For your prescription, it is not that necessary for you to wear glasses while watching TV, but if you really have problems while watching TV, you can buy yourself one which is only used for TV. It is possible that your vision will get worse if you wear glasses all the time.
It just depends on yourself. If you can see the TV screen clean without glasses, there is no need for you to wear glasses.While if you can't see clearly while watching TV, you'd better go to your optician to get a pair of prescription glasses.The doctor will give you an eye exam to test your vision.
I think there is no need for you to wear glasses.As your prescription is low,reducing the time of wearing glasses will be good for your vision.But if your eyes feel tired when watching TV,you may need wearing glasses.