Hey Candice,
Vaseline won't do any harm to you lashes or make them fall out. The way that it works in aiding your lashes is that it helps to condition, protect and strengthen your lashes. The reason people say that it gives them longer, fuller lashes is that it pretty much just makes them healthier and stronger, allowing them to grow better and not fall out easily. It won't hurt to try it, and it won't damage your eyes. It's also a cheap alternative. The only downside of it is that it might be tedious to do everyday. I suggest you give it a try. There is nothing to fear, and in the end, it IS healthier for your lashes as your lashes tend to dry out due to mascara and the winter months, ending in them falling out faster and easier. Shedding lashes however is just like shedding hair. Lashes naturally will rejuvenate and replace themselves every month or so.
Apply some vaseline to clean lashes at night before you go to bed, and in the morning make sure to gently wash if off using an oil-free makeup remover.
Good luck!