Ray-Ban Erika Metal 0RB3539 002/Q4

The amount of the Sphere refers to Far Vision (Myopia “-”) or to Near Vision (Hyperopia “+”). It can appear in the prescription with the abbreviation SPH. Don´t forget to check the sign.

The amount of the Cylinder refers to Astigmatism. It can appear in the prescription with the abbreviation CYL. If it doesn´t appear in your prescription, leave “- -“ which is by default.

The amount of the Axis refers to the Cylinder position. This is between 0 and 180º. It can appear in the prescription with the abbreviation a. if it doesn´t appear in your prescription, leave “- -” which is by default.

It can be expressed with Nasopupilar Distance (NPD) or Interpupilar Distance (IPD). The NPD is the distance from each pupil to the nose and in the prescription, you will find 2 results (equal or different), one for each eye (Ex: NPD Right Eye: 29; NPD Left Eye: 31). On the other hand, the IPD is the distance between the two pupils and in the prescription you are going to see only one number. In this case, you have to divide the value IPD between 2 (Ex: IPD 60 NPD Right Eye = 30; IPD Left Eye 30).

The amount of the Sphere refers to Far Vision (Myopia “-”) or to Near Vision (Hyperopia “+”). It can appear in the prescription with the abbreviation SPH. Don´t forget to check the sign.

The amount of the Cylinder refers to Astigmatism. It can appear in the prescription with the abbreviation CYL. If it doesn´t appear in your prescription, leave “- -“ which is by default.

The amount of the Axis refers to the Cylinder position. This is between 0 and 180º. It can appear in the prescription with the abbreviation a. if it doesn´t appear in your prescription, leave “- -” which is by default.

It can be expressed with Nasopupilar Distance (NPD) or Interpupilar Distance (IPD). The NPD is the distance from each pupil to the nose and in the prescription, you will find 2 results (equal or different), one for each eye (Ex: NPD Right Eye: 29; NPD Left Eye: 31). On the other hand, the IPD is the distance between the two pupils and in the prescription you are going to see only one number. In this case, you have to divide the value IPD between 2 (Ex: IPD 60 NPD Right Eye = 30; IPD Left Eye 30).