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Taming My Bifocal- your bifocal is not your enemy! |
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Choose Your Poison You need to choose your poison. |
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You fight a line in a bifocal or distortion in a progressive addition lens (PAL). We recommend the bifocal line. |
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People commonly believe it is difficult to adapt to a bifocal, and it is true for some. Yet, why is it difficult? Usually another vision condition is the culprit. Two main conditions make adaption difficult. One is an eye turn and the other is eyestrain. So much energy is used for these conditions that there is little energy left to adapt to that line or distortion in your vision.
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Why a Bifocal, not a Progressive?
The PAL is marketed mainly for cosmetics. No one can see your bifocal line. Thus, no one can look at your glasses and tell if you hit your mid forties. |
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The PAL is a molded lens that starts with your distance vision prescription in the upper 10% of your glasses. Through varying curvatures it ends at your near prescription in the lower 10% of your glasses.
As you move your eyes down this narrow channel, the power progressively gets stronger-hence its name. Everywhere else is distorted. |
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The PAL is especially narrow for your middle distance like computer screens and price tags on shelves. It is so narrow we make a special measurement to see if one eye is closer to your nose. If missed, one eye would see in the channel while the other would look through distortion.
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Most progressives have a clear reading area of only 5 inches at the typical sixteen inch reading distance. Many people struggle to find the sweet spot for each point from distance to a reading distance. The above picture of a progressive shows the areas of distortion. The darkened areas to the side are someone’s else’s prescription as the lens progresses from your distance to near vision.
No, a PAL is really not your pal. |
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Why is the area outside the channel someone else’s prescription?
A prescriptive lens has a curvature. The steeper the curve, the stronger the prescription. The curvature of the PAL gradually increases steepness from the top to the bottom of the lens. Since the PAL is molded, like a jell-O mold, the section of the lens outside the channel must also be curved. Those curves do not match your prescription. If you’ve ever put on someone else’s glasses, you can see the distortion from that. |
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A lined bifocal does not do that. It is fused. The lens starts with your distance prescription. A section is carved out on the bottom and another lens with your near vision prescription is placed in the carved out section. Thus, every portion of the bifocal lens is your prescription.
Usually 50 to 60% of the top of your lined bifocal is entirely your distance prescription. The whole width of the lined bifocal segment is your near vision prescription. |
You have clear vision across the entire page rather than the five inches limited with a progressive. You immediately see clearly no matter where you look, even the sides. You don’t have to move your head when reading, required by a PAL. Accordingly, you do not slow reading down and interfere with vision processing which the progressive does. Head movement slows down vision processing.
A Bifocal Mimics Natural Vision
Our eyes change focus immediately when we look from distance to reading up close. They do not progressively change like a slide projector zooming in and out. It is immediate. You want immediate clarity, and hunting for a sweet spot in the PAL slows vision function down.
Yes, there is a line to contend. Yet, people who do not have an eye turn or eyestrain mentioned earlier, normally adapt within a few minutes if not within three days. Some adapt immediately.
A Bifocal Mimics Natural Vision
Our eyes change focus immediately when we look from distance to reading up close. They do not progressively change like a slide projector zooming in and out. It is immediate. You want immediate clarity, and hunting for a sweet spot in the PAL slows vision function down.
Yes, there is a line to contend. Yet, people who do not have an eye turn or eyestrain mentioned earlier, normally adapt within a few minutes if not within three days. Some adapt immediately.
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Why does a PAL interfere with vision processing and reading speed? Because of the very narrow channel, you have to move your head to read. When you move your head, vision processing skills shut down and auditory processing opens up. Thus your reading speed drops to a maximum of 250 words per minute-about as fast as you can talk. Imagine what giving a progressive to a student does to the student’s academics. Go to FAQ and read about God knew we were going to play baseball. |
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Special Bifocals
Desktop computer screens present a problem whether you have a bifocal or a PAL. You have to tip your head back to view the screen through the near vision section. We have special computer bifocals where the top is set for that slightly further distance of the computer screen and the reading segment is for regular close work. PAL's attempt to do the same but still have a narrow view for both the computer screen and reading. Some occupations like carpenters, auto mechanics, and electricians require bifocals positioned in unique positions. Would anyone prescribe and fit a metal frame for an electrician! If you have any of those jobs ask us how we can make your work more comfortable. |
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How do I adapt to my Bifocal?
