Impact from a ball or other device may cause blindness.
I had a patient come in today suffering from eye pain subsequent to being hit by a volley ball approximately 12 hours ago.
Fortunately there was no current damage to the eye. However such impact even small today may cause issues anytime later in life. Never assume the eye is healthy. Advice given to the individual, is to be observant for the appearance of flashes of light, alot of black dots or strings in their vision.
If it does appear, call immediately for an evaluation.
Otherwise, it is recommended to have yearly assessments. You may be oblivious to any conditions presenting themselves in the eyes or the visual system.