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Hyperopia and Presbyopia Progression

For and about anyone having difficulty seeing near/reading.

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Lou 21 May 2018, 04:26

Hi LT Lurker

A very interesting article, thank you very much, especially the first section.


Lou 20 May 2018, 23:36

Hi Kris

Sorry, I didn't thank you for your post. Thank you very much.


Lou 20 May 2018, 16:21

Thanks very much, LT Lurker, I'll check out the article


Lou 20 May 2018, 16:20

Hi SC

To continue my previous reply.

Regarding the following from your post:

It makes sense to me that if 25-30% of the population is myopic, then a similar proportion will be hyperopic Ė so the scary thought is that when you get to 40 and youíre not short-sighted youíve still got an almost even chance youíll end up in glasses full-time for hyperopia!

I agree with your idea, but not necessarily that you'll have an almost even chance of ending up needing glasses full-time for hyperopia, as a fair number of people seem to have near, intermediate (if they use a computer, read music or have other intermediate vision requirements) and distance prescriptions, and have separate pairs of glasses or bifocals/varifocals and still not wear them full-time. As I mentioned previously, my mum is a perfect example of this, wearing her bifocals for reading/knitting and driving/tv, and nothing in between, which leads me back to my comments on on middle-distance blur. Probably there is a big difference between needing and choosing to wear.

You are probably are right that people don't notice (or care), but I would have thought that people regularly using a computer/musicians reading music, would notice (and care), and I agree that without intermediate distance glasses, the middle distance from around 2m to 40cm is probably awful for older emmetropes. Since my almost 70 year old mum wears glasses of around +1.50 for distance and around +4.00 for reading, I imagine that she must complete all household tasks and eat all meals, in a relative amount of blur.

I'm not sure about further hyperopia progression as we age either.

Thanks very much again for your very insightful and interesting post.


LT Lurker 19 May 2018, 23:30

Hi Lou,

This article bears out what you have suggested regarding presbyopic hyperopes. The problem these laser surgeons had was in the area of latent hyperopia and how they were "surprised" at how much some patients over 50 had hidden.

https://www.ophthalmologymanagement.com/issues/2002/september-2002/hyperopic-presbyopia-weighing-the-surgical-option

I'm not sure that I would like to have these guys play around with my eyes!

A lot of people suggest the Donders scale of expected amplitude of accommodation is accurate.

Not at all if these anecdotes are to be believed.


Lou 19 May 2018, 12:25

Hi SC

Very interesting, thank you very much. Regarding your rule of thumb, I'm not sure if/how much it applies to me, since my small amount of hyperopia is simple hyperopic astigmatism rather than hyperopia overall, and as is the case with simple hyperopic astigmatism, I have a plano prescription in the opposite meridan.

I'm 44, and wear the following prescription full-time owing to eye strain caused by my eyes constantly trying to focus over my small amount of astigmatism:

R: +0.50 Sph -0.50 Cyl Axis 92

L: +0.25 Sph -0.25 Cyl Axis 85

I believe that my left eye prescription falls somewhere between +0.25 Sph/-0.25 Cyl and +0.50 Sph/-0.50 Cyl, as my prescription has switched between the two over the years.

I used to have a reading add, +0.25 from the age of 38, +0.50 from the age of 40, but my optician got rid of it when I was 43, as I got a separate pair of reading glasses with a +0.50 add, and only wore them once, as I found that they didn't even work for a distance as far as my lap top, which is the only the length of my fairly short arms away, and I found them too restrictive. She said that she could give me a +0.25 add, but she didn't feel that I needed it yet. Just lately, my close vision is starting to go, and I imagine that I will need an add when I am due to have my eyes tested next June, when I will be 45. As long as I don't hold small print too close, I can read it fine with my usual glasses and even without glasses, although it is slightly blurred, in the way that I find all distances slightly blurred without my glasses.

I agree that it makes sense, that if 25-30% of the population is myopic, a similar proportion will be hyperopic

To be continued


Kris 19 May 2018, 00:25

This hyperope only made it to 39 before needing progressives (and I was told at 38 I needed them, but ignored that information until I was desperate). I wore fulltime distance correction before getting the reading prescription. My most recent eye exam gave me the following prescription L+1.00, cyl -0.25, 5 BO and R +2.00, cyl -1.25, 5 BO with a 2.25 ADD. Iíve just had a small astigmatism correction added to my L eye prescription and the cyl in my right eye just went up by 0.75.

Obviously Iím not a straightforward hyperope, but many will have signs of presbyopia in their 30s. Itís a fallacy that presbyopia only sets in after 40. Some peopleís eyes have other plans.


Kris 19 May 2018, 00:25

This hyperope only made it to 39 before needing progressives (and I was told at 38 I needed them, but ignored that information until I was desperate). I wore fulltime distance correction before getting the reading prescription. My most recent eye exam gave me the following prescription L+1.00, cyl -0.25, 5 BO and R +2.00, cyl -1.25, 5 BO with a 2.25 ADD. Iíve just had a small astigmatism correction added to my L eye prescription and the cyl in my right eye just went up by 0.75.

Obviously Iím not a straightforward hyperope, but many will have signs of presbyopia in their 30s. Itís a fallacy that presbyopia only sets in after 40. Some peopleís eyes have other plans.


