Always a good idea. There is a risk in sports of eye injury. Especially ones with the ball, etc. Small enough to directly impact the eye. Main offenders are squash balls, badmitten birdies and paint balls. If it is possible, eye protection should always be worn in such sports and it is highly recommended.
Impact resistant. Sports glasses that are impact resistant/ shatter proof (polycarbonate) are sufficient. I also recommend an attachment to the bows (a croakie) to anchor them so as to prevent them from getting knocked off. You can also find frames that wrap around the ears to keep the glasses in place. Also sports vary on the type of recommended eye & head protection aides.
If you wear glasses. Everyone participating in a sport that has a high risk for injury to the eye (such as racquetball) should wear some type of eye protection. You may consider wearing customized glasses if you normally wear corrective eyeglasses so that your protective eyewear also corrects your vision.