Vision-damaging injuries are rare but frightening. Here's how to gauge the severity of an accident—and how to treat it.

ABRASION (Refer Fig. 1)
Problem: You're trail running and you don't see a branch until it whacks you in the eye. Most likely, your cornea has been scratched.
Treatment: "This is one of the most common sports eye injuries we see," says ophthalmologist Elizabeth F. Baze, director of residency training at Baylor College of Medicine's Cullen Eye Institute. Most of the time, abrasions cause watery eyes, light sensitivity, and a scratchy sensation. If symptoms are minor and your vision isn't blurred, patch the eye with gauze and allow it to heal for 24 to 48 hours. If your vision is affected or the abrasion is extremely painful, patch it and see a doctor.

LOST CONTACT (Refer Fig. 2)
Problem: A Class V rapid sends you and your kayak through the rinse cycle. When you emerge, you're short one contact lens.
Treatment: Take stock: How well do you see without your contacts? If the answer is "fairly well," go ahead and take the other one out. Your depth perception and balance will be better even if your vision is slightly blurred. If you're blind without contacts, leave the remaining one in place. One good eye is better than none.

BUNGEE-CORD INJURY
Problem: While lashing a canoe to the roof rack, you lose your grip on the bungee cord, which pops you in the eye.
Treatment: Hopefully you saw this coming and closed your eye before the cord smacked you. Even so, your eye could be seriously damaged. Treat minor irritation like an abrasion, but for severe pain head to the ER.

FOREIGN OBJECT (Refer Fig. 3)
Problem: You're cruising singletrack when a bug, dirt, or a leaf flies into your eye.
Treatment: Don't rub. Instead, flush the eye with saline or artificial tears to remove the irritating substance. If you can't wash it out or if the eye becomes red and inflamed, see a doctor. "If you get vegetable matter in the eye, there's a higher likelihood of infection," says Baze.

SNOWBLINDNESS
Problem: You're at 13,000 feet on the way up Rainier when you lose your shades. You soldier on to the summit, but the next day your eyes feel like sandpaper and you can barely see. Powerful UV rays at altitude and intense glare caused by snow have sunburned your corneas.
Treatment: Most cases of snowblindness heal quickly and don't cause permanent damage (though multiple eye burns can lead to long-term problems such as cataracts). Remove contact lenses (if you wear them) and avoid rubbing your eyes. Place a cold washcloth or compress over your closed eyes to soothe the pain. Cover your eyes with gauze pads and take it easy for the next day or two. If the pain doesn't begin to subside after 12 hours or if your eyes are swollen shut, see a doctor. Next time you lose your shades, fashion makeshift protection by cutting horizontal slits in a bandanna or in overlapping pieces of duct tape.

BLUNT TRAUMA (Refer Fig. 4)
Problem: A line drive bounces up and clocks you square in the eye.
Treatment: The blow may have fractured your orbital bone or damaged the eyeball itself. Sometimes blunt trauma can cause hyphema, or bleeding in the front of the eye. If there's an emergency-care ophthalmologist nearby, make a visit. If not, hit the ER. All hyphemas need monitoring, but most heal without permanent damage.