Frequently in people with severe diabetic changes in the eye, the vitreous can become very cloudy due to hemorrhaging. Sometimes a remove of the hemorrhage is required to restore useful vision. Minimal amounts of hemorrhage can sometimes settle to the bottom of the eye and clear without surgical intervention. There are, however, some eyes that only transiently lose the ability to see light. It is very important to have a trained eye practitioner examine patients to make this determination.
Some people consider war the ultimate sport.
Wartime injuries to the eye have increased with each war. Fortunately, military has eye protection programs underway. If you exclude war, probably the most dangerous sport currently being played is paintball. The gelatin coated pellets shot from air guns during war games travel at 300 feet per second and can easily rupture the eye when fired from distances of 12 feet or less. I think the most important take home message is the greater than 90 percent of sports related eye injuries can be prevented with appropriate eye protection.