Breen wrote:
I am a myopic mid-50s adult with extremely good peripheral vision.  As a result, I am very sensitive to distortion of any form (the barrel effect), and am aware at all times of the edges of my glasses, even though they are attached to the bridge and temples only. I also have a second pair of single vision glasses with a field of focus optimized for computer use. Progressive lenses are out of the question.

My previous single vision glasses were Nikon high refractive index lenses (Nikon 5, with RI 1.74), and I was very happy with the level of distortion, which while always present, was tolerable.

My new prescription (OD/OS -3.25 spherical only, 0 cyl.) resulted in an opportunity for me to try out the Nikon SeeMax lenses, which promise minimal distortion.  However, the result is exactly opposite from what I expected, and exhibit far more curvature distortion than my old lenses.  My previous prescription was OS/OD -2.25 spherical, which is a significant difference.  However, when I look at the details on the new glasses receipt, I see they used the 1.6, and not the higher 1.74 (or even 1.67) refractive index lenses. This was a surprise to me, as I assumed that they would order the same RI as the old ones, and I will be getting them to replace them with the thinner 1.74 lenses to minimize the visibility of the edges of the lenses (due to extremely good peripheral vision).

Could I expect less curvature distortion with the higher refractive index of 1.74, vs. the 1.6 that I’m unhappy with?

What if anything, does the base curve have to do with distortion, and how is this related to the refractive index for the lenses in question?

Also, are there other lenses which might be more suitable for me than the Nikon SeeMax to minimize peripheral distortion?

ANSWER

Dear Breen
From your letter it appears that you are a very “sensitive observer” – someone who notices distortions that the average person would not detect. The barrel effect that you mention tends to be more noticeable with an increase in the size of the lens that you are looking through. If there is more peripheral lens to look through, you will be exposed to more peripheral distortion. Although you did not mention lens size in your letter, if your new lenses are larger than your old pair, it may be a factor in the distortion you are experiencing.
Typically, as the index of the lens increases, there is an increase in the amount of radial astigmatism (another form of distortion) in the lenses. However, the customized lens surfacing techniques such as those used with the Nikon SeeMax have typically made great improvements in reducing the level of the other lens distortions (such as barrel distortion) experienced by the wearer. However, a -3.25 lens will induce more barrel astigmatism than an equivalent sized -2.25 lens made of the same material. A 1.74 index lens at -2.25D would be flatter and thinner than a 1.6 index lens at -3.25D and this difference, in your case, may also be contributing to the distortion you are noticing.
The Nikon SeeMax is a well designed lens with a good track record. There are other lens options from different manufacturers that also perform well. Unfortunately, there is very little reliable independent data available that compares lens performance from different manufacturers. Most of the information available is self-generated by the lens manufacturers, and to no one’s surprise, each manufacturer appears to claim that their own lens performs best. Hard data aside, the other factor that the lens manufacturers cannot control is the visual perception of the patient wearing the lenses. It has been my experience that patients with same the very similar lens prescription, visual demands and frame size still express different preferences in their lens design choices. Based on your apparent sensitivity to distortion, it may be advisable to stick with a frame and lens design that you have successfully worn in the past.
Boring, but it sometimes does the trick when all else fails!
Dr. Smit

Mike wrote:
Hi,

I recently had my prescription updated and went to get a new pair of glasses but ran into some visual distortion issues.

My normal optometrist (that I have been seeing since I was 10, I am 27 now) was not available at the time, so I made use of the in-house one where I was getting my glasses.

The prescription [I don't have it] (which was later checked by my normal optometrist) was accurate, save for the prism. For whatever reason, She could not see it while taking the measurements. So she added the prism from my glasses that I was wearing at the time (a 1 B0 prism).

The optician did the glasses. When I tried them I noticed a significant distortion of the ground immediately in front of me, it was like I was walking up a 3′ hill all the time. This was looking ahead normally while walking. It was also like they were magnifying the image as well, as if I looked straight down, my body/legs appeared to be about 2′ tall (I’m 6′). I made a point of wearing them for a few days to see if it was an adaptation issue but there was not noticeable improvement.

At that point I went back to the opticians and they rechecked everything PD, prescription, as well as positioning of the frames on my face to no avail. They suggested that I go to my normal optometrist to double check the prescription. Which I did and ended up with:

OD -800 -075 175 1.5 B0
OS -650 -050 008 1.5 B0

I took this back to the opticians and they re-did the lenses with the new prism. These were a no go as well. Same visual distortion. Again, they checked the lenses, position etc. All seemed ok. Though they noted that the base curve of the new lenses was not the same as my old ones. So they suggested that they re-grind the lenses with the old base curve to see if that would fix the situation.

