Wear the damn sunglasses! Apparently, yes, too much sun exposure can damage your eyes. Heavily! Even though only a few rays of sunshine shine out from behind a cloudy sky, I immediately wear sunglasses. Often I walk around and am the only person in the world with dark sunglasses on my nose, while all the other people can stand the sun pretty well. But as soon as it’s almost bright and glaring, my eyes start to weep, and my eyelids would like to close immediately, so I rather wear darkened glasses. But, as it turns out, I did everything right – a sunburn on eyes can actually happen, and you should not provoke something like that carelessly!
Even if you do not suffer from sensitive eyes, as I do, you should wear sunscreen for every “strong” sunshine. Just as your sunscreen for the skin anyway used every day. Because, even in cloudy weather, the UV rays can damage the eyes, and increase the (long-term) risk of cataracts and macular degeneration. One short-term effect of UV exposure of the eye is acute photo-keratopathy, which is essentially a sunburn of the eye. Sunglasses also protect the eyelids, hence the importance.
Incidentally, UV radiation can also cause pterygium, which spreads to the white area of the eyeballs. If they get worse, they may develop a pinguecula (“surfers eye”), something you really should not look for in Google Image Search … unless you need a new reason to wear sunglasses to protect your eyes.
When wearing sunglasses, it is primarily about the sun protection of the eyes; important for this is the blocking of UV radiation. So do not buy sunglasses in the 1 € shop, but rather look for glasses that block 99-100 per cent of UVA and UVB rays or UV absorption of up to 400 nm in a professional local business. By the way, the degree of tinting of the glass (i.e. light lenses or darker glasses) has absolutely nothing to do with the protection against UV rays!