Evaluation of the relationship between dry eye syndrome severity and corneal sensitivity.

PURPOSE: This study aimed to evaluate the relationship between the objective severity of dry eye disease subjective symptoms, and corneal sensitivity.

METHODS

The study included 62 eyes from 31 healthy volunteers and 150 eyes from 75 patients diagnosed with dry eye disease . Participants underwent the Schirmer I test, tear break-up time assessment, and corneal staining evaluation using the Oxford Scale. Subjective symptoms were assessed through the Ocular Surface Disease Index questionnaire and a modified Ocular Surface Pain Score questionnaire. Corneal sensitivity was measured in five corneal regions using a Cochet-Bonnet esthesiometer. Dry eye disease severity was graded from 1 to 5 based on the Oxford Scale. Comparative analyses were performed.

RESULTS

Schirmer I and tear break-up time values were significantly lower in the DED group, while Ocular Surface Disease Index and Ocular Surface Pain Score were significantly higher (p<0.001 for all). Corneal sensitivity in all quadrants was significantly lower in DED patients (p<0.001 for all). A strong correlation was observed between the Ocular Surface Pain Score and the Ocular Surface Disease Index (r=0.983, p<0.001). Central corneal sensitivity exhibited a moderate positive correlation with Schirmer I and tear break-up time (p<0.001, r=0.583 and 0.657, respectively) and a moderate negative correlation with Ocular Surface Disease Index and Ocular Surface Pain Score (p<0.001, r=0.625 and -0.631, respectively). Disease severity progression was associated with increased Ocular Surface Disease Index and Ocular Surface Pain Score, but no statistically significant difference was found between Grades 3 and 5. Similarly, corneal sensitivity decreased with advancing disease severity, yet no significant difference was observed between Grades 4 and 5.

CONCLUSION

Corneal sensitivity decreases in dry eye disease and is negatively correlated with disease severity. Subjective symptoms increase with disease progression and show a positive correlation with severity. The absence of significant differences between the advanced stages suggests that neuropathic mechanisms and subbasal nerve plexus deterioration play a role in chronic and late-stage dry eye disease.