Ordering eyeglasses online may seem easy, but it is very different than ordering your average consumer item. It is important to know that opticians are university trained in the proper manufacturing, fitting, measurement, and dispensing of eyewear.
When ordering online, the untrained consumer is, in essence, taking on the role of a trained optical dispenser. This includes taking critical measurements and making critical decisions with respect to frame, lens and material selection. There is an inherent risk associated with making these determinations without the proper skills and education.
All consumers should be made aware that there are a number of factors that go into converting an eyeglass prescription into a quality optical device that provides clear, comfortable vision. These include:
- Proper measurement of your interpupillary distance (PD) at both distance and near focal points.
- Accurate measurement of the optical centres (OC) in order to avoid eyestrain and pulling.
- Determination of the most appropriate type and index of lenses given your prescription as well as work and lifestyle demands.
- Proper education and selection of tints and coatings for your lenses to best suit your lifestyle or work environment.
- Appropriate base curve determination.
- Proper selection of frame size, eye size, bridge width, temple length, shape, wrap, material, and overall fit to ensure good comfort and vision with minimal distortion and cosmetically acceptable lens thickness.
When you receive your glasses, a trained optical dispenser should ensure that they have been properly manufactured, are within acceptable tolerance, and fit your face correctly to ensure ideal vision. Poorly manufactured or poorly fitted glasses can cause eye strain, headaches, pulling, and blurred vision.
A September 2011 study found that 44.8% of eyewear ordered online FAILED at least one parameter of optical or impact testing. In addition, 28.6% were out of optical tolerance.