Do you really understand your optical prescription?
It has never been so easy!!
An optical prescription may vary depending on the formatting and the country we are. However, they are more or less universal . Most doctors use a similar process to graduate your vision and create the prescription. It is necessary that your report is less than two years old and your optician or ophthalmologist is required to provide you with a copy of your graduation without any extra charge .
The optical prescription is divided into right (OD) and left eye (OS) and now we’re going to reveal all its secrets.
The sphere ( Sph / EsF )
Specifies the force that your lenses need to have for correcting your vision: a positive sign (+ ) indicates that we need to correct farsightedness ( hyperopia = difficulty focusing on nearby objects ) and a negative sign (-) means that you have to correct nearsightedness (myopia = trouble focus on distant objects). The numerical values indicates the number of correction you need for each problem , the higher the number, the thicker your lenses.
The cylinder (CYL / CYL )
Indicates necessary dioptres to correct astigmatism . We can find this in your optical prescription usually named as Cylinder CYL or Clylinder . The cylinder can have a positive or a negative sign (never mixed). The CYL also comes along with a value for the Axis or Axis (indicates the inclination of the eye) a number between 1 and 180. If these values do not appear in your optical prescription , just leave spaces empty.
The sum (near / ADD)
It is very common to use glasses for reading, it´s well known as near vision (aka reading glasses ) for that we use multi focal lenses (progressive/bifocal ) .
We use the parameter: Sphere or spherical near power . This value can also be positive or negative. The Adding value is obtained as a result of this subtraction :
Adding = sphere far – near sphere
The pupillary distance ( PD)
The pupillary distance (PD ) is the distance from the center of the pupil (black circle) in one eye to the center of the pupil in the other. This measure is essential to focus the power of lenses and if it is not written in the recipe , you can ask your optician this information, ask for help from a friend or do it yourself with the help of a mirror and a ruler.
Here ‘s how:
Place the millimetre ruler on the bridge of the nose.
Ask someone who makes himself a half meters away in front of you and measure with ruler the distance between the centres of the pupils (the black circle in your eyes) .
Here you have a rough guide to average values for orientation:
Adults – typical values move between this range: from mm 56mm to 66mm.
Children – Typical children’s values usually range: from 41 mm to 55 mm.
Now that you know how to make it…go for it : )