SC 18 May 2018, 02:30

Lou,

Presbyopia impacts people with hyperopia different from emmetropes. People with hyperopia will suffer the impacts of presbyopia earlier Ė the rule of thumb I use is that for each year before 45 that you first realise you need glasses to read indicated +0.5 hyperopia. I first realised when I was 41 so Iím likely heading for +2.0, my wife was 43 & now +1.0 etc. Presbyopia isnít the cause it is the catalyst. It also isnít when you get the glasses either Ė I manfully held out until I was almost 44 but it didnít benefit me in any way.

So most hyperopes will be discovered quite quickly in their mid to late 40s, others will hold out to later because they will still have 0.6-1.0 accommodation and so they can self-correct for distance problem of +0.5, say.

It makes sense to me that if 25-30% of the population is myopic, then a similar proportion will be hyperopic Ė so the scary thought is that when you get to 40 and youíre not short-sighted youíve still got an almost even chance youíll end up in glasses full-time for hyperopia! I know myopia rates are rising Ė I wonder that will have a consequential drop off in hyperopia or whether a lot of it is pseudo and weíll have some myopes becoming hyperopes in later life.

I saw your comments on middle-distance blur Ė I think the answer here is that people donít notice (or care). When my wife got varifocal lenses she hadnít realised how bad her middle distance was. It must be bad for older emmetropes too - perfect distance vision, great reading vision @40cm with glasses, but the middle-distance from around 2m to 40cm must be awful, I guess they donít realise it is a problem or that there are things they can do about it. For the same reason, as a varifocals wearer, when I tried bi-focals I found them very difficult Ė distance was better, reading was better but what about all the stuff in between.

Lastly, I see people starting to wear glasses for distance when they are quite old Ė my friendís mother has just started with varifocals and she is around 70. They are weak, probably +0.5, but donít know whether this is due to some further hyperopia progression as we age, or just finally giving in to the problems sheís had for the last 15 years


Cactus Jack 16 May 2018, 15:42

Meike,

It was just a thought.

At some point, you might consider Lasik, but think about that long and hard. At 18 it is possible that your prescription has not stabilized yet. For most people, their vision does not stabilize until they are in their 20s. It is typically NOT a good idea to have Lasik until after their vision has stabilized.

Have you experienced much of a difference in your prescription over the last few years?

C.


Meike 16 May 2018, 08:56

JC, thanks for your information regarding US requirements.

@Cactus Jack thanks for your advice. I am not sure if I would want to experiment the way you described. Maybe I should let it go and just wear my glasses the way they are.


Lou 16 May 2018, 04:30

Hi

I have a question about Presbyopia, which I've thought of previously, and have been reminded about by a sighting, which I'll post later.

I fully understand how Presbyopia effects initially near vision then intermediate vision, but had not fully understood why both my parents and some of my older friends/band colleagues, initially started with reading glasses, then intermediate glasses, then distance glasses.

Following the sighting, I did a bit of research on google and found the following:

Will presbyopia affect my distance vision?

If you are emmetropic (perfect-sighted), presbyopia will only affect your ability to see close up (reading, for example) and middle vision (using a computer, for example). It does not affect your distance vision, so you will still be able to drive without glasses.

If you are hyperopic (long-sighted), as you get older and the lens stiffens, both your distance vision without glasses and your near vision will become worse. You will then need to wear separate glasses for both distance and near vision, or have bifocals or varifocals, to see clearly. Your optometrist will tell you which applies to you.

From:

https://lookafteryoureyes.org/eye-conditions/presbyopia/

Although not strictly stated in the article, if I understand correctly, which now that I think about it makes perfect sense, that before presbyopia starts, people who are long sighted to a small degree, are able to self correct it by using their ciliary muscles to provide the extra plus they need, which is greater at near, than at immediate than finally at distance, hence why they start needing glasses for these distances in this order, finally needing distance glasses, when their crystalline lens has become so stiff (possibly also their ciliary muscles so weakened), that they can no longer even provide the relatively small amount of plus that they need for distance.

In the case of my father, this makes perfect sense. He has three sisters, who all wore glasses for hyperopia as children, one full time and the other two for reading. The older two now wear glasses full-time, most likely varifocals. My Dad's mother wore glasses for hyperopia full-time from as far back as I have seen photos of her. My Dad didn't wear glasses at all until aged around 45, whereas my Mother started wearing reading glasses at around 42. My Dad's eyes deteriorated quickly, and he started wearing glasses for driving around aged 47, whereas my mum was around 52.

If I am understanding correctly, adults whose presbyopia has progressed to the point that they need glasses also for driving, have effectively spent their earlier adulthood with latent hyperopia, which has naturally been uncovered once their eyes are no longer able to provide the extra plus needed even for distance.

Considering the number of people I know who go on to need glasses for driving after starting off with them for reading in their early/mid 40s, is it truly the case that large numbers of people are self-correcting latent hyperopia, and it is actually pretty common, or is something else going on which I am not understanding?

