Retinal tears, detachments, and glaucoma are the biggest risk factors in your 20s and 30s so sports (like weightlifting) that intensify pressure in your head if not done correctly should be approached carefully. Other sports that could cause blows to the head (football, soccer, boxing) should be avoided. That being said, don't live your life in fear of a tear or detachment. If you enjoy a certain sport, do it! But just approach it with an extra measure of caution.