Conjunctival surface changes in patients with Sjogren's syndrome: A transmission electron microscopy study

PURPOSE. To demonstrate the ultrastructural appearance of the conjunctival surface epithelium in patients with Sjogren'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 mu m 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 mu m) 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 mu m, 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 mu m 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.