The Pros and Cons of Mini Monovision
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In view of the recent posts with misinformation about Mini-Monovision I thought I would post my experience with actually having Mini-Monovision. I first used monovision when I was wearing contacts for distance vision and I got to the age where presbyopia started to become an issue. Taking contacts out to read, and then putting them back in again, is not really a viable option, so with the help of a contact lens fitter I set one eye up for closer vision and the other for full distance. It worked very well for me, but with all of the issues associated with wearing contacts. I did it again for about 18 months after I got my first cataract surgery with a monofocal IOL set for full distance, and used one contact for the near eye. That worked well, so I proceeded to do it with my second eye using an IOL. I ended up at -0.25 D in the distance eye and -1.40 D in my near eye. Astigmatism compromises my vision a bit in the near eye, but all in all I am extremely satisfied with the outcome. I would not hesitate to do it all over again. The only thing I would do differently would be to get a toric in the one eye that turned out needing it. So what are the Pros and Cons of doing it?
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Cons:
- First you have to accept a slight decrease in distance visual acuity as at full distance you will not have much binocular summing effect. My distance eye alone is 20/20+. If both eyes were done for distance, I expect my binocular vision would be 20/15. So, I did give up half a line of visual acuity.
- From my minimum distance of vision at 8" out to 18" I do not have much binocular 3D vision. I have threaded a needle, but I think if one was sewing for hours, some +1.25 or so reading glasses would make it easier. From 18" out to 7 feet or so, I have very good binocular vision. I would expect that monovision would not make for a good excuse for swishing on a tennis or golf swing.
- For reading very fine print in dimmer light you will likely need reading glasses, or a light. I use some +1.25 D readers perhaps once a week or so. I don't bother bringing glasses with me when I go out shopping or pretty much anywhere. I have had no trouble reading menus in dimly lit restaurants. I may put readers on momentarily once a week or so, for a particular task. But, they come off immediately as I dislike looking at anything of any distance with them on.
- I drive at night in the city, but for safety purposes I do wear a pair of prescription progressives when I drive out of the city on dark roads at night. I worry about a deer or moose coming out of the ditch and not having time to see it. I may wear my prescription glasses once a month or so.
- You may have trouble finding an Ophthalmologist that will work with you to get properly fitted with the correct IOL powers to achieve good monovision. Some just do routine distance vision in both eyes without even asking what you want. Some seem unaware of how it works. And I don't like to play the conspiracy theory card, but I suspect some find the "premium" lenses much more profitable than doing monovision. Monovision just needs standard monofocals which are the lowest cost and I'm sure the least profitable for them.
- If you have difficult eyes with prior laser surgery, or are at the extremes for myopia or hyperopia, it can be more difficult to hit specific refraction targets needed for monovision. In this case your will want to have a surgeon that will be very careful selecting IOL Power formulas, and making sure the power is as correct as possible. You may also want to consider surgeons that use the Alcon ORA system to measure the power during surgery to ensure higher accuracy.
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Pros:
- Aspherical monofocal lenses bring all the light to a single point and for that selected point give the highest visual acuity. With a monofocal each eye is set to a different distance. Normally the dominant is set for distance (0.00 to -0.25 D), and the near eye set for -1.5 D, or about 2 feet. This gives the brain two options for vision, and with each eye there is quite a wide range of distance they are still effective at while being off peak. The brain does a good job of blending the images together as one.
- Compared to multifocal (MF) lenses and extended depth of focus (EDOF) lenses an aspheric monofocal has a high contrast sensitivity at the peak focus point. So this gives maximum contrast sensitivity in the distance eye at night for driving, while the other eye can provide maximum contrast sensitivity up close, like when reading a menu in a dimly lit restaurant.
- Monofocal lenses, unlike MF and EDOF lenses have very minimal optical side effects like halos, flare, and spiderwebs around point sources of light at night.
- Monofocal lenses have the lowest price and in many jurisdictions it is at no cost. This compares to MF and EDOF lenses which have a premium price in the range of $5,000 to $6,000 a pair.
- If the focus point differential between the eyes (anisometropia) is maintained in the 1.25 to 1.5 D range there is minimal impact on the ability of the brain to blend the two images. In the past some have used full monovsion with anisometropia in the 2.0+ range. This gives better reading, but at a cost. This practice has been pretty much abandoned in favour of mini monovsion (1.25 to 1.50 differential).
- With MF and EDOF lenses you kind of roll the dice and hope to get what you expect. If you do not and are unhappy with the outcome, it may be more difficult to correct the issues with eyeglasses. You can't get eyeglasses that will undo the multiple focal points built into a MF lens, or unsmear the stretched focal point of an EDOF. However when you use monofocal lenses to do monovision your eyes are easily correctable with eyeglasses. Prescription glasses are always a safe plan B that can be counted on.