3 steps 1. Lower your chin if the reading segment gets in your way at distance. If the car in your rear-view mirror looks fuzzy, simply lower your chin and lift your eyes to avoid the reading segment. |
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2. Rather than raise your chin, hold reading material near your waist when the distance section is in your way. You could raise your chin, but who wants to drown in the rain? As an example, always fold your newspaper and hold it in your lap or on the table so you can glance easily through the reading segment without raising your chin. If you held the paper at its full length with arms extended you have to raise your chin to see through the reading segment.
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3. Look over the top of the bifocal line when on stairs or stepping off curbs. If you look through the reading segment, not only will the stairs appear blurry, they will appear to be at a different distance.
You would then probably miss your step and even trip. |
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Note: The golf thing! Some golfers fear the line will get in the way of their swing and request golf glasses with the reading segment placed lower. We now may have found a golfing problem. One of the biggest problems in hitting a golf ball is raising your head as you swing. With the bifocal you have to keep your head down.
How do I adapt to My Progressive? There are no special steps like we described above for a bifocal. In addition to moving your head up and down and sideways, you have to learn to tolerate distortions and small areas of clear vision. |
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Yes, many patients desire the progressives and we provide them. Not only do we provide them, we make sure they are measured correctly for you to give minimal discomfort. Don’t worry if you find the progressive intolerable, we will supply a lined bifocal if you return your progressive within two months.
WARNING:
Whether you have a bifocal or a PAL be careful during the first few days of adaption (up to two weeks for a progressive). You could miss your step on stairs or pour coffee on the table rather than the cup, etc.
WARNING:
Whether you have a bifocal or a PAL be careful during the first few days of adaption (up to two weeks for a progressive). You could miss your step on stairs or pour coffee on the table rather than the cup, etc.
Let's Be Frank About on-line ordering
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So you thought about ordering on line. It’s sure cheaper... and that’s what it is, cheaper. How is it cheaper, not less expensive, but cheaper.
That’s simple. The services are reduced. In reality they are non-extant. |
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In our office you are paying for the service, not the materials so much. As an example, single vision plastic lenses in our office cost $70.00. The laboratory cost for those lenses when they buy in bulk is $1.00. It is the services the lab and our office do to those $1.00 lenses that you pay. Thus, when the on-line company provides no services they can and do mark their prices down.
We provide 22 services for every pair of glasses. See below for each of those services. The on-line company only supplies one, and that is not done very well. |
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But wonder if I send your prescription with the measurement between my eyes into the on-line company?
Yes, you could and is required by law (often ignored by on-line companies). That only covers the first three of 22 points. That’s hardly any service at all. The on-line company has to make the prescription correctly which is highly doubtful. Recently we provided a patient with that measurement, and the on-line company made the glasses wrong causing double vision. |
Wonder if I send the name and measurements of my current frame into the lab?
Most on-line labs use their own frames (they can’t afford to offer quality frames at their prices). Even if you use the measurements of your frame, the same measurements in another frame do not mean that frame will match your face.
Most on-line labs use their own frames (they can’t afford to offer quality frames at their prices). Even if you use the measurements of your frame, the same measurements in another frame do not mean that frame will match your face.
Couldn’t you verify the glasses and customize them to my face?
Yes, you would pay a modest for the service that would last the life of your prescription. Yet:
1. We could not be sure we could bend the frame.
2. We could not be sure the frame would hold it’s adjustment.
3. The frame could break with an appropriate adjustment.
4. The frame may not even correctly fit your face.
5. The above four assume the prescription was made correctly. That is not likely.
If the on-line company made my glasses wrong, couldn’t I tell the difference?
