In vision area I can see small black dots, tiny black lines. Hard to notice in daily life but visible if to look into white background.?

Floaters. These are vitreous floaters. They form as the vitreous jelly breaks down as you age. The sudden onset of floaters and flashes may lead to retinal tears and possible retinal detachment . See an ophthalmologist as soon as possible.
Floaters. You seem to be describing floaters - a condition in which the gel that fills the back of the eye liquifies and breaks into smaller pieces. You can see the small pieces floating in the gel in bright lighting or when looking at light backgrounds. Although they are annoying, they are usually not dangerous; they also cannot be fixed. If they are new, large or there is vision loss, see an eye doctor.