Corneal sensitivity in dry eye: a longitudinal pilot study

Background Dry eye is a highly prevalent, multifactorial disease, whose management is extraordinarily challenging. Despite numerous research studies, its detailed pathogenesis remains unclear. Impaired corneal sensitivity is a major contributor to the etiology of dry eye. Understanding the relationship between corneal sensitivity and both etiology and severity of the disease may further aid the treatment of dry eye syndrome and ocular surface diseases. The current survey therefore aims to observe corneal sensitivity in dry eye subjects longitudinally, as well as the correlation between corneal sensitivity and different parameters of dry eye syndromes. Material and methods In this prospective, non-randomized, single-arm, observational study, 28 patients with dry eye were examined on four occasions at regular intervals over a period of 3 months. Corneal sensitivity was measured with cochet-bonnet esthesiometer. Tearfilm and ocular surface were explored by schirmer (I) test, break-up-time, corneal staining (fluorescein, lissamine green) and lipid interference. Etiology, disease progression and treatment were recorded by using specific protocols. Patients were classified in subgroups (hormonal, immune, neural, toxic, environmental). Corneal sensitivity and different parameters of dry eye were correlated using Pearson's-correlation. Welch's test was used to compare corneal sensitivity in non-nerve induced versus nerve induced etiological subgroups. Results Means of corneal sensitivity over three months were 4.89, 4.93, 4.91 and 5.08 mm. Serial data curves of corneal sensitivity demonstrated pronounced variability of values, both inter-and intraindividually. A negative correlation was seen between corneal sensitivity and sicca-score (R -0.37). No relationship was observed between schirmer test and corneal sensitivity. Highest corneal sensitivity values were found in the environmental etiological group (5.39). T-test analysis of corneal sensitivity and etiology (non-nerve induced versus nerve induced) was not significant (p = 0.76). Conclusion Results indicate a high variability of corneal sensitivity interindividually as well as intraindividually. This supports the hypothesis of different states of compensation during the continuum of the disease.