Vision Over 40

History of multifocal eyeglass lenses

Benjamin Franklin, the early American statesman and inventor, is credited with creating the first multifocal eyeglass lenses. Prior to Franklin’s invention, anyone with presbyopia had to carry two pairs of eyeglasses – one for seeing distant objects and one for seeing up close.

Sometime around 1780, Franklin cut two lenses in half (one with a distance correction and one with a correction for near) and glued them together, so the top half of the new lens enabled the wearer to see things far away and the bottom half helped them see up close.

This lens, with a line extending across the entire width of it, was first called the Franklin bifocal and later became known as the Executive bifocal.

Modern multifocal lenses

Bifocals. There have been many changes to bifocal eyeglass lenses since Franklin’s original design, making these two-power lenses thinner, lighter and more attractive. Today, the most popular bifocal for eyeglasses is called a flat-top (FT) or straight-top (ST) design. The part that contains the power for near vision is a D-shaped segment (or “seg”) in the lower half of the lens that is rotated 90 degrees so the flat part of the “D” faces upward.

FT or ST bifocals (sometimes also called a D-seg bifocals), are available in different-sized near segments. The most popular version sold in the United States has a near segment that is 28 millimeters wide, and is therefore called the ST-28 (or FT-28 or D-28) bifocal. This design offers a generous field of view for reading, yet keeps the near seg small enough to be cosmetically pleasing.

Other available bifocal designs include lenses with round near segments and bifocals where the near seg extends across the entire width of the lens (Executive bifocals).

All bifocals, however, have a limitation: Though they provide good vision for distance and near, they can leave the wearer’s intermediate vision (for distances at arm’s length) blurry. Which brings us to…

Trifocals. Trifocal eyeglass lenses have an additional ribbon-shaped lens segment immediately above the near seg for seeing objects in the intermediate zone of vision – approximately 18 to 24 inches away.

This intermediate segment provides 50% of the magnification of the near seg, making it perfect for computer use and for seeing your speedometer and other dashboard gauges when driving.

Trifocals are especially helpful for older presbyopes – those over age 50 – who have less depth of focus than younger presbyopes. (Younger presbyopes may still be able to see objects at arm’s length reasonably well through the top part of their bifocals.)

As with bifocals, the most popular trifocals have a flat-top (FT) design, with the near and intermediate segments being 28 mm wide. Trifocals with 35 mm wide segments are also popular.

Limitations of bifocals and trifocals

Although bifocals and trifocals are very functional, they pose a problem – the visible lines in the lenses. Most people prefer not to advertise their age by wearing multifocal eyeglass lenses with lines in them that everyone can see.

The lines in bifocals and trifocals cause a vision problem as well. Because they mark well-defined changes in power within the lenses, as the wearer’s eyes move past the lines, there is an abrupt change in how objects appear. This “image jump” can be difficult for some wearers to adapt to.

Some years ago, these limitations of conventional bifocals and trifocals led to a major breakthrough in multifocal eyeglass lens design: progressive lenses.

Progressive multifocal lenses

Progressive multifocal lenses (also called progressives, progressive addition lenses, and PALs) are true “multi-focal” lenses. Instead of having just two or three powers, progressives gradually change in power from the top to the bottom of the lens, offering a large number of powers for clear vision at all distances – distance, intermediate, near and everywhere in between.

And because there are no visible lines or abrupt changes of lens power in progressive lenses, there is no “image jump,” so the wearer’s vision generally is more comfortable and seems more natural.

Because of these advantages, progressive lenses have become the most popular multifocal lenses sold in the United States.

The right multifocal lenses for you

The right multifocal lenses for you will depend on your age, your visual needs, your budget and other factors. Visit us today for more information about bifocal, trifocal, and progressive lenses and to get a customized solution to your vision and eyewear needs.

Occupational bifocals and trifocals are specialized multifocal lenses created for specific jobs, hobbies or tasks. They are designed for people – generally over 40 – who have developed presbyopia, a condition in which the lens of the eye weakens and it becomes difficult to see objects that are close up. They differ from regular multifocal lenses in that the magnified power areas to see close and intermediate objects are typically larger and positioned in a different area on the lens, according to needs of the designated task.

Occupational bifocal and trifocal lenses are intended for specific tasks and not for everyday use. Here are a few examples:

Double-D Lenses

The most popular type of occupational lens is the Double-D lens. The lens is divided into three segments, with the top designed for intermediate vision, the bottom segment for near vision and the rest for distance. This design is ideal for people who need to see close both when looking down (to read something) and when looking overhead. Professionals that frequently use Double-D lenses are auto mechanics (who have to look overhead when under a car), librarians, clerks or office workers, (who have to look at shelves overhead) or electricians (that are often involved in close work on a ceiling). They are called Double-D lenses because the intermediate and near segments of the lens are shaped like the letter “D”.

E-D Trifocal Lenses

As opposed to Double-D lenses which have the majority of the lens for distance vision, E-D lenses focus on intermediate vision with an area for distance on the top and for near vision on the bottom. These are ideal for individuals who are working at about an arm’s-length away the majority of the time, such as on a multiple computer or television screens, but frequently need to look up into the distance or close to read something. The “E” in the name stands for “Executive Style” which represents the division between the top distance vision lens and the bottom intermediate vision lens which goes all the way across the lens. “D” in the name of the lens is due to the fact that the near section in the bottom of the lens is shaped like a “D”.

