EYELASH GROWTH
The eyes have long been recognised as an important facet of physical beauty. For thousands of years, women have employed techniques to enhance the prominence of their eyelashes. Eyelashes are not just pretty; they can defend the eye against debris and trigger a blink reflex serving a protective function against airborne particles.
Ways to enhance the prominence of eyelashes
There are many options for enhancing the appearance of eyelashes. Mascara is a temporary solution but can smudge. Eyelash extensions or artificial eyelashes, which may use methacrylates-based adhesives and are removed by solvents, can cause allergic reactions. Eyelash transplantation, a permanent and invasive method, typically transfers hair follicles from the scalp onto the margins of the eyelid. This results in eyelashes that have qualities of scalp hair and require regular trimming and curling. Most recently, a topical bimatoprost ophthalmic solution has been approved by the American Food and Drug Administration (FDA) for the treatment of hypotrichosis of the eyelashes by increasing their growth and enhancing length, thickness or fullness, and darkness.
Eyelash Growth Cycle
The eyelashes on each upper lid are arranged in two to three rows for a total of about 100-150 lashes. The normal eyelash growth cycle, like all hairs, can be divided into three main stages: anagen, catagen, and telogen. At any one time, some hair follicles are growing (in anagen) while others are dormant (in telogen). The normal eyelash cycle is variable and lasts approximately 5-12 months. The growth phase of the eyelash follicle, anagen, is approximately 1-2 months long. Anagen time largely determines hair length
After completing anagen, hair follicles enter the transition phase, catagen when the epithelial elements of the follicle undergo programmed cell death. In eyelashes, this phase takes around 15 days. From catagen, the eyelash follicle enters telogen, the resting phase, which can last from 4-9 months. The “old” hair is expelled from the follicle during the transition from telogen to anagen.
Eyelash versus scalp hair
Although the basic hair cycle is similar between eyelashes and scalp hair, a number of distinct differences exist. Such differences alter growth patterns. At any given time, approximately 41% of upper eyelid eyelash follicles are active, compared with approximately 84% of scalp follicles. Scalp hair has a much longer anagen phase and a shorted telogen phase than eyelashes, scalp hair follicles can grow and remain in anagen for as long as 8 years.
The number and distribution of hair follicles are determined before birth and remain constant throughout life. Although there is no therapeutic approach for increasing follicle numbers, changes in the hair cycle, induced physiologically or pharmacologically, can affect the number and quality of hair visible to clinicians and patients.
There are currently tow FDA approved drugs for the regrowth of scalp hair: minoxidil and finasteride. Minoxidil is approved for over the counter use as hair growth treatment. It was originally approved as an antihypertensive agent and is believed to promote hair growth via its action as a potassium channel opener. Minoxidil requires continuous application to the scalp to sustain results. Finasteride is indicated for the treatment of androgenetic alopecia in men. It acts as an inhibitor of type II 5α –reductase, an enzyme that converts testosterone into 5α-dihydrotestererone (DHT). In genetically predisposed individual, androgens such as DHT can lead to the conversion of terminal scalp follicles to vellus follicles, a process that finasteride can prevent or reverse. Unlike their effects on scalp hairs, androgens have no effect on eyelash.
The differences between scalp hair and eyelashes have important implications for the development and use of hair growth drugs on these hairs. The characteristics of the eyelash growth cycle suggest that treatments that initiate or prolong anagen may have more immediate, visible effects on eyelashes than on the nonbalding scalp.
What’s new for Eyelash Growth?
Bimatoprost is an eye solution approved in 2001 for the reduction of high intraocular pressure (IOP), in patients with open-angle glaucoma or ocular hypertension. It is considered the most efficacious anti-glaucoma drug available, and its safety and effectiveness as an IOP-lowering agent has been established in clinical trials lasting up to 4 years. It was interesting to note that eyelash growth was recorded as an adverse event with use of this agent as an eye-drop. In a year-long controlled trial, 42.6% of patients treated with Bimatoprost once daily experienced eyelash growth. However, the changes in eyelash growth were not quantified, making it difficult to compare the effects of Bimatoprost with placebo or an active comparator. Eyelash changes have also been reported for other drugs used to treat glaucoma, including the prostaglandin analogs latanoprost and travoprost.
Bimatoprost – mechanism of action and its FDA approval
A paper funded b y Allergen, the company that makes Bimatoprost, revealed that treatment with Bimatoprost results in multiple changes to the hair cycle of eyelashes. A greater proportion of follicles in the anagen phase and a concomitant decrease in the percentage of follicles in telogen were observed. Such changes accounts for its ability to lengthen lashes. It has also been shown to stimulate melanogenesis resulting in darker lashes. There is also the possible side effect of darkening the iris, the colour of your eyes.
Now Bimatoprost ophthalmic solution 0.03% has recently been approved by the American Food and Drug Administration (FDA) to be used for the treatment of hypotrichosis of the eyelashes by increasing their growth and enhancing length, thickness or fullness, and darkness.
It is being marketed in the US as Latisse by Allergan, the company that makes Botox and Juvenderm fillers. The recommended US retail price for a 3ml bottle of Latisse solution and 60 disposable applicators (one for each eye) is US$120.00. However, it is unsure when and if it will be approved in Australia, for use as an eyelash treatment, although it has been approved in glaucoma treatment. Read more: http://www.smh.com.au/lifestyle/beauty/no-more-mascara-now-you-can-grow-your-own-luscious-lashes-20111010-1lh6x.html#ixzz2WWn7eBIW