Distichiasis

How it works

The eyelid has one row of lashes along its outer edge. Just behind that row, along the inner rim of the lid, is a line of tiny openings. These are the ducts of the meibomian glands, which make the oily part of the tear film¹. In distichiasis, hairs grow out of those gland openings instead of oil. The result is a second row of lashes behind the first, on the upper lid, the lower lid, or both¹. The extra lashes are often finer and shorter than normal lashes, but they can be full size.

The inherited form is caused by a change in a gene called FOXC2³. This gene helps decide what the cells lining the meibomian ducts become. With the change, some of them become hair follicles. The same gene is important in the lymph vessels, the network that drains fluid from the tissues. For that reason inherited distichiasis is usually part of lymphedema-distichiasis syndrome. The extra lashes are present from birth, and swelling of the legs appears later, often in the teens or twenties⁴.

Distichiasis can also be acquired. Long-term inflammation of the eyelids can push the glands to sprout hairs¹.

No population survey exists. The inherited form is rare and is known mainly from family studies⁴.

Is it a problem?

The lashes themselves are usually fine. If they point inward they can rub the surface of the eye, causing watering, redness, and a gritty feeling¹. An eye doctor can remove or treat the offending hairs. See a doctor if you or your child has a double row of lashes and also swelling of the feet or legs, because that combination points to the lymphedema syndrome and needs assessment⁴. Heart problems are more common in the syndrome, so a heart check is part of that assessment⁴.

History and culture

Elizabeth Taylor was born in 1932 with a double row of dark lashes, later put down to a FOXC2 change². Family accounts say that on an early film set the make-up crew tried to wipe off what they took for mascara². The lashes became part of her famous look. She died in 2011 of heart failure².