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

Adam wrote:
I have a student who is not able to read the board from the centre of the room.  I asked if he had been prescribed glasses, and he said yes, but that his parents told him he couldn’t wear them on a regular basis and so he had to sit in the front.  His parents told me that they didn’t want their son wearing the glasses regularly in class because their natualpathic optometrist told them that his vision would get worse if he wore them and better if he didn’t wear them.

My understanding is that this is a myth based on a change in perception, but I’ve also heard of other people being told this by their optometrists.  Is there any credible evidence for this stance?

Thank you.

ANSWER

Adam,

Thank you for your question.  First, it is difficult to answer since we don’t know all the real facts, but perhaps you could share some of this information with the family in question.  I also must say I have never heard of a natualpathic optometrist.

You are correct about the myth. Not wearing his glasses will not slow progression of myopia (near sightedness). There is no natural way to alleviate the development of myopia.

If choices have to be made, since school is important to a child’s development, I would suggest that this child choose the classroom to wear his glasses. He could easily take them off to walk to and from school, while playing outside, while doing sports, and while at home. Squinting and struggling to see often results in headaches and may hinder his education.

Children grow until they are in their mid 20s and during this growth phase, the eyeball will grow and cause myopia to increase. We have not found a way to stop this growth as yet. Many studies have been done on ways to reduce myopia, and you can read about them on this website: www.allaboutvision.com/parents/myopia.htm

Ian wrote:
I am 74 years old and need glasses for reading. My present glasses as prescribed by the optician are a magnification of 4. These are not very effective unless the print is a very bold black on white. What is the limit of magnification available for reading glasses?

ANSWER

Dear Ian,
It is very difficult to answer to your question without knowing your ocular and visual condition. Near vision should be addressed after a proper evaluation of your distance vision and of your ocular health, to make sure that there is no pathology involved, such as cataracts, glaucoma or macular degeneration. These diseases can limit the level of visual acuity and no glasses can help to restore it.
My best advice would be to consult an optometrist, not an optician, and to have a thorough ocular and visual examination. Your optometrist will determine the cause of your visual deficiency and will prescribe, if possible, the best power to you. You have only 2 eyes, working together as a team. It is unwise to play with them by juggling with the powers without knowing the underlying ocular conditions.

Good luck
Dr. Langis Michaud, Optométriste, MSc, FAAO (Dipl)
Associate Professor – Université de MOntréal

Aimee wrote:
I have worn glasses since I was 12 and fulltime since I was 31-32.I have always had 1 pair of glasses that I used for everything.2 years ago my optometrist started me on hidden bifocals.I couldnt stand them so this time when I went back in nov I told him I didnt want hidden bifocal and just wanted my normal lenses back.So I got them(or so I thought) and I cant use them on computer at night*(I always could with all my previous glasses)These make my eyes seem blurry .I have transitions glasses for the first time could that affect them?.Also when I read now I have to take them off,cant read with them.Ive never had this problem before ever.I have always had 1 pair that did it all/So I called and told them I couldnt read with them or anything.
They said bring them back and I will pay 130.00 to put hidden bifocals in!!!I dont want hidden bifocals.I have a feeling they really messed up here and I shouldnt have to pay to correct their mistake.Why all of a sudden after all these yr s cant I read with them? Which is exactly why I got them in the first time when I was 12.
TY for any help you can give,Aimee

ANSWER

Aimee,

Since you have not mentioned your current age, I will write this with the assumption you are in your 40s, the time when most everyone needs some help with focusing up close.  I will also assume that the “hidden bifocals” are progressive lenses.

By the time we all reach our 40s it becomes difficult to see print at normal reading distances.  Those who are short sighted (Myopic) can often take their glasses off to read, but this is not very convenient in many situations.  Those who are far sighted (Hyperopic) have no choice but to get reading glasses of some sort.  Help for reading comes in several versions  -  separate reading glasses, old fashioned lined bifocals, or todays Progressive lenses (also called Multifocal lenses).

There is no going back unfortunately, we have not yet found a way to restore focusing ability as you had in your 30s.  So yes, I am afraid that you will need progressive lenses from now on.