While it did improve the distortion it was no longer a 3′ hill immediately in front of me, there was still a significant rise in the ground probably from 6 to 10′ away, I would have to guess that it looked like it was about 1′-2′ rise, though it was smooth not abrupt, kinda like a pronounced crown in the road.

At that point I had given up on the glasses as the opticians could not provide any answers or other things to try, other then to check the prescription with my optometrist again. Which I did and ended up with the most recent prescription of:

OD -775 -075 175 1.5 B0
OS -675 -050 006 1.5 B0

I have not had this made into a set of glasses yet, as I don’t know what was causing the problem and I am a little leery of going through this again considering the cost of the lenses alone usually runs about $300+.

The lenses they were using above were Zeiss 1.67 RI, their lab was using Essilor Kappa. The frame size was 49-19, Oakley Rotor S.

My old glasses (which I am still wearing) were from Lensecrafters, the lenses are Featherweights (polycarb 1.54 RI?). Frame size 46-18, similar lens shape to the Oakleys, rounded rectangle. Old glasses prescription is:

OD -750 -050 180 1.0 B0
OS -625 -050 180 1.0 B0

Any ideas what was happening?

Thanks for your time.

ANSWER

Mike
Dear Mike
I will do my best to offer some suggestions based on the information that you have given me. For starters, yours is a fairly high prescription, and high prescriptions create more distortions than lenses made in a lower prescription. Secondly, I suspect that you are a sensitive observer and that you may be bothered by induced distortions that might otherwise go unnoticed by the average observer.
It appears that your new prescription is a little bit stronger, that you are wearing a slightly larger frame, that the amount of “base in” prism has increased slightly and that the axis of the astigmatism has changed slightly (going from exactly horizontal to being tipped up slightly at the outside of the frame). Each of these changes, by themselves, would probably not cause a great change in visual perception. However, these four small changes, in combination, may be enough for a sensitive observer to notice. In addition, it is possible that the “wrap” of the new frame is different that the vertical centration of the lenses may be different from what you are used to wearing. These factors could make your adaption to the new glasses a little more difficult.
Fortunately, most patients do eventually adapt to changes in prescription and lens design. If you have worn the glasses for a period of a few weeks and do not experience any improvement in your symptoms, you may want to try to go back to a smaller frame. As a last resort, you may also want to go back to the polycarbonate lenses, but any improvement in spatial perception you might gain may also be offset by the generally lower optical quality that polycarbonate lenses provide away from their optical centers.
I wish you luck. It sounds that you and your different care providers are doing their best to make things work for you. Hopefully with a little more perseverance you will be successful.
Best of luck
Dr. Smit

Robyn wrote:
I have been wearing a single contact lens in one eye for all of my adult life (I am thirty years old) and wore glasses throughout my childhood.

I recently had my eyes re-examined, and obtained a new contact lens prescription. At the same time I inquired about glasses as an option as I travel frequently and wanted to see if there was an alternative to dry eyes on long flights. My optometrist suggested that I wait to see how my eyes adapted to the new contact lens, but otherwise that it wouldn’t be a problem if I were to get glasses as an alternative.

Fast-forward to a few months later when I ordered new glasses from his office. One lens is near perfect and the other has quite a strong prescription, as expected. They arrived, and despite my best efforts to adjust to them over a two week period, they do nothing but make me nauseous and motion sick.

I’ve returned to my optometrist for suggestions, indicating that the glasses make my vision strange and give me motion sickness while wearing them, and his response was that glasses will always do this for me - I should just stick with contact lenses.

While that may be true, I’m extremely disappointed (and surprised!) that this recommendation did not come out until after I had purchased glasses based on his assurance that they would be fine as long as my eye adjusted well to my new prescription.

The office will not refund the full cost of the glasses - and are not offering other solutions, either, aside from keeping these costly glasses that are virtually unusable.

Are there rules that govern the dispensation of glasses and vision products (I live in Ontario) - and whether or not customers/patients must be satisfied with the end-product? I have generally been very happy with my optometrist and his expertise, but I can’t help but feel let down by this experience.

