If a patient has perfect eyes, then distance objects are sharp and perfectly clear when their eyes are completely rested and totally relaxed. When they want to see something closer, that patient uses the ciliary muscle inside the eye to change the shape of the lens inside the eye to focus the eyes on the near object. Unfortunately, as we accumulate birthdays, the lens inside the eye becomes more and more rigid, and less flexible. This process is called presbyopia. With time, the lens inside the eye loses enough elasticity and becomes so hard that the ciliary muscles can no longer change it's shape. Eventually, near vision becomes blurry. Some patients experience strain, tiredness and headache as an early symptom of this process. In either case, the Optometrist can make precise measurements and prescribe just enough lens prescription to do the work that the eyes can no longer do on their own, and make the vision clear and comfortable again. The simplest lens prescription to correct presbyopia is a simple pair of prescription reading glasses. If a patient also has nearsightedness, or farsightedness or has astigmatism, that patient may prefer to wear bifocals or progressive lenses for convenience.