The Use of eye glasses
There is no denying that eye glasses are a common necessity in modern society. Many people like to wear them simply to function, even if they don't have the problems of nearsightedness or farsightedness.
To understand why we need glasses, it's important to know what happens when light enters our eyes. To be able to see properly we must adjust the total power of the eye so that it helps focus incoming and outgoing light beams on our retina – where the cones and rods are located. Our eyes are basically like very sensitive cameras. Ever wonder why the first thing we do after waking up is look around? It's to make sure our retinal have received enough light during the night to properly focus images on our brains.
The way to adjust our eye power is by wearing eye glasses: We change the power of our eye (or the curvature of the interior lens) until objects become clear and sharp. That's why it takes a while after putting on new glasses before one can see clearly – it takes some time for ones eyes to adjust and get used to these new glasses, just like when you get a new pair of contact lenses.