The Pros and Cons of Mini Monovision

I agree that the LAL is a good solution, but very expensive and time consuming especially if one has to travel to find a surgeon that does it. It is still basically not available except perhaps for one or two clinics in Canada. And at the end of the day you still have a monofocal lens.

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It is true that a monovision trial with contats can give a slightly optimistic "view" of near focus due to even older people still having some accommodation in their natural lens. This is why I advocate doing the distance eye first. Then once you have one IOL eye you can use inexpensive OTC reading glasses to simulate various degrees of myopia in the IOL corrected eye, while checking your vision with a Jaeger test sheet. When I did contact lens tests I found I could get away with -1.25 D in my near eye. However, when I did the reading glasses test with my distance corrected IOL eye, I found I needed -1.50 D.

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I think both the contact lens simulation and the OTC reading glasses test are both worth doing if you can. The contact lens test lets you determine if you are OK with the anisometropia between the eyes, and the reading glasses test is a final check on how much myopia you want.

All great points, Ron. Thanks for all the info on mini-monovision.

I would just add that degree of loss of presbyopia caused accommodation varies a lot by person and age, so what for you was only slightly optimistic at 0.25D difference between the contact experiment and reading glasses with your distance eye, for me was >=0.75D difference (0.75D via contact experiment vs 1.5D via reading glasses on distance eye, and a bit more on actual reading IOL (still lost 2-4" close reading range compared to reading glass experiment)).

Therefore, I'd recommend using the contact simulation (instead or in addition) to determine maximum comfortably tolerable diopter difference (max degree of comfortable/tolerable monovision) and reading glass on distance post-operative eye experiment to determine minimum. Then pick something between the two for IOL surgical target for near eye, leaving a margin for actual vs target variance. The larger the range between minimum needed and maximum tolerated (minus target variance estimates), the more choice on what to target within the range.

Agree that age impacts the amount of accommodation. I was about 72 when I did my testing, and was surprised that I had any at all. I have been presbyopic since about age 45.

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Not sure that picking a power for the near eye has to be that complicated. I personally would not consider any compromise to the distance eye, and would target -0.25 D. And then I would choose just enough myopia in the close eye to get my desired reading vision without going over a 1.5 D differential. With plano distance that would be -1.50 D, and if one hits the safety target of -0.25 in the distance eye, then -1.75 max in the close eye.

Ron,

The reason I am recommending the complexity of using contact lens experiment in near eye to test max difference in near eye (probably not exceeding 1.5D difference from post operative distance eye for reasons you've articulated) and reading glass perscriptions to test minimum reading power in post operative distance eye is two fold:

1. Due to targeting error, need some margin, especially with basic monovision lens instead of LAL.
2. To allow margin for eyes to change during the rest of the patient's life post cataract surgery and retain good reading vision.

   If the patient is lucky enough to have a meaningful range (at least 0.5D) between min and max, then targeting somewhere between min and max rather than right at either end of the range protects against both above factors.

By the way, I did use RxSight LAL and glad I did, because I ended up with nearly 1 more diopter of reading monovision than either my surgeon or I anticipated to get decent near reading (at least in fairly bright light) without needing reading glasses or compromising stereoscopic vision. In my case, it happened because we'd based the near eye target on a contact monovision experiment, not realizing I still had 0.75D of accommodation in my near eye natural lens. Had we used your reading glass test (above) to test what was needed, we would have had a more accurate target. However, I wouldn't have known how much monovision I could tolerate due to not testing max tolerance using the contact experiment. My surgeon (incorrectly) did not believe I could tolerate 1.5D of monovision because he could not tolerate more than 0.75D. I'm not sure he would have agreed to target 1.5D of mini-monovision in a fixed focus lens, due to concern I may not tolerate it. But his situation is different needing extremely precise depth perception and near distances to conduct surgery and possibly diffences in our visual processing in our brain, as I tolerated a many diopter difference between my eyes for a year having done one surgery a year before the other (I used a contact lens in the pre-operative eye some of the time to keep the eyes vision closer together).

LAL is more readily available in the States, where I reside. I only needed drive 1/2 hour to get to all appointments. You are correct that it is more expensive, still results in monofocal lenses, and requires a lot more time (typically 3-5 extra appointments per eye for the light adjustments and lockins) and wearing special UV protective glasses for several weeks for each eye. So definitely not for everyone. But it got me substantially reduced dependence on reading glasses compared to what would have happened had we used fixed (non-LAL) monofocal lenses with the information we had pre-surgically.

Thanks to all the mini-monovision information you provided as it helped me determine the optimal max for my mini-monovision (1.5D-1.75D difference), which is working as a good balance for me (great distance vision, depth perception, night driving, with decent reading and intermediate vision).

Interestingly I viewed a Mayo Clinic video on their LAL experience thanks to another contributor here giving it to me. They showed that the large majority of their LAL patients settled on -1.3 to -1.5 D for myopia in the near eye. I will will post a link in a subsequent post, as I think it will go into moderation... It has a lot of good information on the LAL.

Here is the link.

https://medprofvideos.mayoclinic.org/videos/light-adjustable-lens-what-every-ophthalmologist-should-know-webinar

Hi JDvision,

Thank you for sharing your LAL journey. I believe you have the LAL in both eyes. Will you share what your eye refractions are? I have to ask: did you receive EDoF in your near eye? This has been a huge question for me. My near and intermediate vision is the most important to me and I am willing to wear glasses for driving and watching TV. The near vision quality (sharpness and contrast sensitivity) is important to me.

Thank you for any help!

Hi Julie,

Yes I had LAL in both eyes. I do have EDoF in my near eye - not noticeable in my far eye even though both were significantly adjusted towards reading (the direction that adds EDoF). I have good vision from around 18" (16" in bright light) to several feet in my near eye. This was a result of pushing from just past plano in my near eye (I believe it started at +0.25D) out to -1.75D with +0.25D cylinder (the minor astigmatism appeared on a 4th adjustment after correcting to 0 after 2 adjustments, as each time, my sphere adjustment only went about half way to the target). My distance eye is near plano (-0.25D sph +0.25D cyl). With astigmatism equivalence factored in, it works out to exactly 1.5D difference between eyes.

You may want to target both eyes for near instead of trying for mini-monovision as you would get best near and intermediate if your eyes could work together to improve visual acuity in those ranges (you lose most of that benefit at mini-monovision ranges for the benefit of better total DoF), or you might be able to target near at -2.5D or nearly whatever your actual reading offset is (hard to precisely test if you still have any accommodation in your natural lens as you lose that with the LAL and most other IOLs) for near and up to 1.5D towards distance relative to that for your distant eye (not necessarily plano). I think a good opthamologist or optometrist can give you a numbing eye drop which immobilized accomodation to do a more accurate preoperative test assuming your cataracts aren't so bad as to substantially interfere with the refraction. I have no idea if this type of mini-monovision can work OK as that is not normal for mini-monovision (always plano target for distance eye as far as I know). It is possible that the brain can only pick the best diatance image if it is close to plano, so that option would require more research. I know I was not at all happy with a contact lens in my distance eye that made my distance vision less clear. Surgeon usually targets 1D towards distance and pulls it in with adjustments to achieve some EdoF. I got more than 1D because I originally only planned on 0.75D of near offset and went for 1.5D as I tolerate it well and was not happy with my near vision at the lower offset.

In your situation, I believe the tricky part will be figuring out exactly what to target for near (surgically, and then adjusted to your preference) as per Ron, best way to get accurate reading is to do distance eye at plano first and once done, test with reading glasses what you need for reading power.

Thanks Ron. Great video. Encouraging to see I'm right in the common range for selecting mini-monovision with the LAL. In my location, I don't think mini-monovision is as popular, or at least if done, done at much lower differences (some call it micro-monovision) as I didn't run into anyone else when waiting for all my adjustments and lockins who said they were getting mini-monovision, and I talked to a few. Also, as I said, the surgeon was wary of more than 0.75D of difference based on his own experience.

For mini-monovision, I aim for the IOL power difference between the eyes to be no more than 0.75D. I target the dominant eye for emmetropia and the nondominant eye between -0.5D and -0.75D, with power adjustment made to the nondominant eye based on the result of the dominant eye. To date, we've had little trouble with patient adaptation due likely to the small interocular diopteric difference. A greater difference between the eyes may lead to contrast sensitivity, stereopsis and binocular visual acuity issues. Cynthia Matossian, MD

Mini-monovision allows a maximum of –0.75 D anisometropia, or between –0.25 and –0.75 D. “Conventional monovision aims for far and near vision, while with mini-monovision, the focus is on intermediate vision ,” Dr. Assia said.

I suspect the surgeon has influence over patients, and steers them to micro-monovision. I believe in doing the testing yourself and deciding what you like personally.

I can't say I agree with the opinion stated by Cynthia Matossian. I wonder if she actually has done it with her own eyes?

She's a cataract surgeon. Not sure if she is old enough for cataracts!

Exactly. Tells others what to do, but has not done it herself!

You may want to target both eyes for near instead of trying for mini-monovision as you would get best near and intermediate if your eyes could work together to improve visual acuity in those ranges (you lose most of that benefit at mini-monovision ranges for the benefit of better total DoF).

