Clinical and cytological findings in limbal stem cell deficiency
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To evaluate and relate the clinical (including corneal sensitivity and tear function) and cytological (presence of goblet cells and cytokeratin 3- and 19-positive cells) features of limbal stem cell deficiency (LSCD).
Twenty-nine patients (44 eyes) with a clinical diagnosis of LSCD participated in this study. Corneal signs (epithelial alterations, superficial neovascularisation and stromal scarring) and cytological findings (presence of goblet cells and cytokeratins 3 and 19) were evaluated and scored (from 0 to 3) from each of the five corneal sectors. Corneal sensitivity (Cochet-Bonnet aesthesiometer) and tear function (Schirmer test and BUT) were also assessed. Cytological scores were correlated statistically with both corneal signs and sensitivity values.
Cytokeratin 19-positive cells were found in 82% of corneal impression cytology samples, while goblet cells were identified in only 59% of these same samples. Cytokeratin 3-positive cells were present in 61% of LSCD eyes and in all unaffected eyes. Corneal sensitivity was significantly decreased in affected eyes compared with contralateral, healthy eyes (1.6±1.7 cm versus 5.7±0.3 cm). Tear function tests did not show significant changes. In LSCD eyes, goblet cells and cytokeratin 19-positive cells on the corneal surface were significantly correlated to corneal epithelial alterations and to corneal superficial neovascularisation (p<0.001). Corneal cytokeratin 3-positive cells were inversely related to epithelial alterations (p=0.003). Corneal sensitivity was decreased in corneal sectors with epithelial alterations (p<0.001), neovascularisation (p<0.001) and stromal abnormalities (p=0.049), and was indirectly related to the presence of goblet cells (p=0.005) and cytokeratin 19-positive cells (p<0.001).
This study confirmed the importance of cytological tests in the diagnosis of LSCD. Furthermore, the absence of goblet cells may not exclude corneal conjunctivalisation as demonstrated by cytokeratin 19 immunostaining. Lastly, corneal conjunctivalisation was associated with zone-specific impairment in corneal sensitivity.