Abstract
Purpose: :
To investigate the relationship between conjunctival and corneal sensitivity and the severity of dry eye symptoms assessed using four commonly–used dry eye questionnaires.
Methods: :
97 healthy subjects (66 females and 31 males, aged 19 to 79 years) were recruited and completed the study. 64 of the subjects who completed each of the questionnaire in their entirety were included in the analysis. The Ocular Surface Disease Index© (OSDI), the McMonnies Questionnaire (McM), the Indiana Dry Eye Questionnaire (DEQ) and the Subjective Evaluation of Symptoms of Dryness (SESOD) were used to assess symptom severity. Conjunctival and corneal thresholds were measured on the right eye only of each subject, using a computer–controlled pneumatic esthesiometer with stimulus temperature set at 20°C. Factor Analysis was used to generate factor scores for the DEQ and symptom scores of the other three dry eye questionnaires were calculated according to their own scoring system. Spearman Rank Order correlations and Wilcoxon Matched Pair tests were used for data analysis.
Results: :
The scores of all four dry eye questionnaires were correlated (Rho ranged from 0.6 to 0.8, all p<0.05). Conjunctival threshold was significantly correlated to the scores of all dry eye questionnaires (Rho –0.3 to –0.5, all p<0.05) while corneal threshold was correlated to the scores of McM, SESOD and DEQ main factor scores (Rho –0.3 to –0.4, p<0.05) but not to the OSDI item score. Coefficients of correlation between symptom scores and conjunctival threshold were greater than those with corneal threshold (p=0.03).
Conclusions: :
Subjects who showed conjunctival and corneal hypersensitivity tended to have higher scores of dry eye symptoms. Conjunctival sensitivity may be an index of the altered neural processing of the ocular surface and the resultant sensations related to dry eye symptoms.
Keywords: conjunctiva • cornea: clinical science • cornea: tears/tear film/dry eye