【托福培训-阅读】托福阅读材料：眼睛变色的原因

托福阅读的关键是在于多看多练，为了帮助广大考生更好的复习，小编为大家整理提供托福阅读材料:达芬奇的成功源于阅读障碍.以供各位考生复习参考，生活中有很多事情需要大家细心观察和发现，阅读文章不仅可以锻炼能力还能了解各方面的知识。在托福阅读练习中大家要多找些托福文章练习，小编也会经常找些文章让大家参考的，下面开始今天的托福阅读吧。

　　对很多人来说，眼睛的颜色从生下来那一天开始就确定了，而且一辈子不变。但对另外一些人来说，却不是这样。究竟是什么原因会导致眼睛变色呢?

　　It can bend light， bring the world into focus， and next to the human brain may be our most complicated organ. But for many people the most intriguing feature of the human eye is simply its color.

　　Can it really change for no apparent reason?

　　In most people， the answer is no. Eye color fully matures in infancy and remains the same for life. But in a small percentage of adults， eye color can naturally become either noticeably darkerorlighter with age.

　　What determines eye color is the pigment melanin. Eyes that have a lot of it in the connective tissue at the front of the iris， called the stroma， are darker， while those that have less tend to be lighter.

　　The levels of melanin generally remain the same throughout life， but a few things can change them permanently.

　　The first is a handful of ocular diseases like pigmentary glaucoma. Another is a condition called heterochromia，ormulticolored eyes， which affects about 1 percent of the population and is often caused by traumatic injuries. An example of this can be seen in the rock star David Bowie， who attributes his contrasting eye colors， hazel and light blue， to a blow to the face as a child.

　　The third cause appears to be genetics. A study in 1997， for example， looked at thousands of twins and found that 10 percent to 15 percent of the subjects had gradual changes in eye color throughout adolescence and adulthood， which occurred at nearly identical rates in identical twins.

　　The bottom lines Eyes can change color in some people because of geneticsorinjury.

　　以上就是今天的托福阅读材料，每天做几篇阅读，坚持下来，一定会有不小的进步，阅读的同时不要忘记，积累陌生词汇与优秀的句子，以便考试的时候能派上用场，英语不是一朝一夕的事，所以大家一定要勤加练习。