Apples contains many vitamins such as vitamin C and vitamin A which are good for the eyes because these vitamins can help prevent the eyes getting faitgue and dry, as well as removing the oxygen radicals produced by metabolism in the eyes so as to prevent the eyes from getting cataracts. Also, apples can be used in external application except eating them. You can cut an apple into several thin pieces and then put one piece of the sliced apple on each one of your closed eyes for about 15 minutes. It will effectively remove your black eyes and swelling eyes.
Apple is delicious and useful as it reduces the risk of colon cancer, lung cancer and prostate cancer and decreases fatty liver, obesity and glucose intolerance diseases. As for its eye protection function, I assume that apples are great for our eyes due to its high contents of Vitamin A according to recent studies. Scientists have found that lower levels of circulating vitamin A in our body are associated with eye dryness and damages to our nails, hair and skin. As our body needs some trace elements to regulate and control our circulation, we must take in enough fruits and vegetables. As the common saying: " an apple a day, keep doctor away". By the way, I like eating apples very much.