Eyeglass prescription meaning
Above are the sample of the prescription card format in which the prescription is mostly written so that an optician or optical dispenser would understand. Here are the terms which help to read eyeglasses prescription easily.
Eyeglass prescription terms
OD and OS
O.D means “Ocular Dexter” meaning Right Eye in Latin while O.S means “Ocular Sinister”.
SPH and CYL
The term SPH means spherical dioptric power while CYL means Cylindrical dioptric power. The cylindrical power has “AXIS” that ranges from 1º to 180º.
Prism is not commonly used in prescription except for the cases where the patient has a squinting problem. If the prism is present, base too should be mentioned. Distance means the power of the distance while near means power for near as our eye’s lens changes focal length from Distance to Near. The Near power when added to distance is termed as addition as shown in the above figure. Near power means, your glasses are bi-focal or progressive lenses. The presence of cylinder power means, you have astigmatism while spherical power denotes you have Myopia or Hypermetropia, Near power means you have Presbyopia or you are Pseudophakic (Artificial intraocular lens implant after cataract surgery).
Things that need to be considered while prescribing glasses
- Give careful consideration to whether the SPH and CYL are positive or negative.
- A typical single-vision eyeglasses prescription without astigmatism just needs the SPH. You will likewise require your Pupillary Distance (PD), which might be incorporated on your prescription as two numbers; add these numbers together and you have your PD. In the event that your Prescription does exclude your PD, you have a couple of alternatives. In the first place, you can contact your optometrist and they may give it to you. You can likewise go to a neighbourhood optician and have them measure it. Or on the other hand, you can quantify it yourself.
- On the off chance that a number isn’t in the CYL and eyeglass prescription AXIS spaces, there is no value for either.
- You will just have an ADD measure in the event that you wear bifocals/progressives.
- SPH, CYL, and ADD are composed of decimals. In some cases there is no decimal focuses on the prescription. You at that point get the opportunity to include them in. (Case: an SPH composed as “175” is “1.75” and an ADD composed as “25” would be “2.50.”)
- Once in a while, the prescription won’t be written on a genuine network. The numbers will be that as it may likely be composed by the framework appeared, with OD to finish everything, OS on base, with segments SPH, CYL, AXIS, and so forth.
- On the off chance that you see the word PLANO in the line of boxes for one eye, you require a “balance lens” for that eye. A balance lens is a non-prescription lens; you require one if just a single of your eyes requires vision correction.
- Last, however not minimum, if both of your eyes have a similar correction, just a single line of numbers might be your Prescription composed of.
If you want to wear a Contact lens your optometrist also helps you converting an eyeglass prescription to a contact lens.