To put it another way, if a person starts needing plus glasses for driving between around 50 and 60, did they always need this extra plus for distance and their eyes provided it (i.e. they had a degree of latent hyperopia), or do they start needing plus glasses for driving for another reason? If so, I can't optically understand this. Could it be owing to the start of cataracts for example, creating a refractive error? I have no real idea over and above someone with cataracts wearing glasses for near, owing to the glasses magnifying things and making them easier to see.

Oh, and to the troll, you have won in that I am not going to put my usual sign off greeting or name at the bottom, as I can't be bothered to see you impersonating me. I really hope that it makes you happy, to have stopped a 44 year old from being their usual polite self, and it makes you feel good about yourself.


JC 15 May 2018, 04:39

I work in the airline industry and am familiar with U.S. requirements. No (U.S.) airline I have heard of has any specific vision requirements now for flight attendants. I know some with very high prescriptions -- some with contacts and some with glasses. I even know a few with smaller prescriptions who don't wear anything at all and are seen squinting all the time. Really for an emergency evacuation it isn't an issue. I'm -4 myself and often do -9 GOC, and I think leading an emergency evacuation would be easy even at an uncorrected -9. One can easily open the emergency exits and know where passengers are to shepherded them out -- you don't have to be able to recognize their face or even identify their gender, just see there is a body there that needs to get out.

If anyone is curious about the pilot requirements, again just speaking for the U.S., it is 20/20 corrected at near, intermediate, and distance in each eye separately and together, along with a host of other things such as depth perception, color vision, peripheral vision, and strabismus. If flying in international airspace a pilot must carry spare corrective lenses but domestically even that isn't required. I know one pilot who wore -11 contacts and was also occasionally seen wearing her glasses flying -- and attractive too, defiantly worthy of the sightings thread when she wore glasses! As much as we might like to fantasize otherwise glasses and contacts are pretty reliable and for someone to start a flight with a pair of glasses in good working order to not finish it the same way would be unusual.


Cactus Jack 14 May 2018, 20:12

Meike,

This idea would be a bit of an experiment. I would not normally suggest it, but at 18, there might be a possibility.

Your prescription indicates that your Left Eye with the +3.00 in Sphere is Hyperopic. Your Right Eye with the -1.00 in Sphere is Myopic. Typically, both Hyperopia and Myopia are caused by a mismatch between the total PLUS power of each eye's lens system and the length of the eyeball from the back of the Crystalline Lens and the Retina. The distances involved are very small, about 0.3 mm per diopter. In your situation, it is likely that your Left Eye did not grow quite enough, by 0.9 mm and your Right Eye grew about 0.3 mm too much.

Your eyes develop independently as you grow from childhood. Typically, the eyes track pretty much together, but they don't have to. Because of your age I am wondering if you can Induce some Myopia in your Left Eye without appreciably affecting your Right eye.

You mentioned that you would like for both eyes to be Plus. Unfortunately, that won't work because it is impossible to Induce Hyperopia. That would require that the eyeball shrink. Eyeball growth, like bone growth, is a one way process.

If you want to try stimulating your Left eye to grow some you would need to order glasses with reduced PLUS in your Left lens.

You might start with +2.50 in Sphere to see if you can tolerate it. Then +2.00, +1.50, etc.as you get used to each reduction. If you feel very comfortable with a reduction, you might consider going down 1 diopter.

My suggestion would be to order inexpensive glasses and frames, online from an online retailer such as Zenni.

I frankly have no idea if it will work, but if you order low cost, identical frames, the changes will not be noticeable to others. Try to NOT increase the Minus in your Right Eye.

C.


Soundmanpt 14 May 2018, 07:43

Interesting topic. I well remember when I was young and before the days of contacts lenses if a young lady wore glasses at all even very weak glasses she couldn't be an airline stewardess. Back then that is what they were called and only women were hired for that job. I think they even did yearly eye exams and if a stewardess went from having perfect to needing glasses she laid off or fired. The airlines thought it was safety concern because of how critical it would be for stewardess to be able to assist passengers in getting off the plane in an emergency. And if the stewardess glasses were to come off or get broken she could be too impaired to be of any help to passengers and need help herself with getting off the plane. They finally started to relax the rules a bit and stewardess were allowed to wear glasses as long as their vision without glasses was still considered as being good enough to see with helping others. So I would assume maybe something like being at least at 20/40 for passing your drivers vision test was used. Several months ago I had to fly out of town and I couldn't help but notice that 3 of the flight attendants were wearing glasses. I managed to get a pretty good look at all 3 of their glasses. Two of them I could tell wore glasses that were clearly not more than maybe -1.75. But the 3rd young ladies glasses were much stronger and i'm sure without her glasses she would have a difficult time seeing much of anything and would need help finding her way off the plane in an emergency. This was Southwest Airlines so they surely don't have any restrictions about wearing glasses.

By the way all 3 were quite attractive.


Meike 14 May 2018, 07:34

Crystal Veil

Yes I know, but did pay my Ä50 at Pearle to do the eye exam only.

I used the info to order my glasses online.

