Regular eye exams are an important in your eyes healthy and your vision sharp. We recommend to get your eye check-up done annually.
You have just been to optometrist or ophthalmologist (an eye doctor) and got a prescription for your spectacles. Though it might be difficult to understand the prescription, here is description of some common terms.
OD: OD means Oculus Dexter or Right Eye. Some doctors even write R.E.
OS: OE means Oculus Sinister or Left Eye. Some doctors even write L.E.
OU: OU means Oculus Uterque or both Eyes.
NV: NV stands for Near Vision
DV: DV stands for Distant Vision
SPH (Sphere): Sphere indicates the lens power which is measured in diopters (D), prescribed to correct nearsightedness or farsightedness. If the number appearing under this heading has a minus sign (–), you are nearsighted; if the number has a plus sign (+) or no sign then you are farsighted.
CYL (Cylinder): Cylinder indicates the lens power for astigmatism. Astigmatism is a type of refractive error caused by an irregularly shaped cornea. Instead of cornea being round it is slightly oval, causing vision to be blurred or distorted to some degree at all distance.
If nothing appears in this column, either you have no astigmatism, or your astigmatism is so slight that it is not really necessary to correct it with your eyeglass lenses.
The number in the cylinder column is preceded with a minus sign or a plus sign for correction of nearsighted or farsignted astigmatism respectively. Cylinder power is always written after sphere power in the prescription.
Add: Add is the added magnifying power applied to the bottom part of multifocal lenses to correct presbyopia. Presbyopia is the normal loss of near focusing ability that occurs with age. Most people begin to notice the effects of presbyopia sometime after age 40, when they start having trouble seeing small print clearly — including text messages on their phone. The number appearing in this section of the prescription is always a "plus" power, even if it is not preceded by a plus sign.
Prism: This is the amount of prismatic power, measured in prism diopters ("p.d." or a superscript triangle when written freehand), prescribed to compensate for eye alignment problems. Only a small percentage of eyeglass prescriptions include prism.
PD: PD is the distance between the centres of your pupils in both eyes. It’s used to ensure that your prescription is correctly centred in your eyeglass lenses.