Abstract
Purpose: :
To assess the correlation between corneal epitheliopathy, tear osmolarity and ocular symptoms in a chronic dry eye population.
Methods: :
Patients with different demographic characteristics were asked to fill out two different questionnaires to evaluate dry eye symptoms, the commonly used OSDI (Ocular Surface Disease Index®, Allergan) with 12 specific questions, and SANDE (Symptom Assessment in Dry Eye) based on two questions that assess both severity and frequency of symptoms using a visual analog scale. Corneal epitheliopathy was assessed by fluorescein staining using the Oxford scheme. Tear osmolarity was assessed from both eyes using the TearLab® system. Since both questionnaires approach the patient as a unit, the analysis of the corneal epitheliopathy variable was based on mean corneal staining of the two eyes or based on the most affected eye. We also evaluated the tear osmolarity correlation between two eyes in two subsets of patients: those with mild-moderate (Oxford score ≤ 1.5) and those with severe disease (Oxford scores > 1.5).
Results: :
A total of 282 patient-visits were included in the analysis. There was a strong correlation between measured symptoms using the two questionnaires (R=0.65). Correlation between signs and symptoms was low regardless of the method used to assess epitheliopathy: average of both eyes (R=0.12 for OSDI and R=0.13 for SANDE) or the most affected eye (R=0.14 for OSDI and R=0.12 for SANDE). We found higher tear osmolarity correlation between the two eyes of each subject in patients with severe signs (R=0.533) than in those with mild disease (R=0.279). Similarly patients with mild symptoms (OSDI ≤ 50) had lower tear osmolarity correlation between both eyes (R=0.231) than those with severe symptoms (OSDI > 50) (R=0.570).
Conclusions: :
There is a strong correlation between the OSDI and SANDE questionnaires. Corneal epitheliopathy can only account for part of the symptomatology in dry eye disease. The coefficient of correlation of tear osmolarity between the two eyes of a patient could be predictive of the severity of dry eye disease.
Keywords: cornea: tears/tear film/dry eye • cornea: clinical science • cornea: epithelium