Fluorophotometric Analysis of the Ocular Surface Glycocalyx in Soft Contact Lens Wearers

Abstract

Purpose: Unstable tear film characterized by shorting of tear break-up time (BUT) is associated with discomfort and dryness in contact lens wearers. The glycocalyx is thought to be crucial in maintaining the wettability and lubrication of the ocular surface. We evaluated the ocular surface glycocalyx in soft contact lens (SCL) wearers using a fluorescein-labeled wheat germ agglutinin (F-WGA) as a marker to demonstrate the ocular surface glycoconjugates in vivo.

Methods: Twenty experienced SCL wearers and 20 healthy volunteers with no history of CL wearing (controls) were enrolled in the study. After applying a 5% F-WGA solution to the eyes of study individuals, fluorescent intensities in their respective central corneas were measured by fluorophotometry. The relationship between F-WGA intensity in the corneal surface and clinical parameters associated with contact lens wear were analyzed.

Results: F-WGA fluorescence intensity in the SCL group was 418.5 ± 103.3, which was significantly lower than that of the controls (825.0 ± 179.8; p < 0.0001, Mann-Whitney test). F-WGA fluorescence intensity was not correlated with Schirmer's test values or age, whereas a statistically significant correlation between F-WGA fluorescence intensity and tear film BUT was observed (r = 0.77, p < 0.0001). The decrease in F-WGA fluorescence intensity could be reversed by discontinuation of SCL use.

Conclusion: Reduction and/or compositional alteration of ocular surface glycocalyx may be one of the causative factors of SCL-induced eye dryness.

Keywords: Contact lens; cornea; fluorescein; lectins; mucins.