in sub-basal nerve density(SND). "A decrease in BCD is expected as a result of the failure of stem cell function; however, loss of innervations is a surprising finding in LSCD," say the authors.
With more advanced disease, these changes were more prominent and epithelial cells at all levels were affected. Epithelial cells in the late stage showed significant metaplasia, and normal morphology of basal and wing epithelial cells was lost. In addition, all sub-basal nerves were lost in patients with late-stage LSCD.
Assessment of BCD and SND in patients with LSCD and healthy controls revealed that the decrease in BCD was significantly correlated with the decrease in SND only among patients with LSCD.
The researchers also found that using a cutoff value for BCD of 7930 cells/mm2 gave a sensitivity and specificity o 95.5% and 100%, respectively. For SND, the lower cutoff was calculated at 53 nerves/mm2, with associated sensitivity and specificity of 87.0% and 91.7%, respectively.
"On the basis of these results, a decrease in the BCD of more than 15.4% and a decrease in the SND of more than 47.7% might be associated with the earliest signs of limbal stem cell dysfunction," say the researchers.
The findings are published in the Archives of Ophthalmology.
By Ingrid Grasmo