Fluctuations of Corneal Sensitivity in Dry Eye Syndromes--A Longitudinal Pilot Study

The aim of this study was to observe corneal sensitivity (CoS) longitudinally in patients with dry eye and to evaluate the correlation between CoS, severity, and the etiology of dry eye syndrome (DES).

In this prospective study, 46 patients with DES were examined on 4 occasions within 3 months. CoS was measured by the Cochet-Bonnet esthesiometer. Tear films were evaluated for lipid layer thickness, breakup time, fluorescein and lissamine green staining, and Schirmer test. Patients were classified into etiologic subgroups: hormonal, immunologic, toxic, neural, and environmental. For statistical statistics, Mann-Whitney and Kruskal-Wallis tests were used.

Serial data curves of CoS demonstrated pronounced variability of values. CoS and SICCA scores were negatively correlated (r = -0.454, P = 0.007). The Schirmer test and CoS were positively correlated (r = 0.363, P = 0.013). The environmental group had the highest CoS values (5.5). There was no significant difference in CoS neither between nerve-induced and nonnerve-induced DES groups (P = 0.858) nor within the subgroups (P = 0.118). During 3 months, CoS increased in all patients (4.8-5.1). The DES severity was negatively correlated with CoS, indicating a reduction of neural function in severe DES.

Our results showed diminished CoS in severe dry eye although there was a high variability of CoS. This supports the hypothesis of different states of compensation as the disease continues and an association of CoS with different causes of dry eye. However, no statistical differences were found between etiological subgroups.