Correlation between corneal sensitivity, subjective dry eye symptoms and corneal staining in Sjogren's syndrome

Background: Previous studies have shown a poor correlation between dry eye symptoms and objective clinical signs in patients with Sjogren's syndrome. We examined the hypothesis that reduced corneal sensitivity is associated with increased ocular surface disease and reduced symptoms in patients with Sjogren's syndrome. Methods: Eighteen subjects with a diagnosis of Sjogren's syndrome attending a Sjogren's clinic participated in the study. All participants completed the Ocular Surface Disease Index (OSDI) and the Symptom Severity of Discomfort (SSD) scale and answered a question regarding overall severity of dry eye symptoms. The subjects underwent measurement of best-corrected Snellen visual acuity, corneal sensitivity testing with the Cochet-Bonnet esthesiometer, fluorescein and lissamine green staining of the cornea, Schirmer's test I and determination of the tear film break-up time. The results were analysed using Pearson correlational analysis. Results: Both fluorescein and lissamine green staining of the cornea correlated negatively with central corneal sensation (r = -0.3542, p = 0.034, and r = -0.3748, p = 0.029 respectively), indicating that corneal sensation was reduced with increased ocular surface disease. The overall symptom severity correlated negatively with lissamine green staining of the cornea (r = -0.4310, p = 0.011), suggesting reduced symptoms with increased corneal disease. Interpretation: Reduced corneal sensation correlated with increased ocular surface disease. Ocular surface disease similarly demonstrated a reciprocal relation with patients' dry eye symptoms. Consequently, we found that patients with Sjogren's syndrome with advanced corneal staining tended to have fewer dry eye symptoms than patients with less corneal staining.