Liposomal spray may ease contact lens discomfort
By Kathryn Doyle Contact lens wearers with “dry eye” and discomfort may find relief from sprays or drops that add lipids back to the eye, Australian researchers say. They found that among contact lens wearers with the bothersome symptoms, the outermost layer of tears on the eye, a protective layer of lipids, is more degraded than among people without the symptoms. The liposomal spray used in the study is already available on the market, as are similar compounds in drop form, senior author Fiona Stapleton told Reuters Health by phone. “Comfort is really the holy grail both for practitioners who fit contact lenses and people who wear them,” said Stapleton, a practicing clinician and researcher at the School of Optometry and Vision Science at the University of New South Wales in Sydney. Almost half of new contact lens users give up due to discomfort, she said. For the new study, Stapleton and her co-authors tested 10 contact lens wearers who reported discomfort and 10 who did not. The researchers measured how quickly the surface of the participants’ eyes dried out after six hours of lens wear and the quality of the lipid layer of tears by both observation and lab testing tear samples. For the group with discomfort, the eyes took an average of less than five seconds to dry out when refraining from blinking, compared to almost 10 seconds for the group with no discomfort symptoms. Researchers then gave the symptomatic participants a phospholipid spray called Tears Again, distributed by Melbourne-based BioRevive and marketed for dry-eye relief. A 100-dose bottle is available online from the distributor for $20. They compared the time it took for eyes to become dry two and six hours after using the phospholipid spray with the same measures after using a saline spray for comparison. The drying time became shorter more quickly after the saline spray than after the liposomal spray, the authors report in Optometry and Vision Science. The liposomal spray may act to help preserve the lipid layer of tears, Stapleton said. “Imagine an oily layer on the surface of water: it prevents evaporation,” she said. “People who don’t have a sufficient lipid layer have dry eye.” The researchers aren’t sure at this point exactly how the spray helped to maintain the lipid layer. “The main question is - does the lens feel the same on the eye during wear as it feels right after it is first placed on the eye,” said Mark E. Byrne, of the Biomedical Engineering department at Rowan University in Glassboro, New Jersey. “The field is working on these issues from surface chemistry changes to the lens, to molecules in the contact lens solution, to molecules within the lens and released from the lens during wear - all to promote comfort,” said Byrne, who was not part of the new study. Phospholipid sprays may stabilize the lipid layer and help maintain the tear film, he told Reuters Health by email. “Understanding the mechanism will help better products be designed,” Stapleton said. These results are preliminary but exciting, and other available products may help in the same way, she said. “I think different things are going to work for different people,” she said. SOURCE: http://bit.ly/1HFUXus Optometry and Vision Science, online November 20, 2014.
