It is not a good habit to expose yourself in sun with naked eyes. The sunlight can burning your eyes, make you feel eye pain and tearing. So, if you want to protect your eyes well, you shall prepare at least a pair of sunglasses especially in summer time. With it, they can protect your eyes from UV rays. Besides, the sunglasses can also help reduce the strong light that can cause tearing.
I think you should better go to see the doctor and have a full check on the eyes. Your eyes may get the high possibility of infection from the bacterium. That is why your eyes starts watering when seeing the sun light. You should better have a good rest for the eyes before going to see the doctor.
Our eyes are very sensitive to stimulation from outside. When the sunlight shines your eyes directly, your pupil will be wider all by a sudden. The wider of our pupil will make our eyes blind in a short-term and change our crystalline lens. After that, you start to shed tears. So you don't have to worry about this. Eyes water is just a method to protect your eyes from hurting. However, in order to avoid this happens, what you should do is to donâ€™t look at the sunshine directly and wear sunglasses to exclude light.
Well, in my opinion, it is very normal to have this situation. As we know that the light is so strong that when we open our eyes to see it, it will just make the eyes be hurt. And also Our eyes are so very sensitive that they will react to the stimulation from sun light. When the sunlight get into our eyes, it will make our eyes to adjust to it. And at this time, it will water. So it is very normal. And there is nothing for you to worry about. But on the other hand, you should not make your eyes to be exposed under the sunlight for a long time, for it will lead to some eye diseases. Anyway, just be careful.