A couple months ago I started noticing some weird floating things in the corner of my left eye. I became somewhat concerned, especially because once I noticed them, it became really difficult to stop noticing them all the time. I even started to obsessively check my corner vision every few minutes to see if they were still there and whether they changed position/size. As you can imagine, believing there may be something wrong with your eyes is not a particularly fun experience.
Luckily, today Laughing Squid pointed me towards this excellent TED-Ed animation, in which the nature of such phenomena is explained. It turns out, these things are commonly known as “floaters”, and they’re usually safe. They’re caused by tiny particles floating in the liquid vitreous humor inside the eye and casting shadows on the retina.
So, while in some extreme cases floaters may be the result of a more serious condition, their presence in small quantities is a very common occurrence and is usually no cause for concern. That said, if you’re experiencing similar symptoms and are still unsure as to what it could be, the best course of action is always to check with your doctor.
Update (01/07/2017): Check out this comprehensive guide to floaters at Laser Eye Surgery Hub for more information.