2023 Volume 30 Issue 2 Pages 75-81
Eye discomfort due to dryness is one of the major complaints reported in indoor spaces, especially during the winter months when the humidity is low. Although indoor humidity is reported to affect the stability and thickness of the tear film that protects the ocular surface, the relationship between these physiological parameters and the complaints of dryness or discomfort in the eyes remains unclear. As a fundamental study for evaluation of the effect of indoor humidity on complaints of eye discomfort, this paper aimed to clarify the effects of the tear-film condition on eye dryness and discomfort sensations. Physiological and psychological parameters were measured in the eyes of 18 subjects, including 9 SCL (soft contact lens) wearers, under multiple humidity conditions, and correlations and causal relationships among them were analyzed using multi-level model, which can distinguish between inter- and intra-individual effects. The results indicate that intra- and inter-individual variances in multiple tear-film parameters are associated with variances in eye dryness and discomfort. In the naked-eye group, dryness and discomfort sensations were stronger in individuals when the tear film was less stable, while in the SCL-wearing group, these sensations were stronger in individuals when the tear volume on the lens was lower.
