Introduction
There are few parts of the human body that impart character, emotion and communication as evocatively as the eyebrows. These small but well placed hair bearing structures have been shown in studies to have similar importance to the eyes in facial emotional recognition and furthermore have complete sexual dimorphism; they are a critical aesthetic feature of the face.
What is the purpose of the eyebrow?
The eyebrow protects the eyes from sweat, sunlight and other substances that can fall from above into the eye. Furthermore, it frames the eyes and directs attention to them. They have a role in non-verbal communication; the expression of sympathy, anger, emotions, concentration, cognitive state and so on.
What is the eyebrow like?
A typical eyebrow is about 5.5cm long and 1.3cm wide. The average distance between them is 2.3cm. In women, the eyebrow rounds and ‘lifts’ with the angle of inflection maximal at the ⅔ mark from inner to outer; this is where the iris or coloured part of the eye begins. The eyebrow then tails downward to the lateral orbit (the bony rim of the eye)
In men, the eyebrow has a flatter angle; it does not elevate as high at the ⅔ mark and flattes downwards; moreso if a man is looking dark and mysterious or giving a good smolder.
Where is an eyebrow?
The eyebrow sits over the superciliary ridge of the frontal bone; the top of the bony eye socket. There are a number of muscles that are attached to this bone that move facial expression and they take the eyebrow with it. Thus the eyebrow is capable of imparting much expression. It is also subject to facial aging and thus the popular cosmetic procedure of a ‘brow lift’ is commonly employed.
How does eyebrow hair grow?
In contrast to the hair on our scalp, the hair on our eyebrows behaves a lot more like the hair on our eyelashes. It has a shorter growth phase, a matter of 2-4 weeks, followed by a quick regression phase (catagen) and a long period of telogen where there is no growth and an eventual falling out. This lasts a few months.
Managing eyebrow loss
There are special words for loss of the eyebrows; madarosis means to fall out and hypotrichosis means less hair. Somebody who is born without eyebrows should see a skin doctor. If there is loss of eyebrow hair, an evaluation by a doctor for underlying causes is strongly recommended; including a look at certain infections such as syphilis, hormonal problems such as thyroid, autoimmune check up and a general set of investigations.
A particular condition, called frontal fibrosing alopecia, involves loss of the lateral third of the eyebrows and often the temporal hair (hair in the angles of the upper forehead) being lost; it occurs more commonly in women and can be permanent. These patients often required hair transplantation.
Treatment of eyebrow loss.
At present there is no standard treatment for a lack of hair on the eyebrows. The general treatment would consist of treating any underlying causes and then increasing the growth of the hairs on the eyebrow.
There are a few treatments that have been used and recorded in studies. Minoxidil, used in the topical hair loss treatment called Rogaine, has been used in studies on the eyebrows with satisfactory effect. Because it takes some time to work, it needs to be applied once or twice daily for a few months before the effects can be seen.
As discussed in an article on eyelashes, bimatoprost is a medication that was incidentally found to increase the growth of eyelashes. When applied to the eyebrows, there are reports of increased eyelash growth to the satisfaction of patients.
How to take these treatments?
For anybody with a loss of eyebrow hair, this can be a distressing facial alteration. Medical therapy is a suitable first line due to lower cost and minimal disruption compared with surgery. The use of once daily topical solutions such as minoxidil and bimatoprost is generally safe and recommended as a first line.
Care should be taken to only apply to the areas of intended hair loss; a stencil like frame can be used to achieve this. Some patients may have skin irritation and any side effects of this nature can be discussed with your doctor. The rate of a return to hair growth is variable but results should not be expected before 3 months.
What further treatments are there?
After a trial of medical therapy, surgical hair transplant is the definitive option. Hair transplants are a well established technique whereby hair follicles are moved from the scalp to another area. By moving hair follicles to the eyebrows, it has been demonstrated that the hair follicle will survive and prosper in the new location. In the early days, the hair will grow longer and require regular trimming; in some cases, the hair will ‘adapt’ and grow like eyebrow hair.
Eyebrow transplant remains the gold standard for eyebrow restoration. A discussion on this technique is beyond the scope of this article and will be covered elsewhere.
REFERENCES
Chanasumon N, Sriphojanart T, Suchonwanit P. Therapeutic potential of bimatoprost for the treatment of eyebrow hypotrichosis. Drug Des Devel Ther. 2018;12:365-372. Published 2018 Feb 22. doi:10.2147/DDDT.S156467
Lee S, Tanglertsampan C, Tanchotikul M, Worapunpong N. Minoxidil 2% lotion for eyebrow enhancement: a randomized, double-blind, placebo-controlled, spilt-face comparative study. J Dermatol. 2014;41(2):149-152. doi:10.1111/1346-8138.12275
Sadr J, Jarudi I, Sinha P. The role of eyebrows in face recognition. Perception. 2003;32(3):285-93. doi: 10.1068/p5027. PMID: 12729380.
