Of course it is true that sunshine is extremely strong and sensitive to most of us. And as a matter of fact, sunglasses are designed to protect our eyes, not helping us to looking directly at the sun, in that way, our eyes would still be hurt and get some serious consequences. Thus, I suggest you stop doing that ever and never. Also try to protect your eyes and pay attention to your use of eyes.
Yes, the intensive sunshine will hurt your eyes. You need to wear the sunglasses to help you from the sun. It is safe for you to look at sun through the sunglasses because the special material of the lenses will protect your eyes from the uv rays and other bad lights. Or else, your eyes will become red after the burning which will make you feel itchy.
It really depends on the quality of your sunglasses. When you try to protect your eyes from watching the strong sunshine directly, You need an eclipse viewer, a pair of welders' glass, black polymer filter, specialized astronomical equipment, metal coated glass or mylar filter certified for visual use. They can filter the UV radiation. By the way, optical viewfinder is forbidden. But due to the relatively poor law system to enforce the quality of the sunglasses on the market, you may get a pair of sunglasses with inability to protect your eyes even it costs you a lot of money. As we all know, our eyes protect themselves from exposing to the light more by shrinking the size of the pupils. Your tinted glasses appear to reduce the intensity of the sun to a comfortable level, so that your eyes keep dilated. Once you open again, it will hurt. Further, it would be better if you werenâ€™t wearing them at all when you get a fake anti-UV sunglasses because it can't filter the invisible infra-red or ultra-violet radiation with dangerous amount, which will lead to retinal burns.