Dr. Joan Hansen, Optometrist for CAO

Timmy wrote:
Hi, i have a question regarding prescriptions for glasses and contacts. I understand you should not be using the degrees prescribed to you for glasses for buying contacts because contact lenses sits on your eyes directly as opposed to the glasses being a few inches away.
So my question is, would my eyes get worst or some sort of negative impact if I do wear contact lenses having the same degrees as my eye glasses?
the degrees for contacts should be slightly stronger or weaker? so if you wear contact lenses that are not exactly the same degree, what are the dangers of doing so? will it be merely less clear or will it make your eye sight worsen?

Thank you for your time

ANSWER

Hello Timmy,
Yes it is true that in most cases the prescription your optometrist gives you for your glasses is different than the one given for your contact  lenses.  Whether the contact lenses are stronger or weaker will depend on the prescription.  Wearing contact lenses that are the incorrect prescription (stronger or weaker) can cause symptoms of blur, headaches, dry, uncomfortable eyes and/or spasm of your focusing system.  Furthermore, if the lenses do not fit correctly, there are many other eye-health related problems that you would be at risk for.
When purchasing contact lenses from your optometrist, he/she will ensure that you have the correct strength and fit needed, and would be happy to give you a copy of that prescription for your records.

Thank you for your question. 
Dr. Donati

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

Derry wrote:
I have been wearing progressives for a year. I am quite used to moving my head around to gets things in focus. When I read or do computer work, both eyes do not focus the same. If I get my right eye to totally focus on a word, then try my left eye, the left will be out of focus.  If I get the left eye in focus first, the right eye will be out of focus. I have had the settings checked more than once, and am told that one eye is always going to be more dominant than the other. My thought is that both sides should be equally clear. Could you let me know your thoughts please?

ANSWER

Dear Derry

You are right to expect that 2 eyes work together and with clear and equal focus on each side. There is nothing to do with the dominance of your eyes. That could be related to a misalignment of your progressive lenses, especially if you see that happening just at near. If one of the eye is not well centred with the progressive lens, you can see outside of the clear vision channel, explaining the difference in your vision.

Another possibility is a binocular vision problem, i.e. your convergence is not as accurate on one side compared with the other one. This could be checked through a regular optometric examination, with a special attention to measure the natural deviation (phoria) at far and at near. Finally, you can be affected by a weaker eye that is called amblyopic. This could lead to a difference in vision and if this is the case that would be true either at far and at near.

Having not all the details of your case, my first recommendation would be to get a second opinion in that matter and to ask another optometrist for a more complete examination of your vision and your ocular health, using proper medication to dilate the pupil and to cyclopledge your eyes. This will help to determine the real “refractive error” of your vision and to see if there is any pathology that could explain the difference between the 2 eyes.

Thanks for your interest.

Dr. Langis Michaud, OD, MSc, FAAO
Associate Professor
Université de Montréal, School of Optometry

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

Regan wrote:
My prescription is -4.5 and -5 with a small degree of astigmatism). As I enter my mid-40s I also find my close vision is slowly getting worse, especially in poor light but it’s only starting to be inconvenient, mostly when I wear my contact lenses. I found the disorientation of bifocals too much for the moment, and they aren’t quite necessary since I can peek over the top of my glasses for the most part.

I tried on pinhole glasses at the store and they corrected my vision quite effectively (while standing there and testing my ability to read fine print at the counter and see the back of the store too - I don’t know how well it would work at my computer or daily life). I’d like to know more about their uses. Having used cameras, I understand how they work in terms of changing the aperture of the eye, but I’d like to know if there are developmental risks or benefits involved, and how they can best be used. I’m not looking for a miracle to replace my glasses and contacts, but I do feel that my lifelong dependence on glasses has worsened my vision, and I can also foresee situation where using pinhole glasses would be less of a strain (like cooking while also reading from a recipe). If they would also slow down or prevent further deterioration that would be an added bonus. Thanks.

ANSWER

Regan,

It is very normal for you, in your mid 40s, to be having problems with close (near) vision, and this is always more evident with contact lenses.  Speak to your Optometrist about a change to your contacts so that you can read.    We often use bifocal contact lenses or a technique called Monovision where one eye sees close up and the other far away.

I would not recommend pinhole glasses for any sustained activity.  The strain of trying to find the little holes would negate any benefits, as well as having to change to your regular glasses in order to walk or move around your office or kitchen.  I am not aware of any scientific studies which purport the use of pinhole glasses. Most often they are used as a novelty, party trick, item.  We have not found a way to stop the changes in near vision, since they are linked to aging.

Dr. Joan Hansen - Optometrist, for CAO