Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
The question related to what makes the eyesight better should be directed to ophthalmologists, who are able to answer it properly.
However, we would like to advise you to avoid letting your children stay long periods of time watching TV or using computers in profitable good, and lawful programs. let alone letting them watch or see things that could harm them spiritually or physically or that could affect their creed even if watching such things is not harmful to their eyes.
On the other hand, there is no doubt that the Qur'an is a cure for both the body and the soul. Looking at it is a form of worship as reported in some narrations. The majority of Fuqaha (Muslim Jurists) are pleased when a person looks at the Qur'an as much as possible.
Allah knows best.