Myopia is said to be caused by an elongation of the eyeball. This means that the oblong (as opposed to normal spherical) shape of the myopic eye causes the cornea and lens to focus at a point in front of the retina.
1 Bonds pay interest every six months until they mature. When a bond matures, the owner is paid the face value of the bond. 2  Bonds can be held until maturity or sold before maturity.  More about Treasury bonds rates and terms in the Research Center.
Bills are sold at a discount from their face value. Treasury notes are government securities that are issued with maturities of 2, 3, 5, 7, and 10 years and pay interest every six months. Treasury bonds pay interest every six months and mature in 30 years.