They do grow but the rate of growth is so slow that the patient may become concerned. Eyebrow follicles are also sensitive to injury. Plucking an eyebrow follicle once or twice may lead to extensive and irreversible destruction and no further hair growth. Eyelash hair is very similar to eyebrow hair. Average length is around 7.5mm and the growth rate is about the same as for eyebrows.
Eyelashes are very important in protecting the eye from dust and debris.
People without eyelashes have frequent problems with eye contamination and a possible increase in eye infection that requires regular attention from an ophthalmologist. Scalp hair is terminal hair unless the hair follicles have been affected by disease such as androgenetic alopecia. Terminal scalp hair grows in a clockwise whorl pattern on the top of the head with merging of this pattern into hair angled downwards and away from the face around the ears and lower back of the scalp. These hair follicles produce thick, coarse, terminal hair. The hair follicles are some of the fastest producers of hair with a mean growth rate around 0.38mm per day.