INFORMATION FOR - General Public
What is an eyeglass prescription, a PD and a contact lens prescription?

An eyeglass (or optical) prescription is defined as the written record of the refractive error of the eye, including, if appropriate, reading add, prism and back vertex distance. Other eyeglass prescription specifications may also be included on the written copy as per the professional discretion of the prescribing optometrist. An eyeglass prescription can usually be arrived at and issued following a complete eye examination. In selected situations (such as fluctuating blood sugars, corneal infections, etc.); your optometrist may require additional testing to ensure the accuracy and stability of your refractive status before issuing an eyeglass prescription.  This is just one of the reasons for requiring a complete eye examination as compared to a stand-alone sight test before purchasing new eyeglasses.

A PD is a measurement of the distance between the centers of your two eyes. It is required when fabricating eyeglasses to ensure that your eyes are looking through the center of your lenses. Eyeglasses that are not set to your exact PD can cause headaches, eyestrain, blurred vision and/or double vision. The measurement of a PD is considered one of the required procedures for fabricating eyeglasses and not one of the procedures of an eye exam. The individual or company that supplies your eyeglasses is responsible for measuring your PD and ensuring that your finished glasses are fabricated to this measurement. In addition, this individual or company is also responsible for measuring the fitting height for multifocals, selecting and adjusting an appropriate frame, selecting an appropriate lens material and selecting an appropriate lens coating or tint. As noted above, all of these services should be performed by the individual or company you purchase your glasses from.

The specifications for purchasing contact lenses are different than the specifications for purchasing eyeglasses. In order to issue a contact lens prescription, additional specialized testing and a contact lens fitting must be performed after completing a complete eye examination. According to Section 5(3), Schedule 17 of the Health Professions Act, after completing all the services required to dispense contact lenses, regulated members must offer the patient a written copy of the specifications of the contact lenses. In addition, patients must be instructed in proper contact lens insertion/removal techniques, wearing schedules, lens cleaning regimens and replacement frequencies in order to ensure lifelong healthy eyes.

The Alberta College of Optometrists Guidelines to the Standards of Practice states that all optometrists must write the date of issue of the optical prescription or contact lens specifications, as well as the expiry date of the optical prescription or contact lens specifications, on the patient’s prescription form. The expiration date for optical prescriptions and contact lens specifications is left to the professional discretion of the optometrist based on the medical and/or visual condition of the patient.