Perhaps it is due to the bright light. After staying in a dim place for a long time, our eyes have to adjust to the light when walking outside. At this time, our pupil gets smaller, making our eyes feel uncomfortable and painful. Or your eyes hurt because you have overused your eyes, under such circumstances, you need to massage your eyes to relieve the discomfort or you can apply cool compresses to your eyes to soothe the pain. In your daily life, take a diet rich in vitamin A, beta carotene, antioxidant, fish oil and zinc rich foods such as livers, milk, eggs and vegetal foods like carrots, amaranth, spinaches, leek, green pepper, sweet potatoes, cucumber, cabbages, dates, salmon, krill, cod and tuna. Do some eye exercises and ensure enough rest of eyes. Wish you better soon.
You should check whether the environment surrounds you is clear at the air or other sides. If there is a lot of dust or other dirty things around you, your eyes may easily get some and get eye infection. You'd better clear your eyes with clean water after your walk. You could use some eye drops with anti-inflammation to clear the eyes.
Many reasons can cause this condition. Corneal abrasion and dry eye are the most common reasons. Foreign object goes into eyes is the common reason, such as finger scrach, contact lenses. Accept for pain, symptoms like sensitivity to light, tearing, blurry vision may also have. Dry eyes can also cause eye pain, light sensitivity. As we know, sunlight contains many harmful lights to our body. So it is easy that sunlight burn our eyes. So when you go outside, you had better wear sunglasses to prevent UV rays and other harmful rays. Certainly, some eye diseases can also lead to eyes hurt, such as conjunctivitis, uveitis, scleritis etc. So if your condition become serious and frequent, you should go to see the doctor.