Much like almost any hair on your body, eyelashes have a lifecycle. But this lifecycle encompasses three separate phases. They grow, change and then rest before they fall out. When eyelashes are burnt, the growth process has simply been disrupted.
As long as the burning hasn't affected the follicle, your eyelashes will grow back. This is largely because of the perpetual growth cycle of your eyelashes. On any given day, you have lashes that are going through a growth phase, a transition phase or a dormant phase. The only ways in which you'll maintain any hair loss is if the follicle itself is damaged, according to the Mayo Clinic, or scarring along the lid prevents the growth of new hairs.
If you've completely singed the lashes from your eye, it might be awhile before you notice hair growth. It can take anywhere from 30 to 45 days for a lash follicle to complete its growth phase, also known as the anagen phase. From there, the lash will evolve during the next 14 to 21 days through the catagen phase, where the follicle shrinks and the hair no longer grows. The remaining time that the lash remains on the lid, the follicle is dormant until the lash falls out and the cycle begins again.
If you were to burn off your eyelashes, make sure to check the skin of your eyelid for signs of burn. Redness, swelling and pain are usually signs of a first-degree burn. With a second-degree burn, you'll usually notice the same type of redness that is not only accompanied swelling and pain, but also blistering. Third-degree burns are the most serious and usually appear blackened or even white and are usually not accompanied by any sort of pain.
Your eyelashes protect your eyes. Without lashes, your eyes are far more susceptible to debris and UV rays, which could cause damage and dryness that could affect your vision.
Most of the time, burnt eyelashes aren't a cause for alarm. However, if they're accompanied by any sort of pain or blistering of the skin, seek medical attention.