Understanding Your Prescription
Single Vision Prescription
Single Vision Prescription corrects for Distance only.
Progressive Prescription corrects Distance and reading, also known as mulitfocal lenses or no-line Bi-focal.
Prescription - the Numbers
The three basic measurements that we need to fill your prescription are Sphere, Cylinder, and PD (Pupilary Distance).
PD is not usually written on your prescription, but is a measurement taken by the optician filling the prescription. If you don't have this, check with the last lab that made your glasses.
Your prescription may look something like this example:
OD denotes Right eye.
OS denotes Left eye.
To determine the Total Power Take the sum of your Sphere and Cylinder for each eye.
OD (-0.25) + (-0.75) = -1.00 Total Power
OS (-0.75) + (-3.00) = -3.75 Total Power
Example 1: contains a plus Sphere and a plus cylinder. +2.50 +0.50; Add the pluses together and change the sign of the cylinder. +2.50 +0.50 when transposed is equivalent to +3.00 -0.50; Next add the plus sphere power to the cylinder power. This makes the Total Power +2.50.
Example 2: contains a plus sphere and a minus cylinder. +3.00 -0.50; Algebraically add the cylinder to the sphere. +3.00 -0.50; This makes the Total Power +2.50
Example 3: contains a minus sphere and plus cylinder. -2.50 +0.50; Algrebraically add the cylinder to the sphere and change the cylinder sign to a minus. -2.50 +0.50 when transposed is equivalent to -2.00 -0.50; Add the minus sphere power to the minus cylinder power. This makes the Total Power -2.50
Example 4: contains a minus sphere and a minus cylinder. -2.50 -0.50; Add the minus sphere to the minus cylinder; This makes the Total Power -3.00
To place your prescription order we must have a copy of your current prescription (no more than two years old) including your PD (pupil distance) measurement. This can be sent via fax or scan/ email. 541-388-0391 or firstname.lastname@example.org