How to Read the Eyeglasses Prescription?
The forms of the eyeglasses prescription are in a great variety, but the basic items are the same such as name, occupation, sex, age, and so on.
To place an order, you need to have at least a prescription for a corrective eyeglass lens and your pupillary distance. If you have a prescription for a contact lens, it may not be used to make eyeglasses.
The most important items are the nature of the sphere lens, the diopter, the axial position, the refraction degree of the column lens, uncorrected visual acuity of the right and left eyes, corrected visual acuity as well as the pupil distance.
Now I would like to teach you the meaning of the marks in the prescription form.
OS / LE / L : left eye
OD / RE / R : right eye
+ : Convex lens ( for the hypermetropia )
–: Concave lens （for myopia）
After “ +” or“ –”, the Arabic value is lens’ diopter, but what needs to pay attention to is that diopter in the prescription glasses and the strength are not the same, a difference of 100 times between them, for instance, – 1.00D is equal to 100 degrees which we usually say;
DS: Spherical lens （both for hyperopia and myopia ）
DC: Cylindrical lens ( for astigmatism )
Behind DS, there is a mark “()”, representing the spherical lens “United” the following the cylindrical lens; at the back of DC, there is also a mark “×”, separating the front degree of astigmatism from the behind the astigmatic lens axis （1～180°）;
PD: pupil distance
Ｒ：—2.OO DS () — 2.OO DC × 90°
It stands for right eye，200 degrees of myopia with 200 degrees of astigmatism, degree of astigmatism axis is 90 °, the pupil distance is 63 millimeters.
When you have your eyes examined, request the PD of the person who does your exam, since a corrected lens cannot be made without it. It’s used to position the optical center of the lens so that you will be able to easily see through the lens, to center the correction in front of the pupil of your eye, in the eyeglasses. Therefore, you cannot alter your PD simply to have it match the specifications of a frame that you might want (which will not accept your PD), because you will not be able to see through a lens produced from incorrect information.
The correct PD is particularly important for a multi-focal lens, as multiple viewing fields are adjusted based on the PD supplied.
It is frequently left off the prescription (although it’s usually recorded in your file), since having your PD empowers you to purchase eyeglasses from any supplier, not necessarily with the office of the person who does the exam.
PDs may be indicated in a variety of ways – You might be given numbers such as 63/60. This would mean that you use 63 as your PD for single vision distance, or a multi-focal pair of glasses. The smaller number would be used only when converting the prescription to single-vision reading glasses. You may be given fractional PD measurements, right side and left side, and split PDs may be written as 30.5/31, for example.
Single vision computer glasses – Split the Add number in half, and combine that split number, with the Sph. Discard the remaining Add, and leave the Add data entry field blank. Use the distance PD, unless your monitor is virtually in front of your face, in which case, you may wish to narrow the PD a millimeter or two, for the sharpest focus.
Single vision reading glasses – Combine the Add and Sph numbers. In the case of the Positive Add and a negative Sph, net the difference, and the new number becomes the Sph. The Add data entry field will be blank, by it having been combined with the Sph number. If your Sph is already positive, you simply combine the positive Sph and the Add number, using it for the new Sph. The Add data entry field will be blank. For single-vision reading only, you narrow the PD by 3mm from the distance vision PD.
Multi-focal Computer/Desktop glasses – To create this modification, you simply split the Add number in half (if there is no equal division of the Add number, you’ll need to decide if you want your focus closer or further, and the quarter diopter difference will shift the depth of the focal plane, accordingly) and combine half of the Add with the Sph. The balance of the Add will stay in that data entry field. Note: We do not create a multi-focal lens with an Add of less than +1.00. Use your distance PD, unless your monitor is extremely close (less than 18”), in which case, you may wish to narrow the PD by a millimeter or two.
Multi-focal prescriptions may be modified for single vision use, or even a different multi-focal use, by working with the Sph and Add numbers. If there is a correction for astigmatism in one eye, or both eyes, those designations will not change, regardless of the depth of the focal field.
Single vision distance only – leave off the Add number and use the larger of the PD numbers if you’ve been given two.