With normal and proper application, eyelash extensions should not affect natural lashes in any way. The appropriate application of the extension is done on natural eyelashes (usually an extension on a natural eyelash, but if the eyelashes are thicker, they may be able to withstand two or three extensions on one eyelash). When they affect the lash line, they can damage hair follicles and result in loss of eyelashes, not to mention swelling, pain, itching, and redness. Not only will they not look their best, but when the extensions fall off, they'll take the natural lashes away and leave them with uneven lashes.
Mascara applicators should be avoided, as they would cover the entire eyelash and cause the volume extensions to clump together. Depending on the thickness of the individual extensions, this can be quite stressful for your natural lashes. In fact, I was very proud of the natural lashes, they were very full, I only did the extensions, for a special occasion. Eyelashes can fall out for many reasons, apart from extensions, such as rubbing them hard to remove the waterproof mascara, using a product that irritates the eye area, or even due to stress.
After using Nova Lash extensions for almost a year, I have noticed that my eyelids itch for about a week after filling. My lashes were very long, but almost straight and not dark, so the only reason I put on eyelash extensions was because I was tired of curling them every morning and putting on mascara. So it's no wonder that, like thousands of other girls, I've always wanted to have longer, thicker eyelashes. The next major cause of eyelash damage is not taking good care of your eyelash extensions after you've done them.
If you have blue, green or other light-colored eyes and you don't trust the entire staining effect of the iris, you can get fantastic eyelash conditioners that don't fall into the category of prostaglandin analogues, so you can avoid any side effects. That said, no one is saying you can't “cheat” and help speed up the eyelash growth process a bit.