Leuk dat je ook Nederlands bent


Crystal Veil 14 May 2018, 00:25

Meike,

in my experience, most opticians in the Netherlands are reluctant to prescribe glasses to anyone with your prescription. They say that the difference between both eyes is above the limit to get a satisfactory result (vision wise). I have exactly the same prescription as yours and they always tried to talk me into contact lenses. Opting for one contact lens instead of two would solve the cosmetic problem and also give you better vision. Glasses of +3 on both sides give you a completely different look. You might even consider trying a +4 contact lens for the left eye and wear -1 glasses for a bit of variation. A longsighted or a shortsighted look, depending on the mood of the day. Ze zullen vast wel meewerken als je het op die manier uitlegt. Succes er mee!


Meike 13 May 2018, 04:33

Is there an indication that I wasnít positive? All major dutch airlines pretty much have the same requirements. I donít know if I should go the way Catus Jack suggests, but Iíd like to see his other option as well.


NNVisitor 12 May 2018, 23:09

It's important to be absolutely positive about an airlines vision restrictions if one desires to be a flight attendant. Keep in mind that different airlines have different requirements. Their key concern is that in an emergency where glasses may be broken or lost or contact lens have to be removed or pop out the flight attendant can still see well enough to save lives. An emergency situation may never happen however airlines always have to be ready in case they do.


Meike 12 May 2018, 22:28

Thanks again Cactus Jack. The KLM requires you to not have glasses over -5 or+5. That would still work. I do agree that wearing contacts may be a problem during long flights.


Cactus Jack 12 May 2018, 06:16

Meike,

Maybe, It depends on the optician. They might suggest contact lenses for both eyes. However, before you embark on this, you might want to check on the vision requirements of the airline.

Many years ago, airlines would not hire Flight Attendants who wore glasses. I don't think that applies today.

However, one consideration about wearing contact lenses is that cabin humidity in pressurized Jet aircraft is typically low. Often, contact lens wearers experience discomfort on long, high altitude flights.

May I suggest investigating the airline requirements before we go too far with this. I have an idea that does not involve contact lenses that might work at 18.

C.


Meike 11 May 2018, 22:30

Cactus Jack,

Would any optician cooperate with this?

I have never worn contact lenses.


Cactus Jack 11 May 2018, 20:39

Meike,

If you wear a +4.00 contract lens on your Right eye, your glasses prescription would beL +3 cyl -025 110 R +3.

Have you ever worn Contact Lenses?

C.


Cactus Jack 11 May 2018, 20:30

Will,

You still did not mention your age. That is important. Most people, who don't normally wear glasses find that as they reach 40, their arms get too short for them to be able to focus on the text. If they are trying to read the very small text on smartphones and tablets, it may happen before they reach 40. If they are a little Hyperopic (farsighted) it might even happen at an earlier age.

Vision actually occurs in the brain, the eyes are merely biological cameras. The +1.00 glasses will make text a little larger and blacker, but it also relieves you Ciliary Muscles of some of their workload. Your brain can also correct slightly blurry images, if it knows what something is supposed to look like.

If presbyopia is truly becoming a nuisance AND you wear the +1.00 glasses when you are reading AND you read a lot. Your Ciliary Muscles will begin loosing their tone pretty quickly. Probably in just a few months you will want to go up to +1.25 or +1.50.

Many people who don't need glasses for distance or have exceptional distance vision actually have what is called Latent (May or hidden) Hyperopia. Hyperopia is the ONLY refractive error you can correct internally, using your Ciliary Muscles and Crystalline Lenses, typically without your even being aware that you are doing it.

A clue that you may have some Latent Hyperopia is when you first put on the +1.00 glasses, everything beyond 1 meter or about 40 inches is a bit blurry. But, if you have been reading a while with the +1.00 glasses and you look at something in the distance, it is less blurry than it was earlier.

May I as a few specific questions?

1. What is your age?

2. What is your occupation?

3. Do you use a computer display in your work?

4. About how many hours per day do you read or use a computer?

5. Where do you live? (country)

C.


Meike 11 May 2018, 09:17

Cactus Jack,

Thanks for your reply. I will do my best to answer your questions.

1. Iíd like both eyes to be plus

2. May I ask your age? 18

3. Your Occupation: stocking shelves in a supermarket, but go to school to become a flight attendant.

4. Where you live? (country) the Netherlands

5. Can you provide your complete prescription? L +3 cyl -025 110 R -1

Hope this helps.


Will 11 May 2018, 07:44

Thank you CJ for your response. Yes I have a lot of questions. I don't yet know what it is like to "need" glasses to read. Although I got the (+1.00) readers and they make the print a bit bigger and darker, I don't feel that I need to use them as I can see ok without..unless I wear them for a while and then I take them off. I can still read ok, but I notice the softer blacks and only slight blur (which I didn't have before)on very tiny print. So it seems, according to my friend, that if I continue to use them my ability read without glasses will go, I will NEED them. AND she says that over time, for her about 2 years and 2 increases later she went full time...distance too. I presume that if I don't use the readers I will eventually need help with close, but don't want to rush that. Is there any rule of thumb as to how long it takes for the muscles to "decondition" till I can't read without? Do readers cause worsening distance vision too? What to do? Thanks for enduring my rant.


Cactus Jack 10 May 2018, 23:02

Weirdeyes,

A while back, I devised a Simple Prism Test. I have posted it here and also on vision and spex on several occasions. The test is based on Sir Isaac Newton's definition of 1 Prism Diopter as that amount of prism, which will bend a ray of light 1 cm at a distance of 1 meter.

