Prescription

HOW TO READ ONE’S PRESCRIPTION


You can find all the information regarding your contact lenses on your prescription or on your old lens case.

All contact lenses have basic parameters:

Diameter: contact lens diameter in mm. If there is no choice in diameter for a certain type of lens it means there is only one standard value.

Base curve: the curvature radius is the radius in mm of the sphere at the back of the lens, i.e. the surface in contact with the eye. Typical values range between 8.0 and 10.0mm.

Power: correction power in dioptrics. For hypermetropia (long sighted) one requires positive converging power (e.g. +4.00D) while for myopia (short sighted) one requires negative divergent power (e.g. -4.00D).

The (toric) lenses to correct astigmatism (deformed vision) may have additional features:

Axis: position of the cylinder in the lens in degrees (0° to 180°).
Cylinder: astigmatism correction as expressed in dioptrics.


EXAMPLES


Exemple 1 In this case you will have :
Power PWR: -4.75 (myopia)
Radius BC: 8.4mm
Diameter: 14.2mm
Exemple 2 In this case you will have :
Power PWR: -1.25 (myopia)
Radius BC: 8.6mm
Diameter: 13.8mm
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