You should know looking up at the TV with your head tilted up will cause more eyestrain than if you’re looking straight on at it.

Having the TV below your eye level, so your head is tilted down, also produces less eyestrain than if you’re looking up at it.  The same type of thing applies for computer monitors, so it’s generally better to keep your monitor straight on or below your eye-level.

That being said, eyestrain is nothing serious and at worst might give you a headache.

What also is not anything to worry about is sitting really close to a TV or monitor.  The old adage that sitting too close to your TV will damage your vision simply isn’t true.  Once again, at worst, it will simply result in eyestrain.  Go here to find out how that particular old wives’ tale got its start: Sitting Close to the TV Will Not Damage Your Vision