It has become commonplace for many consumers to purchase magnifying glasses or reading glasses at a commercial establishment; in fact, the consumer often trusts that the product he is purchasing meets the specifications stated on the label.
However, this is not always the case, and even if the product is purchased at a pharmacy or pharmacy, the power indicated on the package may not be what the lenses actually have. Manufacturers and distributors of such lenses are therefore required to perform laboratory testing on all batches in order to provide customers with greater assurance of quality.
According to the standard, what power should the label state?
The UNE-EN 14139 standard is called "Optics in Ophthalmology". Specs for Pre-Assembled Spectacles" – Indicates that pre-assembled spectacles need to have a power in the range of +1,00 to +3,50 diopters.
To comply with the regulations, lens manufacturers and distributors need to assure consumers that the potency stated on the label is the potency that the product really has, always taking into account the applicable tolerance margins specified in the EN ISO 8980-1 standard.
This type of glasses was manufactured with the Donders table in mind, which developed the normal accommodation curve at different ages after a study between certain age intervals and the loss of the ability to focus on objects A causal relationship is established up close.
The basis of this causal relationship lies in the loss of lens flexibility over the years. Magnifying glasses provide the ability to focus for presbyopic patients.
The Importance of Getting Lab Tests
As we said, the wattage indicated on the label does not always correspond to the actual wattage of pre-assembled spectacle lenses.
This can happen, among other factors, because during assembly the lens has been able to bend, and in doing so, has added a cylindrical component that changes the initial power of the lens.
Simple practices, such as standardized laboratory testing of all batches of product, increase the reliability of dealer brand offerings and restore quality assurance to consumers.
The table below shows the results of our lab tests, illustrating that the wattage obtained in the lab measurements differs from the wattage indicated on the label:
Other tests: measure the distance between optical centers.
There are other tests that can provide information on other possible deviations, such as measuring the distance between optical centers.
Therefore, laboratory testing to verify that the optical center of the lens has not shifted will prevent unwanted prismatic effects that impede vision.