The test is fairly easy to perform, but it does take some preparation using some adding machine paper tape, a marking pen with a wide tip, a tape measure that is about 25 feet or about 10 - 15 meters, depending on which unit of measure you prefer, and some easily removable painter's tape.

You have to calibrate the paper tape to match the selected distance, from which you will be observing.

Here is he test. You might want to repeat it over several days as Ben did.

SIMPLE PRISM TEST

It is not hard to measure the amount of prism it would take for full correction. All it takes is some adding machine or cash register tape, a marking pen, some painters or masking tape (ideally with very weak "stick-um" for easy removal) and something to measure distances.

It is a little easier to work with metric measurements, but you can do it also with inches and feet. You just have to do a little more math for conversions between the two.

This test is based on the definition of 1 prism diopter as: "That amount of prism that will deflect a ray of light 1 cm at a distance of 1 meter (100 cm)".

Ideally, this test is done without any prism correction in your glasses, but you need to be able to see some calibration marks on the adding machine tape with reasonable clarity. If you can't see the marks without glasses, you can still do the test, but you must account for the prism in the glasses.

1. Select a fairly blank wall that you can attach the calibrated adding machine tape to, using the painters or masking tape.

2. Decide where you will stand or sit while doing the test. Between 3 and 4 meters or 10 and 14 feet works best. Measure the distance from that location to the wall selected in Step 1.

3. Calculate how much displacement 1 prism diopter represents at the distance measured in Step 2.

4. Using the marker, mark the adding machine tape with major divisions 5x the distance calculated in Step 3 and optional minor tick marks at 1 prism diopter intervals. The marks need to be big enough to see easily from the distance in Step 2. You might want to identify the major divisions as 0, 5, 10 etc. Note: Some large bold markers will bleed through the adding machine tape and permanently mark the surface you are using as temporary backing for the adding machine tape. Test and take appropriate precautions to prevent damage by the marker ink.

5. Attach the adding machine tape, stretched out horizontally, to the wall selected in Step 1.

6. On another short piece of adding machine tape mark an arrow lengthwise and attach that piece of tape to the wall, vertically, so the arrow is pointing at 0.

You are ready to do the test.

7 Place yourself at the location selected in Step 2, let your eyes relax so you see double and note where the "0" arrow appears to point in the displaced image. Try this test several times during the day and at varying degrees of fatigue. Make a note of your results.

8. If you are wearing glasses with prism, adjust the readings in Step 7 for the total prism in the glasses.

This test will work with horizontal prism (Base Out or Base In) or vertical prism (Base Up or Base Down) by the placement of the long tape and short tape. Often both horizontal and vertical prism exist at the same time.

Note: It is sometimes difficult, if small amounts of prism are involved, to tell if the prism correction needs to be Base Out or In, Up or Down. You may be able to tell by noticing which way the images are displaced when you block the eyes alternately. For example, if you cover the right eye and the image from the left eye is on the left, you probably need more Base Out.

Please Let me know if you have any questions and if this works for you.

C.


Weirdeyes 10 May 2018, 19:46

Cactus Jack

How do you measure prism? A while ago people told me I have an exodeviation of 8 diopters. Right now I have glasses that are one prism diopter in each eye. I can still go without the prism. Iím starting vision therapy very soon. They want me to wear glasses that have only half a prism diopter in each eye.


Cactus Jack 10 May 2018, 16:41

Ben,

I don't think there is any way to predict where your need for prism will wind up. 25 is reasonable.for this test. ECPs typically try to prescribe the least prism possible. The rule of thumb that many ECPs seem to use is to prescribe 1/2 the measured value. I would not get very excited about 6 or 7 BO in each eye. I am wearing 7/7 BO while I write this at 6:30 pm. However, if I get very tired, I may have to switch to some glasses that have more prism to not have double vision. There is such a thing as Fatigue Esophoria.

One of the problems you run into with prism is that making glasses with significant t prism seems to be a lost art. My experience has been that if when you get above about 10 prism diopters in each eye, Visual Acuity seem s to suffer a bit. It was this loss of VA that caused me to dig deeper into optics and vision. I have a theory about why the VA decreased, but have never been able to confirm it. Some people don't seem to notice it.

C.


Ben 10 May 2018, 13:04

Hi Cactus Jack,

Thank you very much for your detailed response. The explanation of VT is helpful. I suspect that one would need to do it persistently to main fusion without prism correction, since they eye muscle would become "untrained" again?!

In any case, I followed your advice and did the prism test over a few days (in order to establish a somewhat reliable measure). In fact, most of the issues I have with visiting eye doctors is that they usually judge prisms based on a single test, as opposed to a series of tests.

I believe I did everything correctly, and the results of the test point to an eso deviation of around 25 prism diopters, so considerably higher than my current 6BO! In your estimation, is that realistic? I didn't believe this at the beginning, but repeating the measurement over multiple days did not make a difference (-/+ 2 dptr).

Looking at the results, my deviation is around 4x the current value. In your experience, would this roughly be the end of the journey, or is that likely to increase even further if I start to increase the current correction?

