Guide

How to read an eyeglass prescription

prescrizione

How to read an eyeglass prescription: Have you ever wondered what all the items on the eyeglass prescription issued by the specialist indicate?
Once the eye examination has been completed, no doubt when you read the prescription left by the optician you may have wondered what the indicated values mean.

In particular, you may have asked yourself some questions especially about the type of eyeglasses that turn out to be right for you. In addition, among the main questions that arise once you have obtained a prescription for glasses is the one inherent in the visual problem you are subject to and need to solve.

Eye problems can be many, the best known of which include: farsightedness, presbyopia, nearsightedness, and astigmatism. To understand which of these visual disorders you are prone to, it is essential to perform an eye examination.

At okvista's physical stores you can set up your appointment with the optician who will help you better understand your eye problem in detail in order to find the best solution based on your needs and characteristics.

Visual disturbances

Before showing you what the values in the prescription indicate, it is important to know the more general vision-related disorders, specifically there are:

    • Presbyopia: detects the slow loss of the ability to focus on objects up close and is in most cases caused by aging;
    • Nearsightedness: follows real complexities in focusing on images and objects that are distant, specifically optical vision appears blurry and blurred in divergences and distances;
    • Astigmatism: is a visual disorder that makes vision less clear and sharp, as it involves focusing light in multiple parts of the retina;
    • Hypermetropia: Leads problems in visualizing objects and environments up close. In detail, it makes both distance and near focusing complicated, depending on the accommodation of neck muscles and diopters.

These problems, just mentioned, are especially known as refractive errors, which serve especially when the eyes are hindered and face real difficulties in focusing light, as this step does not take place exactly.

The significance of these annoyances is depicted in the prescription issued by the ophthalmologist after performing the eye examination in a unit of measurement called diopter. In detail, diopters indicate the degree of adjustment essential to adjust the optics in the best possible way. In addition, it is good to know that in the more serious and severe cases of farsightedness or nearsightedness, the higher the diopter value specified on the eyeglass prescription will be.

Prescription for glasses: how to read it?

The prescription for spectacles in some cases may indicate certain terms including: Cylinder (Cil.), Axis (Ax.), Sphere (Sf.), Reading, Addition, Base, Prism and other items. Let us examine them together in their particularities:

    • Sphere (Sf.): this indication represents the correction power of the lens that has been recommended and chosen by the ophthalmologist to solve specific optical problems including hyperopia or myopia. It is calculated in diopters and is generally anticipated by the plus sign (+) for farsightedness in contrast to myopia, which is depicted the minus sign (-). The term Sphere is used for the resolution of these two optical problems because the correction is spherical.
    • Prism and Base: the first indication i.e., Prism, is the value that is used to make glasses for individuals experiencing visual problems such as double vision or strabismus. The latter deflects light in such a way that it reaches the retina of both eyes exactly. Once this process has occurred, the brain will act in order to bring both planned visions closer together on both retinas of the eyes by making one clear and sharp image. The direction of the prism is indicated through a precise note depicting the exact position of its base i.e., the largest margin or edge.
    • Right eye (OD) and left eye (OS): these two representations found in eyeglass prescriptions and also international, determine the difference in left and right eye measurements.
    • By distance: in the middle of the eye examination, the number 6/6 or 10/10 designates the distance at which the patient is placed with regard to the Tumbling E or Snellen tables used to calculate optical intensity. Such numbers generally mean that the patient's virus is perfect.
    • Cylinder (Cil.) and Axis (Ax.): the Axis and Cylinder represent the data concerning the correction of the visual problem known as astigmatism, where both are indispensable. In case there is nothing in the prescription lists inherent to these two criteru, it means that the patient is not affected by the problem of astigmatism. In the part of the column designated for the Cylinder, the value is preceded by the sign (-) i.e., negative regarding the resolution of the disorder known as myopic astigmatism and instead a positive sign (+) is depicted to indicate the presence of hypermetropic astigmatism.
    • For Reading (or Add. for Addition): specifically, this item reports ka correction that is needed in situations of near visual impairment. In particular, additional magnifying power is generally placed on the underlying verso of multifocal lenses to resolve and correct presbyopia. This criterion is depicted in every case with a positive sign, even in situations where the positive sign does not appear on the eyeglass prescription. The possible indications D and N signal the neutral, nondominant, or nondominant eye.
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