I’ve had monovision from LASIK for the past 28 years, and have been very satisfied.
Now a cataract in my near-vision eye is worsening and requires surgery. My ophthalmologist is recommending a monofocal lens at plano, which presumably means I will need reading glasses. She is advising against a multifocal or extended focal depth lens. My distance eye has a cataract too, but much less advanced, so I may need surgery on that eye in a year, or in 10 years, depending on how the cataract progresses.
My question: Is there a reason to target plano on the eye I have long used for near vision? I hate to lose my monovision, and targeting -1.00 D or -1.50 D seems like it could work well for me, but I don’t want to do something that would risk bad vision in the future.
Any advice would be appreciated.
The negative I can see is if you keep the eye that has been for near that way, as the cataract in the distance eye progresses, you may find lack of good distance vision a problem for some period until you can get that distance eye operated on too. I think I'd still do it figuring a contact or glasses for the operated eye could get me past that period if necessary, but what would work for you depends on your needs.
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Both my eyes need surgery, and indecision over these kind of questions have had me procrastinating for more than a year. Good luck deciding what will work best for you.
Mini-monovision is a good strategy for eyes that have had Lasik. When you use standard monofocals you have the least risk of adverse optical effects. In your case with long experience using monovision, it makes perfect sense to target the same eye as you are used to for near vision. I would suggest B+L enVista as they are a little more tolerant of less than perfect eyes, but Clareon monofocals should work fine too. My suggestion would be to target -1.50 D in the near eye. IOLs have no accommodation effect and you need a touch more myopia to get the same close vision. I have -1.60 D in my near eye and I am quite happy with the results. I have readers but seldom use them. I also have progressive prescription glasses but almost never use those. You never back yourself into a corner with monofocal monovision. The effect can always be corrected or modified with prescription glasses.
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I agree with the surgeon's suggestion to avoid MF or EDOF lenses, but there is no reason not to do mini-monovision with monofocal lenses. The biggest risk would be that you are not ok with monovision, but you obviously have crossed that bridge a long time ago, and know exactly what you are getting.
Which is your dominant eye? I am not sure that matters, but if your current distance eye is your dominant eye, more people would feel good about keeping your current distance eye as your distance eye.
And if you were doing that, I would target about -1.50 D in the near eye.
What is your cyl (astigmatism)??
Also, are you near enough to a place that provides RxLAL?
It is controversial whether one should do distance with the dominant eye, or close with it. Some studies have found crossed monovision works as well or perhaps better than dominant eye distance monovision. I have crossed monovision. But, in this case with monovision being used for 28 years, I would say experience trumps theory, and I would stick with what has worked well for this long length of time. The brain will be used to it.
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It is standard practice to use spherical equivalent which includes astigmatism when setting targets. It would be a mistake to only base it on sphere, and to ignore the astigmatism effect.
It is standard practice to use spherical equivalent which includes astigmatism when setting targets. It would be a mistake to only base it on sphere, and to ignore the astigmatism effect.
For me, the target for astigmatism should be zero, or as close as you can get. If you were to say that you are going to have 0.75 cyl, and did not want to opt for something to correct that, THEN you could use the spherical equiv as a target.
So IMO, the question about cyl for phil09 would point different potential choices if the astigmatism was 0.5D, 2.5 D or 5.0d.
In choosing which lens, the sph number does not usually make much difference in what lens a patient would choose. Most lenses come in a wide range of sph.
My tendency would be to get at least one eye done with RxLAL, but there are things that would prevent that. One would be location. One would be budget. One would be too much astigmatism... In some cases, such as 0.5D cyl and budget considerations combined might make RxLAL less attractive.
I sort of follow your logic, but normally with standard monofocals less than 0.75 D cylinder does not justify a toric, and more to the point, a toric in those lower powers are not available. And when you go into the toric range and spring for the extra cost, you are most likely going to have residual astigmatism anyway. The steps in toric powers are quite large. For that reason one should always consider the combined spherical equivalent including the residual cylinder.
I don't know about a dominant eye. Is dominance meaningful, when the two eyes are largely viewing different distances? I would agree with RonAKA that if my near and distance eyes have worked fine for 28 years, it seems likely they would continue to work well after cataract surgery without switching the eyes for near/distance.
Cylinder was -0.50 at the most recent measurement (for eyeglasses) 11 months ago. I live in a megalopolis, so I figure I am near enough to pretty much everything.
Thanks everyone for the input, much appreciated!
I had a second opinion today, and the new ophthalmologist said, sure no problem aiming for some near vision in my first cataract eye, and continuing to rely on my good eye for distance. He recommends -2.50 D, or possibly as little as -2.00 D for monovision - he got -1.25 D monovision with his own LASIK, and regrets not having gone for a higher degree of nearsightedness.
The new doc is recommending the Alcon Clareon monofocal lens. Actually, he was refreshingly honest and said that his entire practice uses that lens, because that's the one they have a big contract for.
I'll be thinking about lenses and trying to guess what refraction might be best for me, and will plan to have my surgery in a few months. Thanks again.
I think you have taken a couple of steps up and one back with the new ophthalmologist. Monovision is good, and the Clareon lens is good too. I have one. However, I would caution you on going for -2.5 D or even -2.0 D in the near eye. That is too much if you plan to target plano (-0.25 D target) with the distance eye. I am curious. How much myopia and differential between the eyes have you had with the Lasik correction?
I'm curious about that too!
I am currently +.025 in my good eye and -6.00 in the bad eye, but that is much worsened by the recent cataract. I am trying to find some record from before the cataract, but no luck yet. I do have an old pair of glasses - perhaps I can get the lenses analyzed by an optometrist; that prescription would probably be a good estimate of my refractive state during the 25 years before the cataract.
Yes, if you have been seeing an optometrist on a regular basis they should have records of your refraction over the years. You would want to go back prior to cataracts as they can change refraction significantly. And a cooperative optometrist or optical dispensary should be able to accurately read the prescription from some old glasses too.
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Simulating monovision with contacts is another option if you are seeing well enough with a contact correction to properly evaluate the vision.
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In a post below which will be delayed for moderation, I will include a couple of graphs from a study which was done to determine the ideal amount of myopia in the near eye for monovision. Will not show up until tomorrow...
The problem with going to higher levels of myopia like -2.5 in the near eye, which is full monovision, is that you can get a disorienting effect from the differential between the eyes, anisometropia. For that reason one should not go significantly above a 1.5 D differential. The other issue is that the more myopia you go for with the near eye, the lower the visual acuity at intermediate distances, with a loss in depth perception or binocular vision. See this figure which graphs visual acuity vs distance with varying amounts of anisometropia. As you can see the -2.0 D curve shows a significant dip at 0.7 meters or about 2 feet. A 2.5 D is not shown but it would be even worse.
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The following bar graph shows the loss in binocular vision for the various amounts of anisometropia. There is some loss at 1.5 D but significantly more at 2.0 D. Again 2.5 D would be worse still. The conclusion of this study was that 1.5 D was the optimum amount of anisometropia for monovision.
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Thanks, I will keep looking into it. Problem is, I practically never saw an optometrist, because my eyes were fine for 25+ years. I only got glasses about once every 10 years, just cuz I had a vision benefit. Never wore them. Those were the good old days!
I would try the contact lens, but I'm afraid it would be hard for me to evaluate the monovision at this point, now that I am accustomed to -6.00 D. My current vision actually doesn't bother me much - I can still read fine print with either eye, even though I'm in my mid 60s, and I still never wear glasses. Unfortunately, it will continue to worsen...
The monovision setting question makes me want to consider the RxLAL adjustable lense that trilemma suggested above - the ability to fine-tune vision and monovision after insertion sounds awesome, though no doubt there may be some drawbacks, too.
Thank you, RonAKA, this is very helpful getting me started, and I will plan to do some more research.
One question: in the first chart you posted, why are they studying CDVA? Isn't uncorrected vision the relevant measurement? Perhaps I'm not understanding the terms used in the study.
If your corrected vision is still good in the -6.0 D eye, the contact lens simulation would be of value. You would want to correct it down to -1.5 D for the simulation. You could correct the other eye to plano, but +0.25 is a very small error and you likely would not notice it. You could also try the -2.5 and -2.0 D options recommended by the surgeon. If you can tolerate the -6.0 D then you may be able to tolerate the full monovision. It has fallen out of favour because most cannot tolerate that much anisometropia.
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This disadvantages of LAL is the cost which is significant due to the numerous office visits required to adjust the lens, and also the need to wear UV protective glasses to keep the lens safe from natural UV until the final setting is achieved and the correction made permanent. If the service is not available locally there would also be the travel costs.
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Unfortunately the details of that study has been taken down, and only the graphs with a bit of an explanation under each one is left. All I can think of is that they are considering the IOL correction as corrected vision. There is no doubt that the curves they present are uncorrected (in the normal sense) vision defocus curves for each target for the lenses. If you google this you should find what remains of the publication with the rest of the figures and tables.
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Semantic Scholar Optimal amount of anisometropia for pseudophakic monovision. Ken Hayashi, Motoaki Yoshida, +1 author H. Hayashi Published 1 May 2011 Medicine Journal of refractive surgery
Thanks, RonAKA, I really appreciate your help!
Vision is important, so I'm not going to worry about cost or extra visits if the RxLAL lens turns out to be best for me. I see it is pretty pricey, what with the cost of the lens and the extra work by the optometrist. But if it works well in the long run, worth every penny.
Others here who have done or investigated LAL will be able to give you a better idea, but I think you are looking at something north of $10,000 US for LAL. It probably has the least risk in hitting the targets for each eye more exactly.
What is your astigmatism (cyl) of your prescription in each eye? I think the max that RxLAL is rated for is 3D. Used to be 2D.
One of the big advantages or RaLAL is that the astigmatism is added after implant, so the axis does not have to be dealt with at the time of implant.
As I said just above, -0.50 D in the cataract eye. -1.25 D in the good eye.