RESUMEN
PURPOSE: To demonstrate the ultrastructural appearance of the conjunctival surface epithelium in patients with Sjögren's syndrome (SS) compared with normal subjects. METHODS: Conjunctival tissue specimens from seven normal subjects and eight patients with SS were obtained by bulbar conjunctival biopsy and examined by transmission electron microscopy. RESULTS: The average number of microvilli per 8.3 microm epithelial length was significantly lower in the SS group than that in the control group (19.6 +/- 2.5 vs. 28.0 +/- 3.4, P < 0.0001). The microvillus height (0.539 +/- 0.151 microm) and height-width ratio (1.825 +/- 0.549) in the conjunctival epithelium in the SS group were significantly lower than those (height: 0.946 +/- 0.117 microm, P < 0.001; and height-width ratio: 3.717 +/- 0.696, P < 0.0001) in normal individuals. The microvilli in the SS group were wider than those in the control group (P = 0.003). Furthermore, the average number of secretory vesicles (per 8.3 microm epithelial length) in the apical conjunctival epithelial cell was significantly reduced in the SS group (16.4 +/- 6.8 vesicles), compared with the control group (34.7 +/- 1.2 vesicles, P = 0.003). In addition, although the ocular surface glycocalyx (OSG) was always present in control subjects, it was not detectable in all but one of the SS conjunctival specimens. CONCLUSIONS: The ultrastructural morphology of the apical conjunctival epithelium is altered in patients with SS. The findings suggest that an intact OSG may play a key role in the maintenance of a healthy ocular surface, possibly by preventing abrasive influences on the apical epithelial cells.