Exploring the links between contact lens comfort, osmolarity and lid wiper staining.

PURPOSE

Contact lens discomfort remains poorly understood, not least due to lack of associations between clinical signs and symptoms. This study aimed to explore the relationships between osmolarity, comfort and lid wiper epitheliopathy in contact lens wear.

METHODS

Twenty subjects participated in a randomized, cross-over study where comfilcon A and lotrafilcon A lenses were each worn for 10days separated by a 7days washout period. Tear and contact lens osmolarity, ocular symptoms including comfort, tear stability and production, and lid wiper epitheliopathy were measured.

RESULTS

Comfort and tear stability decreased and upper lid wiper staining and foreign body sensation increased with lens wear. These were not affected by lens type. A reduction in tear production was seen after 10days of comfilcon A lens wear. High proportions of lid wiper epitheliopathy were observed at the upper (range 65%-85%) and lower (range 90%-100%) lid margins. Tear and contact lens osmolarity were unaffected by lens wear or type. Contact lens osmolarity was associated with comfort (r=0.45, p=0.009). Tear osmolarity moderately correlated with tear stability (r=-0.53, p=0.014) and tear production (r=-0.44, p=0.012) but not with lid wiper staining.

CONCLUSIONS

A relationship between comfort and contact lens osmolarity and between tear osmolarity and tear stability and production were found, however, this study was unable to demonstrate an association between comfort and tear osmolarity or lid wiper epitheliopathy. Further studies using contact lenses with a wider range of comfort responses are warranted to investigate these associations further.