No, you may not be able to tell, especially of the small discrepancies that cause your vision to change and worsen. The big difference you would obviously note and not even attempt to wear the glasses. Besides, we see very few people bring in on-line glasses for verification. Most that were brought in were wrong.
Yes, you would pay a modest for the service that would last the life of your prescription. Yet:
1. We could not be sure we could bend the frame.
2. We could not be sure the frame would hold it’s adjustment.
3. The frame could break with an appropriate adjustment.
4. The frame may not even correctly fit your face.
5. The above four assume the prescription was made correctly. That is not likely.
If the on-line company made my glasses wrong, couldn’t I tell the difference?
No, you may not be able to tell, especially of the small discrepancies that cause your vision to change and worsen. The big difference you would obviously note and not even attempt to wear the glasses. Besides, we see very few people bring in on-line glasses for verification. Most that were brought in were wrong.
The 22 points provided for every pair of glasses in our office:
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1. A comprehensive vision exam to leave no stone un-turned.
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2. The knowledge and expertise of the doctor to come up with the correct prescription for you.
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Dr henshaw does not just rely on what’s just left in the automatic refractor or in the phoropter (Vision tester) to determine your prescription. This includes your history, other vision conditions, and occupational and recreational needs.
3. The physical measurement of the distance between your eyes, especially if you
select an invisible bifocal (progressive).
4. The type of lens best for your needs
especially computer use
sports
industrial
drafting
night watchman (anti reflection that fogs when going from a hot to cold environment may not be a good idea)
dry cleaner worker
5. The height of the top of your bifocal whether visible or invisible
6. The material of the lenses
plastic
glass
polycarbonate
trivex
high index
specialty lenses like double bifocals
7. The safety of the lens worn less than an inch before your eyes
8. The guarantee of the lenses
9. The add-ons' to your glasses:
tints,
Anti-reflection coating (ARC). The VSP plan has over 12 different types of ARC.
edging,
base curve
10. Your facial features that may require certain frames.
High cheek bones
flat nose
narrow nose
large nose
bent nose
large head
small head
round head
11. Styling of your glasses
12. Selecting the sizes of your glasses before ordering:
eye size
eye shape
temple length
bridge style
nose piece type
strength of the frame (we have sent some weak frames back to our vendors)
3. The physical measurement of the distance between your eyes, especially if you
select an invisible bifocal (progressive).
4. The type of lens best for your needs
especially computer use
sports
industrial
drafting
night watchman (anti reflection that fogs when going from a hot to cold environment may not be a good idea)
dry cleaner worker
5. The height of the top of your bifocal whether visible or invisible
6. The material of the lenses
plastic
glass
polycarbonate
trivex
high index
specialty lenses like double bifocals
7. The safety of the lens worn less than an inch before your eyes
8. The guarantee of the lenses
9. The add-ons' to your glasses:
tints,
Anti-reflection coating (ARC). The VSP plan has over 12 different types of ARC.
edging,
base curve
10. Your facial features that may require certain frames.
High cheek bones
flat nose
narrow nose
large nose
bent nose
large head
small head
round head
11. Styling of your glasses
12. Selecting the sizes of your glasses before ordering:
eye size
eye shape
temple length
bridge style
nose piece type
strength of the frame (we have sent some weak frames back to our vendors)
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Adjust-ability of the frame.
It needs to be flexible to bend but not too loose so as not to hold its shape. We have sent some nonadjustable frames back to our vendors |
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13. Correctness of the written prescription by the time it gets to a lab (Our lab is set to pick unusual trends in the Rx to guard for error, and does not rely on the quality (or lack thereof) of a fax.
14. The quality of the equipment at the laboratory and of the lenses supplied by the lab. Our lab is over a 10 million dollar facility. 15. The training and expertise of the technicians (or lack of) at the laboratory 16. The adherence to standards of manufacturing the glasses at the lab |
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17. The verification by the laboratory before sending the glasses out (our lab has over a 95% correct rate).
