Yes, it can. There are some real cases where under eye fillers have led to blindness. The fillers can accidentally be injected into a blood vessel, which then can block the blood flow to the eye. This lack of blood supply can quickly damage the optic nerve and result in blindness. It's a very serious risk associated with this type of cosmetic procedure.
Yes, in rare cases, under-eye fillers can cause blindness. This is usually due to complications during the injection process that affect the blood supply to the eye.
Yes, they can. Besides blindness, there can be allergic reactions. Some people are allergic to the filler substances, which can cause swelling, redness, and pain. Also, there can be uneven distribution of the filler, leading to an unnatural look. True stories tell of people having to deal with these issues for weeks or even months.
Yes, manga can have fillers. Sometimes authors use them to flesh out characters or settings, or to give themselves more time to plan the main plot. But too many fillers can make the story drag.
The Naruto manga itself doesn't have fillers. Fillers are a common thing in anime to extend the runtime or bridge gaps in the manga's story. But the manga sticks strictly to the main plot.