Dr. Aaron Fay, an ophthalmic plastic surgeon at Massachusetts Eye and Ear Infirmary in Boston, revealed to NBC News that the extra row of eyelashes grows in place of oil glands. "What happens in distichiasis is that a hair grows where there is supposed to be an oil gland on what's considered the wet part of the eyelid," he explained. As a result, some people with the disorder experience reduced vision and tearing of the eye. Healthline also lists sensitivity to light, conjunctivitis, and droopy eyelids as other possible side effects. While this is often treated with eyedrops, Fay says the best way for people with distichiasis to protect their eyes is simply to wear contacts. If symptoms persist, it's best to seek the help of your doctor.