18. It is not turn around time but quality. Just because it is delivered quickly doesn’t mean it is right. Although our lab delivers in a week and in emergency we can rush in 3 days.
19. Once the lab makes the glasses we verify them to be sure they are made correctly before we deliver them to you.
20. We then customize the glasses to your face for ideal optical use and comfort.
Glasses touch at only three points:
1. on the nose
2. in the mastoid hollow behind the right ear
3. in the mastoid hollow behind the left ear
18. It is not turn around time but quality. Just because it is delivered quickly doesn’t mean it is right. Although our lab delivers in a week and in emergency we can rush in 3 days.
19. Once the lab makes the glasses we verify them to be sure they are made correctly before we deliver them to you.
20. We then customize the glasses to your face for ideal optical use and comfort.
Glasses touch at only three points:
1. on the nose
2. in the mastoid hollow behind the right ear
3. in the mastoid hollow behind the left ear
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The temples do not touch the ears. That hurts.
The temples do not touch the side of the head. That makes them slide down your nose. The glasses need a pantoscopic tilt (tipped so the bottom of the lens is closer to your face than the top) or your field of view is narrower and you can have distortion. The front of the frame needs to be level on your face. This is especially important in a bifocal. |
21. During use your glasses are often bumped and we realign them.
22. You have a personal relationship with us whether things go well or there is a problem. You are heard. Online can’t offer that.
22. You have a personal relationship with us whether things go well or there is a problem. You are heard. Online can’t offer that.
WARNING???? Prop 65 Now Affects Your Eyes!!!
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All of California's eye docs are now subject to Prop 65 too! Just like stores that sell any plastic products. Proposition 65 requires that CA businesses must go to an added expense and inform you of some 900 products that a CA agency deems carcinogenic.
The Office of Environmental Health Hazard Assessment (OEHHA), deems the product may cause cancer, birth defects or reproductive harm. |
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Prop 65 Now Affects Your Eye Doc
From Cindy P. Wang, OD, FAAO President, San Gabriel Valley Optometric Society an un cut notice from the California Optometric Association: Alas, your optometrist’s office is now subject to Prop 65 too, just like all stores that sell any plastic products. Proposition 65 requires that Californians be informed of consumer products that may cause cancer, birth defects or reproductive harm. |
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Recently, a chemical known as bisphenol A, BpA, was added to this list. BpA as many of you know, is found almost everywhere – food containers, compact discs and DVDs, bicycle helmets and electronic equipment. At your optometrist’s office, it’s found in trace amounts in some plastic eyeglass frames and in polycarbonate,lenses, a very common lens used in eyeglasses. With only trace amounts of BpA detected in a polycarbonate lens and plastic eyewear frame, How much exposure are you really getting? The studies have shown that most exposure to BpA is largely ingested and that any exposure through skin contact is negligible.
What does this mean for us spectacle lovers? First of all, polycarbonate lenses are placed inside your frame and has virtually no contact to your face (unless you bought a pair of rimless frames that sit directly on your cheeks.) [Editor's note: our office knows how to help you select a rimless frame that does not touch your cheeks and further can adjust them to avoid the contact. If any frame you may desire could not avoid cheekbone touch, we would warn you.] Secondly, polycarbonate lenses and plastic frames have been widely used for decades, with no direct correlation to an increase in health problems. Lastly, there is not enough research to indicate how much exposure you are truly getting from skin contact. If you’re in the habit of chewing on your plastic frames or licking your lenses, then obviously, you’d want to stop that, if not for the fact that that’s a weird and unhygienic habit.
So, what should you do? Most of the eye care industry is not flummoxed by this recent change in consumer warning. But if you are concerned, there are plenty of other optically superior, thinner and more lightweight lenses available on the market. And instead of plastic frames, choose a titanium or plant based (wood or bamboo) frame instead. Ask your optometrist, there are plenty of other options available on the market. And lastly, buy reputable frames and lenses with known quality, whose manufacturer you can directly contact if you have specific questions regarding manufacturing and ingredients.
