Can someone who is "half-blind" only see with glasses on?

Half Blind is an expression. It isn't a definitive measurement of anything.....just an expression.

Anyone who has trouble to see whatever , can say they are half blind...it doesn't mean they are any where near blindness.

You can be looking for the TV remote all over the house until someone points out it is right on the kitchen table.....you may say , I must be half blind, I never saw it there at all....even though you have perfect vision.

Like saying you are half deaf because you didn't hear someone say something to you...it doesn't mean you are REALLY half deaf.

Half-blind people are those having a limited capacity to see. They definitely need a spectacles for a clear vision if not the vision will be blurred.

It depends on what the definition of blindness is. Some places call any vision beyond 20/400 legally blind.