I know screen time is bad in general for kids. But what is maximum time they should spend on screen time daily?

With regard to whether looking at the screen will cause damage to your child’s eyes, this article suggests that the blue light emitted from devices may be harmful to children. Adults are less susceptible as the lens in adults’ eyes gets yellow with time and could block out some of the blue light. In young children, however, their eyes are still developing and blue light is able to penetrate much more efficiently and directly into the retina and may cause damage to the back of the eye. If you allow your child to handle electronic devices, remember to factor in break times and remind your child to use the device at appropriate distance (i.e. not holding it too close to their faces), also remind your child to blink (to minimize dry eyes). Experts recommend taking a break every 20mins and looking to objects in a distance to help reduce strain on the eyes. For more information: http://www.dailytelegraph.com.au/entertainment/arts/your-childs-phone-and-tablet-could-be-harming-their-eyes-expert-warns/news-story/c91174a8dcd55d0e70f0836144a403c5