When you look closely at your presciption for eyeglasses, you will notice numbers listed under OD and OS headings. These are Latin abbreviations for right eye (oculus dexter, OD) and left eye (oculus sinister, OS). Occasionally you will see the notation for OU (oculi uterque), which means both eyes, right and left.

The further away from zero the number on your presciption is, the worse your eyesight and the stronger the correction needed. A plus sign (+) in front of the numbers means you are hyperopic, or farsighted. A minus (-) sign means you are myopic, or nearsighted. The numbers are recorded in diopters and is often abbreviated as D. The least amont of correction your doctor will prescribe is a 12th (.12) of a diopter, like $0.12 of a dollar. For example, If your prescription states -1.00, you have one diopter of nearsightedness, or a correction similiar to one dollar. This would be a mild amount of nearsightedness. If you are -5.00, you have 5 diopters of nearsightedness or an equivalence similiar to $5.00. This would be more nearsightedness, and would require much stronger lenses. Similiarly, +1.00 would be a small amount of farsightedness and +5.00 would be much more.

If your eye is astigmatic (two different corneal curves), there will be three numbers in your prescription, sphere, cylinder, and axis. The sphere portion reveals how much nearsighted or farsighted correction is needed, as discussed above. The cylinder reveals how much astigmatism correction is needed. The axis determines at what degree the the cylinder correction should be placed.

The add power, or bifocal power, is the amount of additional correction that is needed for close up, or near vision. This is always found in multifocal lenses.

The further away from zero the number on your presciption is, the worse your eyesight and the stronger the correction needed. A plus sign (+) in front of the numbers means you are hyperopic, or farsighted. A minus (-) sign means you are myopic, or nearsighted. The numbers are recorded in diopters and is often abbreviated as D. The least amont of correction your doctor will prescribe is a 12th (.12) of a diopter, like $0.12 of a dollar. For example, If your prescription states -1.00, you have one diopter of nearsightedness, or a correction similiar to one dollar. This would be a mild amount of nearsightedness. If you are -5.00, you have 5 diopters of nearsightedness or an equivalence similiar to $5.00. This would be more nearsightedness, and would require much stronger lenses. Similiarly, +1.00 would be a small amount of farsightedness and +5.00 would be much more.

If your eye is astigmatic (two different corneal curves), there will be three numbers in your prescription, sphere, cylinder, and axis. The sphere portion reveals how much nearsighted or farsighted correction is needed, as discussed above. The cylinder reveals how much astigmatism correction is needed. The axis determines at what degree the the cylinder correction should be placed.

The add power, or bifocal power, is the amount of additional correction that is needed for close up, or near vision. This is always found in multifocal lenses.