PROGRESSIVE LENSES AND PRESBYOPIA
While all of us would like to feel eternally young, when we reach age 40 or so the need for the dreaded “B” word (bifocal) will eventually be broached by your eye care practitioner. Line bifocals go all the way back to Benjamin Franklin. These allow you to focus from distance to near without having to take glasses on and off or to remove glasses to focus at one distance or the other.
The reading need begins around age 40 give or take a few years one way or the other. It gradually changes and increases over about a five to seven year period and then stabilizes out. This is caused by a gradual change in the ability of the crystalline lens inside of the eye to change shape. This changing in shape allows one to focus from distance to near and back. Tiny attachments to the lens called zonules gradually lose their abilty to cause the lens to change shape and hence to allow focusing at different distances. This is a natural maturing (aging) change and will happen to all of us.
As a member of the baby boomer generation I recognize the yearning to resist crossing over to this dark side of aging, but alas there is nothing that we can do about it. In light of this fact then let us go with the best type of correction for this condition. While line bifocals were OK many years ago, in today’s computer using society these are not very ergonomically practical. The distance portion gives great distance acuity and the reading portion gives great reading at book and magazine distances. However, the computer distance (usually approximately 20-24 inches) becomes a complete blur or at the very least very difficult to see without getting closer to the screen and then craning one’s neck and causing all kinds of neck and shoulder pain.
This then brings us to our discussion of progressive lenses also known as no line bifocals. These lenses have been around for over 20 years and have gone through a number of generations. Each new change in technology has gotten better and better such that the newest lenses work quite well for most people. While the earlier generations of these lenses are still available and are less expensive they also carry with them the inherent problems and side effects of those earlier generations.
The earlier generations have narrow reading areas, peripheral distortions and hard to find intermediate distances. Either you or someone you know may have tried one of these earlier types of progressives and could not get used to them. This is certainly understandable with these earlier lens designs. They unfortunately are still sold on a regular basis many times because they are cheaper.
Come on people, this is your sight. This is how you make your living. Don’t be cheap when it comes to correcting your vision properly! This now brings us to the point in the discussion of the newest generation of progressive lens technology. This newest generation has come about over about the last year or so. There are several companies that have come out with their own version of these new lenses. You may hear the buzz phrase of “digital surfacing” bandied about in conjunction with these new lenses.
Bear in mind that digital surfacing is just a manufacturing technique as opposed to a lens design. Digital surfacing simply means that it can reproduce any lens design perfectly time after time even if it is an older lens design. Don’t be confused between ‘lens design’ and ‘digital surfacing’. I have tried all of these new lens designs. To be perfectly honest I did not think that I would notice much of a difference before I tried the first one. I am happy to report that I was pleasantly surprised and shocked at what a huge difference there is in these new lenses from everything that we have had in the past. This is a giant leap in technology.
A good comparison in layman’s terms would be the difference between a regular TV and an HD TV. Everything is clearer and sharper. Contrast sensitivity is improved therefore making night driving easier and better. Wider reading and intermediate areas are found and larger depth of field can be seen. Almost immediate adaptation occurs from patient feedback. We have patients in our office who could not adapt to any of the earlier generations and wore two separate pairs of glasses. I convinced them to give these new lenses a try and we have not had one single non adapt. As eye care physicians, we owe it to our patients to not only educate our patients but to promote these newer lenses. We are not doing our patients a favor by continuing to offer only the ‘older 14 year old technology’ simply because we do so out of habit or we can’t get our opticians out of the habit. We owe it to our patients to offer the absolutely very best that is on the market today.
Brand names for these newer lenses are as follows: