Yes, they should look good otherwise they would not be worn. But most of all sunglasses should protect the eyes from intensive UV radiation. Although in medium latitudes it is not necessary to wear sunglasses outdoors. But when the light reaches very high intensity, especially during midday, in the mountains and near water or snow, sunglasses should be worn to protect the eyes.
Intensive sunlight can damage the eyes
As the skin suffers from too much sunlight so do the eyes. Some of the intensive light gets absorbed by the cornea, the eye lens, and the vitreous body. Most of the UV radiation however goes through the eye to the retina and hits the macula directly. This is especially dangerous for blue-eyed and light-skinned people.
UV damage adds up over life
Many people are not aware that intensive UV-light is one of the causes for the development of cataracts, fogging of the vitreous body, and age-related macula degeneration (AMD). Therefore, UV-protection starts in childhood.
Therapy for AMD is limited
Age-related macula degeneration is one of the most frequent causes of blindness in western countries. About 30 percent of 75-year-olds suffer from AMD. There are two forms: dry and wet. Dry AMD is the most frequent, develops slowly and there is no therapy. The wet form is less frequent and more aggressive, and there is limited treatment available.
Cataracts and floaters in the vitreous body
The cloudy lens and floaters in the vitreous cause glare, high light sensitivity and reduce vision. A foggy lens can be replaced by an artificial lens but blurs in the vitreous body cannot be treated.
High short-term UV exposure
Extended exposure to high frequency UV light leads to corneal and conjunctival inflammations. Over exposure of cornea and conjunctiva causes permanent damage such as blurs in the cornea with vision decline and degeneration of the conjunctiva which causes dry eye symptoms.
Contact Lens wearers beware and have your cornea regularly checked!
The body's own UV protection
The body has protective mechanisms against UV damage. Lutein is an important body substance which provides UV-protection in the eye, especially for the macula. Like vitamins, Lutein cannot be produced by the body but comes directly from food. Besides Lutein, vitamin A, C, E, and the flavonoids have a protective effect on the eye.
Foods which contain Lutein:
UV Protection Scale for Sunglasses
00-20% Light UV protection usable also inside and at night
20-56% Medium UV protection for cloudy days and light sun
57-81% High UV protection on sunny days in mid latitudes
82-91% Higher UV protection on the water, mountains, and south latitudes
92-97% Very high UV protection for high mountains and glacier regions but not for driving
Good sun protection are hats with brims.
Bad for the eyes is squinting. It strains the iris and eye muscles and leads to vision problems.
Have fun outdoors and stay safe