Thank you for your explanations! They are very helpful to get a better grasp of strabismus.

Ben


Cactus Jack 10 May 2018, 12:47

Meike,

There is a 4 diopter difference between your Right and Left eye. That can cause a difference between the two lenses in your glasses and a difference in image size on your retina. Unfortunately, there is no simple way to make the lenses in your glasses appear the same except by wearing a contact lens on one eye, if you prefer glasses or wearing contact lenses with different prescription for each eye.

May I ask a few questions?

1. If you decide on glasses, would you prefer both eyes to have + lenses or - lenses?

2. May I ask your age?

3. Your Occupation?

4. Where you live? (country)

5. Can you provide your complete prescription?

Answers to the above affect our suggestions.

I understand your desires, but a difference between the prescription in each eye is pretty common. Usually, if is less than 4 diopters, but sometimes it is even more than 4 diopters.

C.


Meike 10 May 2018, 07:57

Hi, I recently got glasses L+3 and R -1. I love wearing glasses, but donít like the ďuneven look. Is there a way to make my glasses look more even?


Cactus Jack 09 May 2018, 21:59

Will,

Pretty typical starting place.

You did not mention your age. That is important, but it does not spell the whole story.

Probably 99.9999% of the human population develops Presbyopia (literally Old Eyes). Presbyopia actually starts in childhood, but does not typically become a problem until the late 30s or early 40s. The idea that 40 is the "magic" age is a myth. It depends very much on your genes and your vision.

Your eyes have a built in "Auto-Focus" system consisting of the Ciliary Muscles and the Crystalline Lenses. In childhood your Crystalline Lenses have the consistency of freshly made gelatin dessert. The very tiny Ciliary Muscles in your eyes can easily squeeze your Crystalline Lenses to increase their already considerable PLUS power even more to effortlessly focus very close. The amount of extra PLUS you need to focus close can easily be calculated by dividing the distance from your eye to the target book or display into 40 if you like working with inches or 100 if you like cm. For example, a typical reading distance of 16 inches or 40 cm requires an additional +2.50 to focus.

As you get older, the Crystalline Lenses get stiffer and at some point it is harder for the Ciliary Muscles to squeeze them and it is very tiring to squeeze the Crystalline Lenses for focusing close. At that point, you need a bit of external PLUS help. If your need +2.50 to focus at say 16 in/40 cm OTC readers can supply +1.00 and your Ciliary Muscles and Crystalline Lenses can supply the other +1.50. However, there are two downsides.

The most obvious one is that the +1.00 glasses have the optical effect of making your a bit Nearsighted or Myopic, which makes distant things blurry. The more important downside is that the OTC glasses relieve your Ciliary Muscles of some of their workload and they get less exercise than they normally would. For their size, they are the strongest, best exercised muscles in your body. Like all muscles, if you don't use them, they loose their strength and conditioning. Between the stiffening of your Crystalline Lenses and de-conditioning of your Ciliary Muscles, Presbyopia will seem to increase rapidly. The stiffening process occurs slowly, but the de-conditioning of the Ciliary Muscles happens much faster. As occurred in your co-worker.

I hope this helps, but I suspect you have more questions.

C.


Will 09 May 2018, 07:13

So I did ok at my exam but the dr said if I use glasses when I do a lot of close work I would find it relaxing. Presently I When he put the card on the stick for the close test I could read the bottom line, but as he clicked the machine I remember the small print becoming more clear by the click. Although I can see close ok without glasses, I do tire easily while reading.

He said the downside to getting glasses for close is that they would blur everything far away, which what happened when he removed the card from the pole. He said for now I could use OTC but not from a $ store. He said to find a pair that say +1.00 or if I want +1.25. Is that a normal starting prescription? I used them mostly at home and he was right. When I took them to work a co-worker told me that when she started wearing readers but within 5-6 months she couldn't read without them, and that would likely be the case if I keep wearing them. Then she said within a year or two when I think I might need them stronger they will add in a prescription for distance. When she got hers, at first the distance wasn't clear but soon she was full time, and now can't live without them. How can I know if this is typical and if this is the road I am on.


Cactus Jack 06 May 2018, 18:12

Ben,

I did not answer all your questions.

With out your glasses, You will have better vision in your Right eye because it has the least refractive error and requires the least accommodative effort to compensate. Because of your Astigmatism and need for -2.00 Cylinder, your vision is probably pretty blurry without correction.

There are 3 muscle pair (6 muscles) on each eye, they move in opposition because fundamentally, muscles can only contract (pull) and relax. They have no ability to "push". One pari moves your eyes left and right, another moves them up and down, and the 3rd moves your eyes obliquely.

Eye position is controlled by what I call the Eye Position Control System (EPCS) in your brain. Signals from the EPCS travel to the muscles over the Cranial Nerves.

Eye misalignment can be cause by problems in the EPCS, the Cranial Nerves, or what is called Muscle Imbalance. Double Vision problems can be caused by any of the 3 or any combination. Muscle Imbalance is typically the "catchall" because it is rare to be able to locate the actual cause or causes, unless it is related to an obvious brain injury.

There are only 3 ways to correct double vision issues. Glasses with Prism, Muscle Surgery which may or may not work, or Vision Therapy which may or may not work.

