subject: What does prescription lenses mean? [print this page] What does prescription lenses mean? What does prescription lenses mean?
If during the examination of the eye, a patient is found to require glasses, they will usually be given a prescription after the test. This prescription is then used to make a pair of prescription glasses for the patient.
A prescription lists the parameters, or specifications of the prescription lenses. It will also list the specific state of both eyes, noting aspects such as the strength of both distance and near vision in both eyes, any refractive errors, and the axis of the eye. An optometrist will also take note of the measurement of space between a patients pupils, and the space between the glasses lens and the cornea.
Although the prescription is given to both the patient and the optician, it is written in abbreviated form on a chart which can often be hard for someone untrained to understand. The abbreviations include OD, OS, SPH, CYL, PRISM and ADD
OD stands for oculus dexter, latin for right eye.
OS means oculus sinister, left eye
SPH stands for sphere and indicates the measurements of the horizontal curve of the eye, which determines the strength of lens required.
CYL or cylinder lists the vertical curve of the eye lens.
PRISM is a measurement used only for those requiring a more complex prescription.
ADD is a measurement used in prescriptions for bifocal lenses. It indicates the amount of power that is needed.
This information is found by an optometrist during a series of tests, and is used in creating a prescription. This prescription is given to an optician who gives the correct prescription eyewear to the patient.
