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.
Bonds ï® Usually issued in $1,000 or $5,000 denominations ï® Maturity runs from 15 to 25 years ï® Interest paid annually or semi-annually ï® Types ï¨ Serial âthe most widely used, principal comes due in installments ï¨ Term âprincipal comes due at a single point in time.