Vision Therapy for double vision is pretty simple. you can even build the rig your self. It is typically a fairly long looped string with a small ball or large bead (target) attached. You loop the string around a "distant" drawer pull or similar object and move the target from close to away from you while tracking it with both eyes. You should have little problem fusing the images of the target when it is close, but as you move it away from you it will get harder to keep the target fused. The idea is to try to strengthen the Lateral Rectus (outside) muscle and weaken the Medial Rectus (inside) muscle.

Part of the problem you will have is that the difference in strength is small. The easy solution is to just wear prism in your glasses, but there are downsides that you have discovered and some you may not have realized.

Unfortunately, Prism tends to increase. I believe that there are two elements involved in this increase, but please remember that I am NOT an ECP. My background is Electronics and Computers, but I have been dealing with Double Vision and Prism for about 40 years and learning all I can about it. I have tried Therapy, Muscle Surgery, and Prism.

One of the two elements are that the EPCS seems to be very adaptable. Ideally, the EPCS is "happy" with the eyes pointing straight ahead for distance, but it is very easy for the EPCS to adapt to the eyes being converged or diverged when relaxed. The other is that when you wear prism that allows your eyes to turn inward, it soon become the relaxed position and when you focus close, your eyes have to converge more from there which strengthens the inside muscle and relaxes the outside muscle.

People who are Hyperopic sometime have a problem that further complicates the situation. There is an interconnection in the brain between the ECPS and the Focus Control System. This interconnection is beneficial because it causes the eyes to converge when you focus close, so you don't see double. A person with uncorrected Hyperopia may experience a tendency for their eyes to converge, even when they look at distant objects, because they have to add PLUS internally to clearly focus distant objects. This can be exacerbated by Astigmatism, because no matter how hard the Ciliary Muscles are commanded to focus the image, it can't

Vision Therapy is typically offered by Therapeutic Optometrist or perhaps Pediatric Ophthalmologists. They also work with adults who have Double Vision problems.

You asked about Double Vision when you look to the side. That can be caused by one eye "hitting the stop" before the other one. If the Central Axes of Vision is parallel, your eyes may reach the limit (the stop) of their side to side motion at about the same time. When the Axes are not parallel, one may hit the limit before the other.

Another thing to remember is that the EPCS is an amazing system. Think about what it has to do. In engineering terms, it is an Open Loop servo system. It uses the images from each eye as its primary input It appears to try to match vertical edges in the images for adjusting eye position, horizontally and horizontal edges for adjusting eye position, vertically. When it gets it right, the images are fused and the visual cortex can construct a 3D image in your brain. If it can't identify sharp edges to match up, the eyes either wander or the brain ignores one image by closing one eye. That is one reason sharp focus is desirable to minimizing double vision problems.

It is typically not necessary or desirable to fully correct double vision issues. All that is often necessary is to get the images into the ECPS's "range" and it will do the rest. A rule of thumb ECPs use is 1/2 the measured prism.

I hope I have not confused you too much.

It is not uncommon for people with Hyperopia to need some focusing help before they reach the mythical age of 40

C.


Cactus Jack 06 May 2018, 16:57

Ben,

You can use your glasses with prism you just need to allow for for the prism you are wearing.

For example, if you do the test with a total of 6 BO and you measure 10. your total prims will be 16 BO.

Determining which direction the Base needs to be can be a little tricky. You know that you need a total of 6 BO. Try covering each eye individually and notice the relationship of the images. With BO prism, the image from the Left eye will appear to the Left of the Image from the Right Eye.

I hope this helps.

C.


Josue 06 May 2018, 13:11

Don Lemon looks great in his lined bifocals


Ben 02 May 2018, 14:57

Hi Cactus Jack,

Thank for your explanation. This is quite helpful. I think you are right. My eyes tend to cross as far as I know (and can see without glasses).

Given the choices, I guess prisms in glasses is my current option. I find it hard to imagine, but how does Vision Training work? I know about the patching of one eye for younger people, but I don't think that is what you mean.

Regarding your questions, I will answer those in the same order:

1.) Prescription

The glasses I am wearing have the following prescription:

Left: +2.5 sph, -2.25 cyl, 3BO

Right: +2.0 sph, -2.0 cyl, 3BO

One observation: Even though both eyes nearly have the same prescription, my right eye has a better uncorrected vision if that makes sense. So, if without glasses, I always close my left eye.

2.) Country

Sweden

3.) Age

36 years

4.) Duration of prism wear

I have worn prisms for around 5 years now.

5.) Why is was prescribed prism

I was prescribed a prism in my right lens when I had trouble reading (problems focusing). Even though it was only addressing the reading problem, I quickly needed it at all distances, but could still function with contacts.

6.) Occupation

Teacher

7.) Sports

The sports involve jogging, swimming, diving and climbing. Especially for jogging and climbing depth perception is quite important.

8.) Head injury

I never had a concussion on my head. In fact, in the beginning I didn't have any double vision problems.

I hope that gives you sufficient detail about my situation. In the past I have seen a number of ECPs (I moved a lot), and many had different suggestions, but all prescribed prisms.

