You may have seen negative reports about sunglasses, with amateur claims suggesting they block vitamins or disrupt your sleep cycles.

That is fake news, say specialists who recommend you wear shades if you are heading into bright sunlight as they protect your eyes from the sun’s glare and from harmful ultraviolet (UV) rays.

Pick a pair with a UV filter of 400, doctors say, as they block UV rays in the 280 to 400 nanometre wavelength range, which can hurt your eyes.

You also want larger shades, as they offer benefits beyond looking cool.

The more your sunglasses cover your eye area – meaning the front and the sides – the better.

That does not necessarily mean they will be more expensive; you can find inexpensive pairs with the appropriate UV filter.

Generally, you want to wear some form of eye protection when the UV index is three or higher.

You can usually find that information online provided by local weather services.

The retina of your eye is the only part of your central nervous system that comes into direct contact with UV light, says Germany’s Eye Foundation, which is dedicated to research, training and education in ophthalmology.

This is particularly true for children and young people as the lens’ function as a UV filter is not yet fully developed, says Germany’s University of Bonn Ophthalmology Department medical director Prof Dr Frank Holz.

But even in adults, UV rays can impair eye health, says Germany’s University Hospital Dusseldorf Ophthalmology Department director and Eye Foundation media spokesperson Prof Dr Gerd Geerling.

You can get malignant skin cancer of the conjunctiva.

Different types of eyelid cancer are also known to be promoted by UV light.

Last but not least, high UV exposure accelerates the development of lens opacity (cataracts) because the high-energy light damages the proteins in the lens.

So, if you see social media warnings about sunglasses promoting cataracts, they are incorrect.

Sunlight hits at eye level in the morning and evening hours, so you want to wear your shades for longer than just at midday.

Take extra care at the seaside and in the mountains as the sunlight is even more intense there as it is reflected by the surroundings.

Some even say you should deliberately squint in bright sunlight for better health, but that is misleading.

Wearing sunglasses does not affect your body’s production of vitamin D as the area of skin around your eyes is much too small for this. And anyway, sunglasses do not prevent sunlight from reaching your eyes.

Depending on their tint, they merely absorb a large proportion of this light, says Heidelberg University Hospital ophthalmologist Dr Klaus Rohrschneider.

Even if you are wearing sunglasses, more light still reaches your eyes than on a cloudy winter day.

So likewise, pay no heed to anyone saying sunglasses disrupt your biorhythm. – By Ulrike von Leszczynski and Alina Schmidt/dpa