Set of numbers specifying the refractive power needed in your glasses.

An eyeglass prescription has one, two or four components, depending on your prescription.

First the eye is specified (OD=right, OS=left).

Part 1 is the spherical correction (myopia or hyperopia). This tells you how near(short)sighted or far(long)sighted you are.

Parts 2 and 3 are the cylindrical correction and (if there is any cylindrical correction) the axis. This tells you if you have any astigmatism and if so, where it occurs.

Part 4 is a second lens power specifically for reading (only applicable to presbyopes).

There are various forms of notation for prescriptions; see internal links for more detailed discussion.

OD -5.00 -0.75 x 25 ADD 1.25

OS -4.50 -0.50 x 150 ADD 1.25

cylinder

refractive error

sphere

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Updated February 2005.