In children and young adults whose eyes are still growing, increased use of the eyes at near (computer, reading) as opposed to use of the eyes at distance (outdoors) appears to be related to increased near-sightedness. However its not clear if mid-distance use of the eyes has such an effect. The website AAO.ORG is a good resource for additional information.

Watching TV across a room is not bad for myopia. Reading and computer are more contributory to myopia. Take breaks every 20 minutes for 20 seconds by looking into distance at least 20 feet away.

There is no definitive answer to this but if you can take breaks every 20-30 minutes from watching, that may help the myopia from getting worse. Frank Cao

Nothing is bad! Just do it in moderation.