Abstract
Purpose :
Dry-eye is a debilitating condition of the ocular surface. One of the therapies of dry-eye is the use of essential fatty acids (EFAs) which reduce the inflammation and symptoms in dry-eye patients. EFAs are mainly given by dietary supplementation. Recently, eye drops containing EFAs have been developed and are being investigated. EFAs applied topically to the ocular surface might interact with the lipid layer of the tear film and affect its integrity. Therefore, the aim of this study was to investigate the biophysical interactions of EFAs with meibomian lipids at an air-tear interface.
Methods :
Human meibomian lipids were spread on an artificial tear solution in a Langmuir trough maintained at 35°C. The lipids film at the air-tear interface was compressed and expanded to record pressure-area isocycles. Human meibomian lipids were mixed with EFAs (linoleic acid and α-linolenic acid) in different mole fraction ratios and their interactions were studied by recording pressure-area isocycles of the mixed films.
Results :
Linoleic acid added to meibomian lipids film increased its lift-off area and the maximum surface pressure at the highest compression. At 0.2 mole fraction, it increased the lift-off area from 30 to 34 Å2, and maximum surface pressure from 14 to 23 mN/m. Increasing amounts of the fatty acid further increased lift-off area and maximum pressure till 0.6 mole fraction (40 Å2, 34 mN/m) after which there was no further increase. α-Linolenic acid showed a different effect on meibomian lipids. At 0.2 mole fraction, it decreased the lift-off area from 30 to 24 Å2, and maximum surface pressure from 14 to 12 mN/m. Increasing amounts of the fatty acid further decreased lift-off area (17 Å2 at 0.8 mole fraction) but there was no further decrease in the maximum surface pressure.
Conclusions :
EFAs added topically to the ocular surface are likely to interact with the lipid layer of the tear film and affect its biophysical function. Linoleic acid expands meibomian lipids film and makes it exert more surface pressure which can be beneficial for tear stability. α-Linolenic acid condenses meibomian lipids film with less surface pressure which may not be beneficial for tear stability. Further studies supplemented with clinical evaluations of ocular surface parameters will be needed to determine the benefits of topical application of EFAs for dry-eye.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.