# The Potential Lubricating Mechanism of Alginate Acid and Carrageenan on the Inner Surface of Orthokeratology Lenses

## TL;DR

This study explores how alginate acid and carrageenan can reduce friction on orthokeratology lenses by interacting with tear film proteins.

## Contribution

The study identifies electrostatic interactions and complex formation as novel mechanisms for polysaccharide lubrication on ortho-k lenses.

## Key findings

- Tear film proteins increased the friction coefficient of ortho-k lenses.
- Alginate acid and carrageenan significantly reduced friction through electrostatic interactions and complex formation.
- These polysaccharides show potential for reducing friction-related complications in ortho-k lens wearers.

## Abstract

When an orthokeratology (ortho-k) lens contacts the ocular surface, tear film components such as lipids and proteins rapidly adsorb onto the lens, which may increase friction and contribute to discomfort if not properly removed. Polysaccharides have been reported to reduce protein deposition and improve lubrication, prompting the investigation of alginate acid and lambda-carrageenan in modulating the tribological properties of ortho-k lenses. An in vitro tribological property analysis of ortho-k lenses and protein adsorption and desorption analyses were carried out to investigate the lubricating ability of alginate acid and carrageenan. Zeta potential and turbidity analyses were further conducted to examine potential interactions between polysaccharides and tear film proteins. Tear film proteins significantly increased the friction coefficient of the ortho-k lens, whereas the addition of alginate acid and carrageenan markedly reduced friction. Electrostatic interaction and polysaccharide–protein complex formation were identified as possible mechanisms underlying these effects. These results demonstrate that alginate acid and carrageenan can modify the tribological and interfacial behavior of ortho-k lenses in protein-rich environments, suggesting their potential application in reducing friction-related complications in ortho-k lens wearers.