Unfortunately, I have to say that it may be because of the eyelash extension you have used, causing eye irritation. Generally speaking, by using eyelash extension for a long time, it can lead to some serious eye diseases, such as the eye infection. And then it can make your eyes feel irritated, and red, even bloodshot. As we know that eyelashes extensions are placed directly to the natural eyelash with a bonding agent. In this way, they can carry some bacteria and also be the irritants. Finally, it can lead to eye irritation, causing red eyes. Maybe pink eyes and dry eyes will occur too. So if you do have this symptom, just give up using the eyelash extension. And some eye drops will be helpful.