Actually, when we are the six-month old baby, our vision developed as 20/20. That is to say, when we are 6 month old, we have got the normal vision and our vision has been stable. However, strictly, from then on, if you do not use your eyes correctly or you overuse your eyes, which will cause eye fatigue or eyestrain. Further, it will affect your vision, you will get nearsightedness or farsightedness. Strictly speaking, our vision will not get stable only if you use your eyes correctly and well protect your eyes. Hope this helpful.