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Summary
My experience is that Mini Monovision is one of the "Best Kept Secrets" in the Ophthalmology field. Some can't be bothered to tell you about it. Some don't seem to know much about it. Some don't want to be under pressure to hit a specific target for myopia in the near eye. And, unfortunately some only want to do premium lenses with their associated higher profit margins.
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I would suggest if you are interested in mini-monovision there are a couple of critical questions to ask when looking for a surgeon. One of course is to ask if the surgeon does monovision and is willing to work with you on it. The other is to ask what brand and type of lenses does the surgeon use. Some a locked into one specific manufacturer, and others are locked into premium lenses only.
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And for those that suggest monovision is unnatural consider that man has been around for about 200,000 years, while eyeglass correction has only been available for less than 1,000 years. Our brain has evolved to use the images from two eyes and put them together for the best combined image. And also consider that it is not only used for IOLs, but it is also commonly used with contacts, and also with Lasik surgery to get closer vision. They don't use Lasik to give you a multifocal eye, they use it to give you monovision using two eyes.
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I hope that helps some, for those who are considering this Best Kept Secret option for IOLs.
11 likes, 250 replies
s56454 RonAKA
Edited
I'm a 51 year-old with PSC cataracts in both eyes. I've never worn glasses, never had my eyes tested, they just always worked. I don't wear sunglasses - I find glasses give me a pressure headache.
Last week I had my first surgery doing what the specialist recommended to achieve an outcome I would least hate: blended vision with Eyehance; dominant set for distance, other eye set for some kind of near/intermediate, based on what the outcome is when my distance eye is fully healed in six weeks. This would give the best chance of glasses freedom for most of the time.
I was given the option of multi-focal lenses out of pocket, but I didn't want to risk the potential positive dysphotopsia issues with halos etc. That was about the extent of the research I did before I went and had it done.
I subsequently found this forum after the surgery because I have negative dysphotopsia in the operated eye - which I was told can happen and usually resolves - but I found it quite distressing all the same.
I have no stats or figures to give you on what the surgeon was aiming for - I just trusted my surgeon and went for it. I was 6/9 in good eye and 6/13 in worst eye, but given extent of cataracts had better vision than would be expected. That's all I know. Driving had become scary at night for me with starbursts and glare and poor depth perception.
1.5 weeks after surgery and this is what I'm finding in my distance eye.
What I consider to be 'distance vision' - i.e. looking out in the distance - isn't crisp. What I consider to be 'intermediate vision' - 1 to 4 metres - is extremely crisp. What I consider to be 'near vision' - reading and computer work varies depending on light. I can use the computer on my desk and see my dashboard without glasses, no problems. If I put my laptop on my lap it needs to be about arm length away to be sharp. I'm little, so my arm length is 60cm. Even at 50cm, it's still readable - but I can tell I've hit the limit of the lens. I need low powered readers for my phone at night, but in the day I find I can read it quite well, so long as I hold it further away than I would normally.
I would value the perspective of people on this forum - and particularly those who otherwise had no eyesight issues - about the things should I do and info I should I seek out before my follow-up in six weeks to make sure I make a well-informed decision on my second eye.
Thank you.
Lynda111 s56454
Posted
I think you will get more replies if you started your own separate discussion thread.
RonAKA s56454
Posted
The most important thing you should do is get an eyeglass refraction at 5 weeks to determine where you ended up with your first eye. Ideally this is with an optometrist independent from your surgeon's practice. The refraction is essentially a report card on how well the surgeon has performed. Your want it to be independent. From what you describe it sounds like you ended up somewhat myopic instead of close to plano (20/20+ distance vision). But the refraction will tell you where, with accuracy.
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It sounds like you are 1 week post surgery and what you are currently seeing will likely change as the eye heals. That is the reason for waiting until the 5 week refraction.
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The next thing you should do is become familiar with the diopters measure of vision. Near, intermediate, and distance is very subjective. Diopters is a measure of what is required to give you distance vision, like an eyeglass prescription. 0.00 D is perfect, about -1.0 D is intermediate, and -1.5 D is not perfect near vision but is often used for mini-monovision.
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Once you find out your actual refraction on the first eye, you should be able to set an appropriate refraction target for the second eye. If the surgeon has missed on the first eye, they should be able to correct their calculations to be more accurate on the second eye.
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Hope that helps some,
Lynda111 s56454
Posted
Your negative dysphotopsia should soon eventually resolve, but sometimes it takes months.
s56454 RonAKA
Posted
Thanks very much for these helpful suggestions. Prescriptions and diopters is a whole new language for me.
s56454 Lynda111
Posted
Thanks Lynda, I certainly hope so.
