Researchers report the structure of a key long-chain lipid in the tear film lipid layer, which prevents tears from drying out. Their finding may be used to improve treatments for dry eye.

The outer lipid layer, which is itself formed of two sublayers, prevents water evaporation from the liquid layer. Dry eye disease develops when the glands that produce these lipids dysfunction.

Currently available lipid-based eye drops mimic aqueous and lipid layers of the tear film, using mineral oil, castor oil, phospholipids, omega-3 fatty acids and triglycerides.

Very long-chain lipids in the most superficial layer of the tear film cause severe dry eye disease when they were shortened in mice -- a result that could help develop new drugs for the disease.

The outer lipid layer, which is itself formed of two sublayers, prevents water evaporation from the liquid layer. Dry eye disease develops when the glands that produce these lipids dysfunction.