Myopic (myopia)…..what the risk when ignore to use glass??

Myopic (myopia)…..what the risk when ignore to use glass??
My friend is myopic (myopia) and he dont want use a glass or even a lens for his eyes. Whenever he want see something (like reading, watch TV) he force his eyes to see it and now his eyes become worse……… I want to know the risk of it and can his eyes be blind or blur if he still dont want use the glass or lens and keep force his eyes to looking at something….