ANSWER

Hello Robyn,
I’m sorry to hear that you find yourself in this situation.
Not knowing your exact prescription and visual acuity, it is very difficult for me to make any other suggestions for adapting the glasses.
On the few instances that I have had a patient who is unable to adapt to a prescription (and there is nothing wrong with the glasses themselves), I have offered a refund.  This is not a standard practice, however, and there are no definite rules.  The only thing I can suggest is to return to your optometrist and again voice your concern and ask again for a refund if you feel it’s warranted.

Good luck,
Dr. Donati

Beth Ann wrote:
I have just started wearing glasses for the first time. I got two pairs, one for computer I work on a computer 12 hr shifts 4 days on and 4 off. The other are progressive, long story short I am having a difficult time getting use to both and have been back to the optometrist and some adjustments made and asked to try them for a few more days, if this doesn’t work, she is advising digital lens.  I am totally confused as this is my first time ever wearing glasses…  Please help.

ANSWER

Beth Ann,

First time glasses do take some getting used to.  For the computer glasses, you might help your Optometrist by having someone help you measure the distance from your eyes to the computer screen when you are sitting in your “normal” work position.  This will assure that the computer glasses are appropriate.  Progressive lenses can often take a couple of weeks of constant wear to be totally comfortable.   The digital lenses are the newest type of progressive lenses, and may be the answer for you if all else fails.

Dr. Joan Hansen - Optometrist, for CAO

Cristian wrote:
Hi,

Please help me to understand what is going on with me and my new glasses.

History - In the last +30 years I have worn only Zeiss Single Vision glass lens, in the last 5 years being -5.75 Sph (glass). I have always been extremely happy with my glasses, although 5 years ago I tried non Zeiss lens and I returned them due to chromatic aberrations (yellow/blue edges around bright white contrasting surfaces), as well as poor peripheral lens focus. With the Zeiss I have now I do not experience any of these, and I can look all the way through the side edges of the lens and the image remains sharp, with no colour aberrations or shape deformations. BTW – the thickness at these lens edge is ~4 mm.

Now - my new Rx calls now for -6.25 Sph -0.25 Cyl with Add +1.5 Axis 80.
Given my experiences in the past, my optician told me to go with Nikon Seemax, since they will give me the widest field of vision, and virtually no aberrations – which I did. The result: I am at the second pair now (looks like first one was not positioned correctly) – and my distance field of vision is terrible, no matter the adjustments they tried: basically, if I look forward (far) I see perfect in the lens’ centre, and just few degrees off centre, left or right – it becomes blurry, like for e.g. road signs on the left or right side of the street, at ~50m ahead – I must turn my head, or cannot see them in focus anymore.
I understand that PAL will not offer a wide distance field of vision anywhere near compared to my Zeiss – but I found the results terrible (I am talking about few millimetres left or right on the far field of the lens, not the edge of it, and all while using Seemax…). In addition, I really don’t understand how come latest technology will produce lenses not much different in Rx, but much thicker at same diameter (now at ~7 mm compared to 4 mm) – but this is secondary, the lack of distance field of vision is what I just cannot adapt to.
My optician tells me “it’s me, and I need to adapt” (to something bad, I might ask?)

Please comment or recommend a course of action.

Thank you.

ANSWER

Hi Cristian,

It is true that glass lenses will give minimal aberrations.  This will give you good peripheral vision.  Plastic high-index lenses have become a lot better over the past few years.  Aspheric high-index lenses give much less distortion in the periphery of the lens and you can now get ‘free-form’ single vision lenses that are bi-aspheric, which would give the clearest peripheral vision.  I will also tell you that I do not recommend glass lenses because they are unsafe.  They will shatter much more easily and if they do shatter the pieces can be very sharp and can cause severe eye injuries.  Also glass is extremely heavy.  I do not sell any glass lenses in my practice.

Moving on to your progressive lenses, you are exactly right that with progressive lenses the clearest  vision is in the centre of the lens.  To see clearly you must be looking through the centre of the lens.  When you look an object you need to point with your nose to have that object come into clear focus.  This is something that people do adapt to.  As a result progressive lens wearers do have to move their head more than people who wear single vision lenses. Sometimes adaptation to this can take a long time.  Every person is different, but I would say it can take at least 2-4 weeks to adjust and sometimes longer.  The Nikon SeeMax is an excellent lens.  If you find you cannot adjust or do not want to deal with this limitation you could go back to single vision lenses or go to a straight top bifocal (there would be a line on the lens).  The advantage of the bifocal is that you would have better peripheral vision; the disadvantage is that they are not good if you do any amount of computer work.  If you do a lot of computer work you would be better off going with two pairs of glasses – one for distance tasks and one for near tasks.

