What you need to know before buying contact lenses

And they must be selected by an ophthalmologist – he will check your eyesight and write you a prescription for contact lenses. In optics and contact correction salons there is a fitting service, ask about it. According to the recipe, knowing the parameters, you can buy them, including in online store or lensomat, without the participation of a consultant.

Next time for a prescription and recommendations from a contactologist, come back if you want to change them. As a rule, if during the process of wearing you realize that the lenses are uncomfortable for you, then a second appointment will be free. Although in many salons, an eye test and an initial prescription will also be free, subject to purchase. Specify this point when choosing a salon.

When you need to visit an ophthalmologist-contactologist again

  • If you want to change brands, especially when switching from hydrogel to silicone hydrogel or vice versa, and if you want to change the wearing mode.
  • In case that you have discomfort, visual discomfort.
  • For a scheduled inspection 1 time / year.

What is written in the prescription for contact lenses

The prescription will indicate the parameters for each eye: optical power in diopters, radius of curvature and diameter. Here is how all these parameters are indicated:

 Sph (Sphere) Optical Power   BC, R Curvature Radius   DIA, D Diameter 
 OD (Right Eye) 

 OS (Left Eye) 

How to decipher a prescription for contact lenses

Optical power – sphere (sph). It is measured in diopters, and their value will be written in a positive or negative value ("+" or "–"). The value is a number with one or two digits after the decimal point, such as +1.5 or –3.75.

Means the strength of the contact lens, in terms of meaning, this is the same parameter as for glasses. Since contact correction is more effective than spectacle correction, the optical power will also be lower than that of glasses. It is specified as a number with one or two decimal places followed by a "+" or "–" sign. Please note that the optical power for the right and left eyes may be different, in which case you will need different packages for each eye. If you have presbyopia and use multifocal lenses, each eye will have two readings for each eye, one for near and one for distance.

The base curvature radius (BC, R) is an indicator of the inner surface of a contact lens that is in direct contact with the cornea of ​​​​the eye, so their fit on the eyes will depend on it. This is very important, because if it is incorrectly selected, the lenses will put pressure on the cornea and not only cause discomfort when worn, but also affect the production of tears, which means inflammation and eye diseases. The usual value is from 8.3 to 8.7, the most common BC is 8.6. Please note that different manufacturers may have different ones, so when changing the brand, you need to contact an ophthalmologist.

Since this indicator depends on the curvature of the cornea of ​​the eye, as a rule, it is the same for both eyes.

Diameter (DIA, D) is the size of the contact lens, measured from one edge to the other through the center. Depends on the parameters of the eye and is usually the same for both eyes. Denoted by a number with one digit after the decimal point: for soft contact lenses, it usually has a value between 13.0 and 15.0.

Even if you successfully wear contact lenses, do not forget to visit an ophthalmologist once a year to check your eye health. At the slightest discomfort, contact a contactologist.

Toric lens options

For astigmatic toric contact lenses, additional parameters must be specified in the prescription: axis and cylinder.

Cylinder(CYL) is the optical power of astigmatism. In the recipe, the cylinder will be indicated with a "–" sign. It usually has values ​​between –0.75 and –1.25.

Axis (Ax) is the angle of the astigmatism, measured in degrees. Typically has a range of 90° to 180°.

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