An easy way to sell lenses without lengthy explanations is to present pictures or videos made by the lens manufacturers, but this often leads customers paying for the most premium lenses even though they may not need them.
The latest free-form technology in lens surfacing is most recommended for all multifocal lens users. While all lens manufacturers compete in advertising new complex designs, customers will hear only of advantages hardly ever finding out about adverse outcomes of getting something that they do not need.
X Never trust these images X
How to select lens designs?
First of all, do not trust these pictures, these marketing medias are made for sale persons to sell easily without explanation, optometrists would not use them as they are not real images and also not related to the required prescriptions.
When the long distance and reading additional power are low, especially in a new user aged 40-46, having a moderate or standard design should be good enough. The residue distortion is very little, paying more money for expensive advanced design will not make an noticeable difference. This group of buyer often pays for something they do not actually need by relying on convincing media advertising only.
The advanced designs are made to reduce distortion in high powers. When the distance, astigmatism, and reading additional power are higher, an advanced design is an alternative option.
People with bad experience wearing multifocal lens usually have binocular vision problems or high astigmatism in different meridians need minor adjustments, optometrists can specify some parameters added to any lens design to improve the comfort and widen reading field. This group of buyer were often convinced to buy custom design instead which does not solve the problem.
All lens designs mentioned above can be ordered according to purpose of use. Customers should always specify their reading requirements as the proportion of the distance, intermediate and reading part can be changed to fit individual needs.
Most important thing to know is that all multifocal lenses are produced according to factory predetermined set-up parameters, if the optical frames have standard parameters when sitting on the face e.g. curve, pantoscopic tilt angle, and vertex distance, there is no need to pay for more expensive lens than standard or advanced design.
So, when do we go for the most expensive custom design?
To order custom designs, optometrists need to check measurements of frame parameters when sitting on the face, so it is not made according the the initial factory set-up. This is good when the frames are not in ordinary curve range. This design is not invented to widen reading area in the common-shape frames but to solve the problem in extraordinary ones. Most of the lens manufacturers name it as “high-end quality” surely to top up the selling price. In addition, this custom design should be prescribed by a qualified optometrist who has lots of expertise, all measured parameters must be precisely corrected otherwise the result can be upside down.
What is an adverse outcome of the expensive custom design?
When having standard or advanced design, the digital surfacing is made only on the back side. However the frames sit, either a little too low or too high, the wearer can still get full range of the reading field. But in custom design there is surfacing on both surfaces, if the frames sit little too low or too high, the wearer can get all reading area only from the back but miss some part of the front surface. It will be more critical in thicker lens when back and front is far apart. To get the best outcome from it is to wear the glasses all the time at the initial designed position.
In conclusion, when shopping for a pair of progressive eyeglasses, always ask an optometrist for the factory initial set-up frames parameters and look for ideal ones by checking the parameters when wearing on the faces. The same frames on different faces turn out to different parameters, that is why ordering online is not recommended. If the parameters of the chosen frames are not within that range, consult an optometrist if it’s worth taking a custom designed lens. The more complex design requires more balance control on the nose and ear positions.
There is another tip to choose the frames, it is recommended to have frames that sit firmly, height not less than 25 mm. but more than 28 mm. is preferable. The eye position is very important, it cannot be too low or high. In any frames size, when dividing them into 3 equal parts horizontally, by looking in the mirror the eye’s position should be very close to or exactly at the upper dividing line.
The key to success is: choosing proper frames, specifying individual needs, having a binocular vision test and precise measurement of pupillary distance (PD). In case there is binocular vision problem or the eye height position between both eyes are very different, some minor options added in any design would be more reasonable and ethical than being convinced to pay double or triple price for a hi-end fancy design.