One of the unique features of the human eye is the ability to to change focus from distance to near. The process is called accommodation and was first theorized by Hermann von Helmholtz in 1855. With today’s imaging systems the process can actually be seen. Basically, the lens within the eye becomes more curved and the front of the lens moves forward to create a more powerful lens for near focus. For the science minded, go to http://bit.ly/1rbHuFd. to see the process of accommodation.