Mainly a direct blow to the eye like an elbow or fist. You may be able to order "sports glasses" from the optical place you buy glasses. There are polycarbenate impract resistent lens with strong frames that are double hindged to prevent the hinge screws of regular glasses from stabbing the eye. OR if he wears contacts you should be able to order from a European country or over the internet basketball sports googles that he would wear over the contacts. Some of the Olympic and NBA players wear them and many players deem them attractive to wear to protect eyes and the delicate bones that hold the eye up (prevent a "blow out" fracture).
JCHMD
Thank you for the answer.
We live in Lithuania and here the range of the eye protection is very mean.
In general, what should we avoid? Contact? Pressure?
Can't answer and your ophthalmologist is only one that can quantitate the risks. I do have myopes that pay BB and football but they wear eye protection/sports goggles.
JCH MD