For further reading, please visit the links below.
http://oehha.ca.gov/proposition-65 https://www.thevisioncouncil.org/members/california-prop-65
What does this mean for us spectacle lovers? First of all, polycarbonate lenses are placed inside your frame and has virtually no contact to your face (unless you bought a pair of rimless frames that sit directly on your cheeks.) [Editor's note: our office knows how to help you select a rimless frame that does not touch your cheeks and further can adjust them to avoid the contact. If any frame you may desire could not avoid cheekbone touch, we would warn you.] Secondly, polycarbonate lenses and plastic frames have been widely used for decades, with no direct correlation to an increase in health problems. Lastly, there is not enough research to indicate how much exposure you are truly getting from skin contact. If you’re in the habit of chewing on your plastic frames or licking your lenses, then obviously, you’d want to stop that, if not for the fact that that’s a weird and unhygienic habit.
So, what should you do? Most of the eye care industry is not flummoxed by this recent change in consumer warning. But if you are concerned, there are plenty of other optically superior, thinner and more lightweight lenses available on the market. And instead of plastic frames, choose a titanium or plant based (wood or bamboo) frame instead. Ask your optometrist, there are plenty of other options available on the market. And lastly, buy reputable frames and lenses with known quality, whose manufacturer you can directly contact if you have specific questions regarding manufacturing and ingredients.
For further reading, please visit the links below.
http://oehha.ca.gov/proposition-65 https://www.thevisioncouncil.org/members/california-prop-65
You have probably seen signs in stores and on products indicating that some items “contain a chemical known in California to cause cancer.” More than 900 substances belong on this list of carcinogenic products.
Photo:Courtesy of Robert Meeks on Flickr
Photo:Courtesy of Robert Meeks on Flickr
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Recently bisphenol A, (BpA), was added. Some products that contain the dastardly BpA include food containers, compact discs and DVDs, bicycle helmets, and electronic equipment. Yup, traces are in some plastic frames and all polycarbonate lenses. How much exposure are you really getting? Studies show most exposure is from ingestion while skin contact is negligible.
All, polycarbonate lenses are inside your frame with no contact to your face unless your rimless frames touch your cheeks. Yet, our office selects rimless frames without cheek touch. |
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Secondly, polycarbonate lenses and plastic frames have been widely used for decades, with no direct correlation to increased health problems.
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Lastly, there is not enough research about skin exposure. If you chew on your plastic frames or lick your lenses, you’d want to stop that, if not for the fact that it’s a weird and unhygienic habit.
So, what should you do? If you’re concerned, plenty of optically superior, thinner, more lightweight lenses exist. Also, plastic frames have options. Before you give up your plastic frames and polycarbonate lenses, note that one of our patients who is a chemical engineer says there is no harm at all. |
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PS:
In other words the State of CA doesn't want you to eat your plastic frames or polycarbonate lenses!, and we have to tell you not to do that.! |
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Eye Glasses Guide
EyeGlass Guide will help you better understand the many lens choices available to you. This on-line tool will guide you through a series of questions about you, your lifestyle and your specific eyewear needs. At the end, you'll receive eyewear suggestions specifically tailored to meet your needs. EyeGlass Guide is brought to you by Transitions.
Please note this site overemphasizes the use of ultraviolet blocking lenses of which Dr, Henshaw differs. There is no valid research that proves ultra violet light causes cataracts according to the chief of research at the industry that manufactures photo sensitive lenses.
Please note this site overemphasizes the use of ultraviolet blocking lenses of which Dr, Henshaw differs. There is no valid research that proves ultra violet light causes cataracts according to the chief of research at the industry that manufactures photo sensitive lenses.
Photochromic Demonstrations
View an instant demonstration of Transitions photochromic technology. See how lenses darken and fade back to clear to provide continual visual comfort and protection. Demonstrations brought to you by Transitions.