Your prescription, what does each parameter mean?
The first thing you need before buying a prescription glasses is to know your prescription. Both an ophthalmologist and an optometrist can examine you to determine what parameters should be applied to your prescription lenses (click here to know the process of prescription and visual examination).
Once you have your prescription with each specified parameter, you only have to indicate these when you make the purchase and we can prepare the glasses you need, but do you know what each of the sections in the prescription mean? The most common are the following:
- Interpupillary distance
- Addition (Progressive Glasses)
Sphere (SPH): It indicates the spherical power of the lens in diopters (D). The lenses are usually manufactured in one-quarter-diopter (0.25 D) increments. If your prescription shows a negative sign (-) in front of the value in diopters, the lens is concave and corrects myopia. The concave lenses are thicker at the edge and thinner at the center. If the sphere has a positive sign (+), then the lens is convex and corrects hyperopia. Convex lenses, unlike concave lenses, are thicker at the center and thinner at the edge.
Cylinder (CYL): It indicates the cylindrical power of the lens in diopters (D) and corrects the astigmatism. If you do not have astigmatism, nothing should appear in the sections Cylinder (CYL) and Axis (AXI) in your prescription.
Axis (AXI): Together with the cylinder, it completes the necessary values to correct the astigmatism in the lenses. Its values range from 0° to 180°.
Interpupillary distance (DIP): It is the distance from the center of the pupil of one eye to the center of the pupil of the other (values are usually around 56 mm - 69 mm). This parameter can also be indicated as pupillary distance, which is the distance between the center of the pupil of each eye and the center of the nose (normally it is about 28 mm - 34 mm).
Addition: This information will be in your prescription only if you have presbyopia or eyestrain. It is usually the same for both eyes and serves as a guide to know the necessary prescription and the ideal thickness of the lenses. At Visual-Click at the moment we do not offer progressive glasses, so this parameter does not appear in our form.
If in spite of everything you still have doubts about your prescription, do not hesitate to contact us. Our team of optometrists will be happy to answer all your questions.