I found your prism test on this site. I will try to give it a go, but I need to see if I have some glasses without prisms that are somewhat useful.

Thanks,

Ben


Cactus Jack 01 May 2018, 21:23

Ben,

I am not an Eye Care Professional, my background is Electronic Engineering and Computers. I have been wearing BO prism in my glasses for over 30 years and have experienced what you described about double vision and studied the problem from an engineering point of view for many years.

Over Convergence can have several causes. It is often referred to as Muscle Imbalance, but it can have other causes.

Each eye has 3 opposing muscle pairs. One pari moves the eyes left and right, another pair move the eyes up and down, and the 3rd pair moves the eyes obliquely for a total of 12 muscles. There are nerves, called the Cranial Nerves that go from your Eye Position Control System (EPCS) (my name) in your brain to the Eye Positioning Muscles. If you think about how you can move your eyes and also how you CAN'T move your eyes, it becomes apparent that the EPCS is VERY sophisticated.

Strabismus, which is the general medical name for any condition where your eyes don't track properly. Over Convergence can have causes in the ECPS, the Cranial Nerves, or actual difference in the strength of each muscle in a muscle pair, which is true Muscle Imbalance. It is likely that you have a subset of Strabismus called Esophoria, where your eyes try to turn inward, but with effort and concentration, you can sometimes force them to track together and fuse the two images. Esophoria can be a nuisance and even a hazard if you loose fusion at an awkward visual moment, as it did for me on a dark night on a black top country road where there wear very weak visual clues. Scared me badly. It was not the first time my eyes broke fusion, but never before in a dangerous situation. As you did, I closed one eye and was able to navigate the road safely until I reached civilization and lights that allowed me to fuse the two images and keep them fused.

I believe I can help you understand what is happening and perhaps give you some ideas about what to do. However, there are really only three things that can help the situation.

Prism in your glasses

Vision Therapy

Eye Position Muscle surgery

If the problem is caused by the Cranial Nerves or the EPCS, the only "simple" surgery that can be done is on the muscles.

May I ask a few questions?

1. What is your complete prescription?

2. Where do you live? (country)

3. What is your age?

4. How long have you worn prism in your glasses?

5. What were you symptoms that prompted your ECP to prescribe Prism?

6. What is your occupation?

7. You mentioned sports, which ones?

8.. Have e you ever had a concussion or serious blow to your head?

I would also like to suggest a "Simple Prism Test" I devised. You can do the test at home with a few simple items, if you are interested I will post it. The test will give you an idea of how much prism you need and what to expect in the future.

I look forward to your response. If you would prefer to discuss this privately, you can contact me at cactusjack1928@hotmail.com

C.


Ben 01 May 2018, 09:26

Hello,

I am farsighted and have 6BO prisms in my glasses and always wear some sort of correction due to considerable astigmatism. In summer I usually wore contacts for sports activities, but now this time after a long winter period during I had only worn glasses, I think I can no longer wear those.

While I still can pull my eyes straight (with or without correction), I can only do this consciously and for a short amount of time. So basically, my eyes are constantly falling back into double vision, which is even worse with contacts, because I now have two sharp images. When I look to the left or right I have constant double vision and cannot fuse the images at all. I don't have any glasses without prisms with my current correction, so I don't know if that is different.

I had been wearing this corrections for a few years now, but I pretty much have to close one eye all the time when not using the glasses. Knowing that I cannot even do basic things without glasses anymore makes me feel quite impaired.

Is that normal, given my low amount of prism correction? Is is possible that my somewhat latent deviation has become permanent?

I thought this would only be the case for stronger prescriptions...


SC 29 Apr 2018, 08:11

Onlooker,

The brain is very powerful. I can repeat this but with glasses - so left eye under corrected, right eye over corrected so can't see with either but crystal clear with both. Brain just seems to need enough info the construct the image.

Possibly suggests that your wife's eyes are uneven.


Onlooker 25 Apr 2018, 00:01

My wife was testing her eyes while reading a book. She noticed that she could see nothing with her eyes individually while she could see just fine to read with both her eyes open. I should mention that anneye test have that she needs +2.50 for close up vision while she can function fairly well without correction apart from difficulties with very small print. Any explanations ? Thanks


Onlooker 25 Apr 2018, 00:01

My wife was testing her eyes while reading a book. She noticed that she could see nothing with her eyes individually while she could see just fine to read with both her eyes open. I should mention that anneye test have that she needs +2.50 for close up vision while she can function fairly well without correction apart from difficulties with very small print. Any explanations ? Thanks


Lou 23 Apr 2018, 18:08

Best wishes to all genuine readers.


Lou 23 Apr 2018, 09:40

Here they go again.

What is wrong with people on here?

I've got better things to do than to just post either Best wishes or All the best.

Shame they haven't either.

Anyway, now that I've pointed out to genuine readers that these posts are not from me, I have no intention of feeding the troll/trolls any further.

Best wishes to all genuine readers.

Lou


Lou 23 Apr 2018, 06:09

Best wishes


Lou 23 Apr 2018, 04:50

It looks like someone has impersonated me, after my last genuine post, for what reason however, I cannot imagine.

Best wishes

Lou


Lou 23 Apr 2018, 01:00

All the best


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