RonAKA s56454
Posted
There are some things to do, if you want to consider mini-monovison. AFTER your eye measurements are taken on your second you could get a contact to correct this eye to -1.50 D. That should make you eyeglasses free and let you test drive monovision.
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After you get the refraction on your first eye and determine where it actually landed you could do some testing on it for reading. An IOL has no accommodation and is a bit different than a contact in a natural eye that still has some ability to focus closer. If this eye turns out to be -0.50 D for example you could test some over the counter readers. A +1.00 D reader would make the eye behave like a -1.50 D. A +1.25 D would yield -1.75 D. The idea would be to use a Jaeger chart (can be found at the All About Vision site) at 14" to determine how much myopia you want in the second eye. Because the IOL eye has no accommodation this will be a more realistic test of what your vision will be like for the near eye.
s56454 RonAKA
Posted
Thank you very much Ron for these really helpful suggestions. As it turns out I was due a check-in with my surgeon to see how early healing/results are, which I've now had.
Her report was: vision was 6/7.5- in her right eye improving to 6/5 with a correction of -0.50 / -0.25 x 155° (whatever that means).
Surgeon said that I currently have a slight myopic surprise, but this may resolve spontaneously over the next two to three weeks.
I am finding my steroid eye drop regime is causing some eye blurring/irritation so I don't know how much that might be messing with things.
As you suggest, I will get an independent refraction at 5 weeks when I've healed and come off the drops to see where I've landed.
My near vision is currently much better than I was anticipating - although I can tell my other eye, as bad as it is, is still giving me a near boost - and I think I'd be loathe to lose it.
RonAKA s56454
Posted
That is not too bad. The numbers mean your sphere correction is -0.50 D, and your cylinder correction is -0.25 D at an axis of 155 degrees. This is a bit of a myopic miss to the myopia side. That is better than a miss to the hyperopia (far sighted) positive side. That hurts both distance vision and near vision.
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Your correction can be converted to a spherical equivalent basis by adding 50% of the cylinder to the sphere. This combines the sphere value with the astigmatism (cylinder) to give you an overall single number of -0.625 D. That will hurt distance vision some, and hopefully as the eye fully heals it will get better. It should like it has improved some since your first impression.
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If you want to buy some dollar store readers you could try some +1.0 D ones and use them with your new eye only to see you what that is like for reading vision. That would put the eye at -1.625 D, and in the range of what is likely needed for the near eye with blended vision or mini-monovision.
RonAKA
Edited
We just came back from a south sunny vacation this past week. One thing I found about my mini-monovision (SE -0.375, -1.625) is the limit of my reading. During the evening dining, I could not read most a la carte menus. The dimmer light combined with small font on the menus was just too difficult. And, I did not bring my reading glasses or prescription progressives. There was a couple of solutions however. One would have been to use the flashlight on my iPhone. However the one that I found most convenient was to use the resort app which had PDF versions of all the menus. The backlit screen on the phone was easy to read with the PDF document zoomed to provide normal text size. That worked well.
phil09 RonAKA
Posted
I think this example shows that while your reading vision may not be ideal, it must be pretty darn good if this is one of the few things that require glasses or a workaround. I think a large majority of restaurant menus are on the internet nowadays.
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Speaking of phones, do you find it helpful to get the largest available screen size? I'm thinking I will want to upgrade when I lose my small-print reading vision.
RonAKA phil09
Posted
I have an old 8+ iPhone with a 3"x5" screen area. I think for convenience of carrying it, I might be tempted to go a bit smaller. Having a lit screen helps a lot in reading smaller fonts. I find the white text on a black background the hardest to read, but I can do it without expanding the font size or zooming in.
phil09 RonAKA
Posted
I don't think they even make iPhones that small anymore, do they?
I generally find it convenient to carry the big phones. Even the largest ones are much smaller than my pocket. But good to know you are able to read a small model comfortably with your mini-monovision.
RonAKA phil09
Posted
I had an iPhone 7 for a while and liked it a lot better than my 8+. It was more compact to carry in my pocket. I will hang on to my 8+ for as long as I can. I never really wanted an iPhone in the first place, but I kind of got pushed into it so I had compatibility with my hearing aids. At the time the aids I got were only compatible with Made for iPhone (MFi). When I replace my hearing aids I may switch back to an Android phone. My iPhone is the only Apple product we have in the household.
phil09 RonAKA
Posted
Heh. I can relate - I'm required to use an iPhone for work, and it's the only Apple product I've ever owned. My XR is pretty old, but with an 8+ you have me beat by 1 generation - I believe there never was an iPhone 9.