Firstly make him sit straight to watch tv with proper distance as when they see while sitting straight they dont tense there eye muscles. keep it as a practice it helps in there vision. My son started doing this as well. he was over 2 1/2 years old when it started. It would get worse if he was sitting idle or watching T.V. and even more so if we called attention to it. Our pedi, said it was most likeley a transient tic that would go away by itself. she said to completley ignore it. he also reassured me that there was nothing my husband or I did to cause it. I was afraid it came on by stress since we were batteling bedtime issues at the time. Within a week they completley disappered. I did some reading on it in my nursing textbooks and It is very common to develop a transient tic during that age. The theory being that so many developmental milestones are being reached and peaking at that age, and the brain is rapidly fireing signals causing this. So definetly ignore them, although if they persist, you probably should follow up with a nuerologist who specializes in tics.
Squinting and blinking may be a sign of tired eyes. Limit your child’s tv time to an hour every day. Any longer than that, could strain his eyes. Besides watching tv , you can encourage your child to play, draw or read a book. You could also bring them to the playground. Another important thing is the distance between your son and the TV. It should be more than 2 meters. Also, watching tv in a well-lit room is also better for the eyes. Always let your child have ‘eye breaks’ if they are watching TV or reading or studying. A rough guide is to have a 10 minutes ‘eye break’ every hour.