Office or Computer Glasses

Multifocal lenses designed for office work provides the largest section with an intermediate lens designated for viewing the computer screen and a smaller area for limited distance vision. You can have progressive or trifocal lenses that incorporate near vision as well.

Golf Bifocals

That’s right, there are even specialized lenses made for golfers! Golfers need to see a wide range of distances during their game from their scorecard, to their ball on the tee, to hole far away to line up their drive. In these lenses, the close segment is small and placed on an outer corner of one lens, to allow for brief close vision but not interfere with the distance game. Usually, right handed golfers will have the lens on the right side and vice versa.

Personalized Lenses

Standard multifocals can be redesigned to adapt to specific tasks or hobbies simply by changing the size, shape or location of the different segments. Many adults over 40 would benefit from having multiple pairs of multifocals to give optimal vision for different tasks or hobbies they enjoy. Note that occupational lenses are made specifically for the task they are designed for and should not be worn full-time, especially while driving.

Once we reach the age of 40, its common to start noticing the natural effects of our aging eyes, such as having to hold your phone at arm’s length to read text messages. Medically, this normal change in our vision is called presbyopia and refers to the weakening of the lens inside the eye which is responsible for sharp focus and clear near vision.

You may begin to notice presbyopia setting in when reading starts to become difficult and the words begin to lose focus. You might also experience eye strain or headaches when trying to read fine print. This is where reading glasses come in. Reading glasses are non-prescription eyeglasses that magnify text (or any object you are viewing) to allow your eye to focus better at a close distance.

Styles of Reading Glasses

Single vision (as opposed to bifocal or trifocal) reading glasses come in two lens styles – full and half. Full readers offer a uniform magnification (the entire lens is the same focus) and you need to remove them to see clearly at a distance. These are ideal for individuals that spend a lot of time reading and don’t often have to look up during that time. Half readers are also uniform magnification but offer smaller frames that allow you to look over the lens when you want to see further away rather than removing the frame from your face.

Bifocal reading glasses offer two zones of vision within one less. The upper part of the lens allows for distance vision, while the lower part is for reading. Bifocals have a visible line across the midline which divides the two zones. You simply look into the part of the lens that offers the vision you desire.

Custom Made Vs. Over the Counter Reading Glasses

Over the counter or ready made reading glasses may be cheaper and more convenient than custom made glasses but they don’t take into account your individual needs. If you have no previous prescription and a light presbyopia, they may sufficiently suit your needs however in many cases, they can cause eye strain, dizziness and headaches when they are not the right fit for your vision.

Having an eye exam and ordering custom made lenses can meet your exact visual needs in each eye to create a comfortable and optimal correction for your eyes. You can also select the style and shape of the glasses that look and feel the best for you.

Even though presbyopia is a common condition that eventually affects most people at some point after 40, any time you experience vision changes you should see an eye doctor for an exam. Even if you decide that you want to start with ready made reading glasses, you should get an eye exam to ensure that your eyes and vision are healthy. Many serious and vision-threatening eye diseases can be stopped and prevented with early detection, so routine check-ups, especially when there is a change in vision, are critical for optimal eye and vision health.

Dry Eye Disease is a common eye condition – studies show that nearly 20% of North Americans middle aged and older suffer from dry eye disease. The probability of you developing dry eye if you are a woman, and older than 50, increases. Hormonal changes that older women undergo make it much more likely that they will suffer from dry eye as they age, including symptoms such as blurry vision and irritation of the eyes, according to the American Academy of Ophthalmology.

What are the biological changes that happen during menopause which affect your eyes? The tear film in the eyes relies on certain chemical signals to remain stable, and these signals get disrupted during and after menopause. Some doctors believe that androgen, a hormone implicated in menopause, may be the culprit causing dry eye problems for menopausal women. Eyes may become inflamed, which leads to decreased tear production, and possibly dry eye disease. Add in a dry environment and many medications and the risk factors for menopausal women increases exponentially.

Treatments for Dry Eye in Menopausal Women

Estrogen hormone replacement therapy (HRT) is sometimes used to treat menopausal symptoms, as the female hormone estrogen is one of the hormones that decreases during and after menopause. However, studies have shown that this treatment does not relieve symptoms of dry eye.

Refractive Eye Surgery

Refractive eye surgery, such as LASIK and PRK, may not be advised if you are 40 or older, and have dry eye disease. These procedures can affect nerve function in your cornea (the clear surface of your eye), which could worsen your dry eye problem. If you want to have a consultation regarding LASIK or PRK, it’s important that your eye doctor know about your dry eye condition. In that case, your eye doctor will know to do the appropriate tests to make sure that there is enough moisture in your eyes for laser vision correction.

There are other health conditions that are associated with dry eye and aging. These conditions include thyroid autoimmune disease, and rheumatoid arthritis. If you suffer from dry eye, make sure your doctor screens you for these diseases.

Allergies may cause eye inflammation, and may be the cause of your dry eye. Prescription and over-the-counter eye drops might relieve your dry eye and allergy problem. Your eye doctor will advise you as to which eye drops would be best for you.

Sometimes commonly prescribed medications can worsen, or even cause, dry eyes. Some of these medications are antidepressants and diuretics, which are often prescribed if you have a heart condition. Make sure to talk about this with your doctor if you suspect that one of the medications you are taking may be causing your dry eye problems. Perhaps changing your medication will be as effective, and won’t cause dry eye disease.