I’m a student. so every day I have to write to do the assignment given. if I write using differential while writing then I don’t get blur. So do I have to remove my differential when writing because I don’t get blur?
Do you mean typing text or handwriting? You don’t ‘have to’ do anything, but if you can write easily without wearing any glasses, it might be nice to give your eyes a break from them. If this means taking off and putting on your diffs too often, perhaps you shouldn’t bother. You don’t need to be at the edge of blur all the time.
It really depends on how much blur you get without correction and how long you are writing for. Habituated blur is not the point, but you risk spasm being overcorrected for near work. And that is to say nothing for the fact that depending on your level of myopia and the correction you are wearing while writing; you may well be giving your eyes the stimulus that progresses myopia and this will naturally work against your efforts to reduce it.
If you do a lot of this work, there’s always the option of having a weaker pair of differentials for the closer focal plane.