As far as the thickness of the lens is concerned that depends on a number of factors.  The first is the index of the lens.  The higher the index the thinner the lens will be.  Glass lenses have an index of about 1.52.  Regular plastic lenses have an index of 1.5.  High index plastic comes in 1.6, 1.67 and 1.74. With your prescription I would recommend a high index lens.  The size and shape of the frame and where your pupil is located in the frame also play a role.  Square frames will have thicker edges than an oval frame and if your pupil is not centred in the frame, one edge will be thicker.

Dr. Carol Doman

Amira wrote:
Hi. It’s been 4 years since I’ve had an eye exam. Recently I got one and my RX was -5.25. My contacts prior to this were -3.25. I purchased my glasses with the new RX and it’s been 2 weeks since I’ve been wearing them but they sometimes make me feel off balance and they appear TOO clear and my eyes feel a bit of strain. Does this mean my RX is too high or should I give myself more time to adjust to wearing the glasses?

ANSWER

Dear Amira:
It is certainly possible for your eyes to change as much as you have noted over a period of four years, especially if you are under twenty years of age. Such a large change in prescription often creates difficulty in adaptation for a few weeks. If after four weeks your symptoms are not showing signs of improvement, I would bring your concerns to the attention of your optometrist.
Best regards,
Dr. Henry Smit

Sharon wrote:
I started wearing Varilux progressive lenses 3 days ago.  My prescription is Left Eye 7.5 and Right Eye 6 with the presbyopia part of 2.5.

My distance vision with the new glasses is great.  The near vision is fine too - although the window of clear vision is so small it feels like I am reading through a straw.  The intermediate vision is brutal.  I can’t see anything clearly unless I tilt my head way back and look out of the bottom of the glasses.  For example, at a restaurant I can clearly read the menu, see the food on my plate and look around the restaurant.  My husband sitting across from me is totally blurry.  In the bathroom, I can’t see myself clearly in the mirror.  At work I can’t see any of the stuff I have posted around my desk (I am a bookkeeper) and viewing the computer is really problematic.  I can’t imagine having to go through the rest of my life tilting my head back just to be able to see at the intermediate level.  The optician said it takes 3-5 days to adjust but so far the intermediate vision is exactly the same as it was when I first put the glasses on.  Could there be a problem with the lenses?

ANSWER

Dear Sharon

Is this your first time trying progressive lenses?  It can take some time to adjust to the way the lenses work.  The distance vision is at the top of the lens, intermediate near the middle and the reading area towards the bottom of the lens.  If you look to the side, the vision will be blurred so you must turn your head for the correct position.  Initially, you will do this with thought but afterwards it will become second nature.  The reason the vision is blurred at the sides is due to the change in the power of the lens.   The natural eye is wonderful, progressive lenses are man’s way of correcting the effects of time and it is the best option we have at the moment.  The spectacles may need a simple adjustment- as I explained if the spectacles are not sitting properly you might be looking through the wrong part of the lens.  There are a few options for people who need a large intermediate area (bookkeepers) to work on the computer.  Also, the way your work station is set up might affect your ability to work with the new progressive lenses.  Measure the distance from your computer screen to yourself.  Is it on a stand or off to the side?  It is best to go back to the dispensing optician and explain the problems you are having so that they can help you.  Your problems might be solved with minor adjustments to the frame.

Alan wrote:
I have a new prescription for my glasses. The new prescription is not as strong in my bad eye as it was previously (+5 instead of +5.5) but the axis has been changed a bit.

The new lenses have been in for a week now and I think I am slowly getting used to them but I am finding that my eyes (both the bad eye and the good one) are tiring easily and losing focus for a short time. This is usually when I have been reading for five or ten mins.

Is this expected while adapting to a new prescription? Is it just the eye muscles getting used to being used in a slightly different way?

ANSWER

Dear Alan

You have a hyperopic prescription meaning that your eyes have to adjust all the time to see clearly, at far and mostly at near. I don’t know your age but it is quite rare that hyperopes at your level “improves” at a given time. Usually, hyperopia is structured after 15-20 years old and does not vary until 40-45 years old when it progresses.

The best way to find your real prescription and accordingly to alleviate the “stress and fatigue” symptoms you have is to ask your optometrist to make an eye examination under cycloplegia. At this time, optometrist uses a diagnostic drug (a cycloplegic) that alter the capacity of the cristalline lens, inside of the eye, to adjust for hyperopia. This is why the optometrist can mesure the “real” power of your eye. Habitually, the prescription of your glasses have to match with this results to alleviate any fatigue or effort to focus, especially at near.

