An in vivo confocal masked study on corneal epithelium and subbasal nerves in patients with dry eye

PURPOSE. The objective of the present study was to determine whether dry eye ( DE) associated with primary Sjogren's syndrome (PSDE) and DE not associated with Sjogren's syndrome (NSDE) are related to an alteration of corneal innervation. METHODS. Eleven healthy volunteers younger than 60 years (normal [N] < 60 group), 10 healthy volunteers 60 years of age or older (N >= 60 group), 11 patients with PSDE, and 10 patients with NSDE were studied. Epithelial and stromal density and subbasal and stromal nerves were investigated by confocal microscopy. RESULTS. The density of the superficial epithelial cells was 741 +/- 306 cells/mm(2) in the PSDE group; 1022 +/- 331 cells/mm(2) in the NSDE group; 1523 +/- 294 cells/mm(2) in the N >= 60 group, and 1529 +/- 341 cells/mm(2) in the N < 60 group ( P < 0.0001, ANOVA). The number of subbasal nerves was 2.8 +/- 1.2 in the PSDE group, 3.3 +/- 0.7 in the NSDE group, 3.1 +/- 0.9 in the N >= 60 group, and 4.6 +/- 0.8 in the N < 60 group (P < 0.0001, ANOVA). The number of beadlike formations observed in the different groups was 387 +/- 62/mm in the PSDE group, 323 +/- 64/mm in the NSDE group, 182 +/- 63/mm in the N >= 60 group, and 198 +/- 66/mm in the N < 60 group (P < 0.0001, ANOVA). A correlation was found between the number of subbasal nerves and age (P < 0.01) and between the number of subbasal nerves and Schirmer's test (P < 0.001, Spearman rho). CONCLUSIONS. Patients with DE show alteration in the corneal innervations. The demonstration of such alterations introduces new strategies for treatment of this frequent disease.