People think of sun protection as skin protection, seldom have eye protection in mind. Instead, surveys show that ultraviolet radiation is the main cause of some eye diseases, such as keratitis, cataracts, retinal damage. For that reason, we ought to care our eyes especially in hot summer. Don't look directly into the sun. Eyes are extremely weak. One may feel dizzy after looking up to sun for a short while. One may suffer from pain, tears, inflammation and blurred vision if he/she looks up to sun for a long time. As is well known, eye is a delicate tissue that is sensitive to UV rays. It can absorb UV rays with various wavelengths. The UV ray of 280nm wavelength damages the cornea most badly and it brings about the conjunctivitis. The UV ray of 290-400nm wavelength damages the lens badly, which is also the pathogenic factor of cataract.Some studies have shown that if people expose to the sunlight for one more hour every day, the risk of cataracts will rises by 10%.Then what should we do in preventing the harm? When you are outgoing in summer, remember to wear broad-brimmed hat or use umbrella, a pair bifical glasses is most effective in protecting your eyes. What is noteworthy is that the quality of progressive glasses is very important to the health of eyes. Inferior sunglasses will hurt your eyes rather than protecting eyes. They may cause mydriasis. Prepare a pair of UV-cut sunglasses for summer use, and you will benefit a lot. Medical studies have certified that lenses in grey are best as grey have little influence on the effect of vision but effective in anti-UV. If you wear contact lenses, you can choose those with anti-UV function which can block 90% ultraviolet rays.It would be safer to add a pair of progressive eyeglasses. The sun is strongest at noon, which is harmful to both your skin and eyes. You'd better stay at home without going out.