How to read glasses prescriptions
The Glasses Ordinance (Explanation of Values)
You get a prescription for glasses if the ophthalmologist determines during an eye examination that you have refractive ametropia, which can and should be corrected with glasses or contact lenses. The prescription for glasses is, so to speak, the "prescription" for glasses and can only be issued by an ophthalmologist's practice (not by an optician).
First, the official model of such a prescription for glasses:
Here you will find files to download and print out:
What do the abbreviations of the glasses regulation mean?
The glasses regulation is divided into two areas. In the upper area, personal data is recorded as well as questions about previous glasses and the reason for the visit to the doctor.
The lower area contains the values that are required to be able to produce a visual aid (glasses or contact lenses). The lens can be manufactured precisely on the basis of this data. In the Glasses Ordinance, the information and abbreviations are standardized so that they are given uniformly by all ophthalmologists.
This is what the abbreviations mean:
- Anyone who is nearsighted needs distance glasses (F.), those who are farsighted need close-up glasses (N). Since this information can also be read from the following diopter number, it is often omitted.
- "R."shows the data for the right eye, "L." for the left eye.
- Sphere stands for "sphere". This describes the degree of bulge required to regain normal vision. The unit for this is dioptre, the values are divided into 0.25 steps. Negative values indicate nearsightedness, positive values indicate farsightedness.
- Cyl is the abbreviation of cylinder. This information is only recorded in the glasses passport if there is astigmatism - mostly as a result of astigmatism. This means that the cornea is not evenly curved, but rather has a kind of dent in one direction. This special form of ametropia can be (mathematically) described with the shape of a cylinder. Here, too, the unit stated is dioptre.
- The axis is also only relevant in the case of astigmatism. The value describes the direction in which the curvature is present. The axis position supplements or concretises the aforementioned cylinder value. The number mentioned refers to an angle on a circle (0 ° is vertical, 90 ° horizontal). The two semicircles below with the angular degrees basically show the same thing.
- The value Prism (for prism) indicates whether there is an ametropia (very slight squint). If so, the lens must be slightly prismatic.
- Base (B.) in this case shows the basic position of the prism horizontally (h) and vertically (v) - unit "degree" with integer values between 0 ° and 360 °, sometimes just "inside" (i), "outside" (a ), "Above" (o) or "below" (u).
- The vertex distance shows the distance at which the values of the prismatic spectacle lens were measured during the examination (distance from the foremost point of the cornea (vertex) to the spectacle lens). The prismatic power of the lens must be adjusted depending on which model of glasses you choose later - and how big the exact distance between the vertices is.
In contrast to the glasses passport, which is sometimes given by an optician, two values are missing:
- Add denotes the addition. This number is only relevant for varifocal glasses. It is used to describe the range in which the poor eyesight moves between nearsighted and farsighted. This usually comes into play when myopia is accompanied by presbyopia.
- PD is the abbreviation for pupillary distance. This very important value should definitely not be missing in the glasses passport. The two values indicate the distance between the pupil (with normal "looking straight ahead") and the center of the nose in millimeters. The pupillary distance is very important for a good visual impression. Because the glasses always have an "optimal" point, which should be as exactly as possible in front of the pupil. If the pupillary distance is shifted by a few millimeters, this can lead to headaches and a blurry image in the long run. You should therefore not simply use someone else's glasses, even if they have the same diopter values. And for this reason, buying reading glasses in the supermarket is not advisable. You can determine the pupillary distance yourself with a printed out, but it is always more precise to have the value determined by an ophthalmologist or optician.
What does the prescription for glasses cost?
Normally, the costs for the eye examination are covered by the health insurance. This is especially true if the visual acuity has changed by more than 0.5 diopters (since the last eye examination). Otherwise, you have to ask the ophthalmologist directly about the cost of re-issuing the prescription for glasses.
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