If the prescription is confirmed and right (at +5) the problem could be in the centration of the glasses in your frame. At this level of prescription, we have to be very cautious in the choice of the material, the type and shape of the frame that is selected and to make the appropriate mesurements in height and width to center the lenses according to your pupils.

In summary, I would first check the accuracy of the prescription by a cycloplegic exam of the eyes and to revist the fitting and centration of the lenses if the prescription is confirmed as valid.

Good luck,
Dr. Langis Michaud, Associate Professor,  U de Montréal

Ricardo wrote:
I recently got my first pair of progressive lenses, but after six weeks they still drive me crazy. I feel that there is a top region for distance, a middle region that is basically useless, and a lower region that is slightly more focused than my unaided eyes, but with severe distortion. If my head is slightly tilted, everything is distorted. Also, I can never find the right zone to focus on my computer screen. If I were to get progressives that went to zero magnification at the bottom, would the problem be reduced? In other words, would the transition between zones be gentler, or not?

ANSWER

Hello Ricardo,
The short answer is “no”.  If you are noticing little difference between your reading zone and your unaided vision, then you will most likely not find any improvement with what you suggest.  It is possible, however, that some of the difficulty you are having with your new lenses may be due to misplaced optical centers (meaning that you may just need to have the glasses adjusted so that the center of the lenses is sitting where it’s supposed to).  If this is not enough to ease your symptoms, you may want to talk to your optometrist about the possibility of getting a prescription that is designed to be used specifically at the computer.  Also keep in mind that it will take longer to adapt to your new progressives if they are not worn consistently.
Hope this gives you a place to start,
Dr. Donati

George wrote:
Hi. I’m 26. I have strong astigmatism in one eye and a lot of near-sightedness but little astigmatism in the other. One optometrist has told me, jokingly, that it seems as though my eyes are from two different people. Uncorrected, my left eye is about 20/50, my right eye about 20/100. Supposedly the difference comes from retinal scarring when I was young, but I’ve never been diagnosed with amblyopia.

Here’s my problem: I recently got a pair of glasses from my ophthalmologist that drive me nuts. There’s a feeling of constant tenseness, and I have a hard time maintaining an awareness of things with my peripheral vision, and when I go into busy interior areas, such as a grocery store, I become very confused. My concentration suffers, for instance, and I jarringly lose track of thoughts whenever I shift my eyes to refocus. Reading is also difficult. I told all of these things to the doctor when I went in for a recheck. He said I would get used to the new prescription, and I have not.

I noticed that that the image I’m getting on the left side is squat (from the astigmatism correction) and the right eye is tall and skinny and distorts heavily toward the left and right edges. When I insisted on the difficulty with this prescription, suggesting that the squatness on the left could be causing my discomfort, my ophthalmologist said that he had indeed added an additional dioptre of astigmatism correction, and he could remove it if I wanted, at the cost of sharpness.

There are three things keeping me from having confidence in that solution: 1) It originally came from ME and not from my doctor, who other than shine a light in my eyes performed no tests for binocularity or refractive difference, so I suspect that he’s not properly examining my eyes, merely relying on my last prescription. 2) For about the 8 months leading up to my current prescription, I did not use glasses at all. I performed a lot of high-stress public-speaking related tasks and got very used to squinting and functioning without glasses. 3) I have a very old prescription, from a different doctor, that causes none of the symptoms I described above and is much, much easier to read with.

My question is this: I have no insurance so visits can be expensive. I see a few courses of action: 1) return to my ophthalmologist and request a comprehensive eye exam, telling him about the old prescription and reiterating that I went without glasses for 8 months. 2) Get a comprehensive eye exam from somebody else, and if so, would it be better to go to an optometrist, an ophthalmologist, or an orthoptist?

Before I do anything at all, I’d also like to know what an optometrist thinks might be going on.

Thanks so much!

ANSWER

You mention not using your glasses for 8 months, and I hope this means that you do not drive. Changes in Astigmatism correction can cause the distortion that you are describing. I would suggest a new exam, and I would suggest that you see an Optometrist as these doctors are trained very thoroughly in the determination of the best possible and most comfortable lenses for your glasses.  Explain the problem to the new Optometrist and bring along all of your glasses.

Dr. Joan Hansen - Optometrist, CAO