I just been wondering about this very question and it was so helpful to read your post addressing this issue. Just to confirm, does DoF refer to depth of field? Also, would you anticipate that the benefit to visual acuity when setting both eyes to near might slightly improve the blurriness I experience outside the -2.0 range?

Many thanks!

Thank you so much JDvision!

I think I understand RonAKA's and your suggestion. Target one eye for distance using the LAL. Use glasses to ascertain what my comfortable near vision is in this LAL distance eye. Then I will know what my target should be for my near eye.

Yes, by DoF, I meant Depth of Field (term often used in photography) or Depth of Focus (same meaning but I've heard it referred to more this way in optometry). I meant in combination with both eyes (one for distance, and the other for intermediate and as much near as you can get without exceeding ~1.5D difference or whatever max difference you personally find comfortable).

Not quite sure what you meant by "outside the -2.0 range" (not sure if you meant near or intermediate). Having the two eyes with similar focal length (e.g. both near plano or both set for near vision or intermediate vision) results in binocular summation of visual accuity, meaning sharper vision with both eyes than with either one by itself (for instance, reading one line of smaller print lines at the tested distance). In mini-monovision (by which, I mean between between 1D and 1.5D of difference, as definitions vary, and I would call 0.75D or less micro-monovision), the summation effect may not exist at all or is reduced, but your brain generally picks whichever image is sharper from either eye to show you. The summation effect if active when both eyes have similar focal depth should work within the focus range, but I'm not sure how it drops off as you move outside the focus range, especially as I have mini-monovision. That said, the LAL lens can provide some additional EDoF (E stands for Extended) if surgical target is more distant and adjustments pull it closer towards reading distances. I have a few feet of DoF in my near eye as my near eye was adjusted nearer by almost 2.0D from its starting point. Degree of EDoF is likely dependent on magnitude of nearer adjustment performed. But you don't want surgical target too far off from what you think your final target will be as you risk not making it to your target if starting too far. My surgeon targeted about 1D of near adjustment to presumed final target vision, I believe. I ended up needing 4 adjustments (advertised max is 3, after which asjustment effectiveness can drop off as fewer macromers remain movable for adjustments) to get to my updated desired target in my near eye.

Julie,

Correct, if you decide on mini-monovision vs optimizing near/intermediate over larger range.

But I would also recommend trying the temporary contact lens experiment to determine how much difference you can tolerate and pick something between the min and max if you have sufficient range to do so.

I found even the reading glass in post operative distance eye experiment didn't fully capture optics for my near eye. I see better in my distance eye with 1.5D reading glasses than I do in my near eye with ~1.5D (LAL LDD) near adjustment with no glasses.

Thanks JDvision!

By "outside the -2.0 range" I was referring to my new lens because my one week post op refraction shows the sphere at -2.0D, cylinder at +0.25. Other notations include Axis 125, Dist VA 20/20-1, Add +2.5, Near VA 20/20. The target was -1.50D and my goal was near/intermediate wearing glasses for far distance. My disappointment is that I'll need glasses for near distance as well but I realize with eyes, it could be much worse.

I have no experience with monovision and my remaining cataract plus considerable myopia make a contact lens trial unpromising. My crisp vision extends from 2-3 feet. I would only consider mini-monovision with a maximum difference between my eyes of .75D. I recognize that targets are not guaranteed.

I'm asking questions to help me in deciding how to proceed with this new information. My goal is to maximize visual acuity while minimizing risk.

It sounds like you have an excellent team of ophthalmologists and surgeons for your LALs. If I could find a great LAL practice I might consider it but even asking my ophthalmologist and primary care physician, I received one name but no recommendation.

Thanks again for all the information you've provided!

JDvision,

My cataracts are too advanced and will not allow me to use contacts to trial Mini monovision. I really appreciated you helping with the suggestion of using glasses.

In your near eye , are you able see better if you use glasses? Will glasses make your vision sharper? How is your contrast sensitivity in your near eye? Did I understand correctly that you're near eye received a 2 D adjustment? But how do you know the amount of EDoF?

With the LAL, If my surgical Target is +0.25 and the first adjustment takes me to -1.25, does this mean I have received a 1.5 D adjustment but won't know how much EDoF?

This is hard stuff to understand!

Judith, if I understand you correctly, you have had cataract surgery on one eye with a monofocal IOL ending up with -2.0D sphere and +0.25 cyl. That is equivalent to -1.875D net (average across your eye as part is -2.0D and other part is -1.75D due to very minor astigmatism. Your goal is no glasses dependence for near and intermediate and OK with glasses dependence for distance. Is that correct?

It is odd that your prescription claims 20/20 for both distance (-1) and near when you say you only see clearly 2-3 feet as that is neither near (14" is standard for near, I think) nor far (20' for standard distance test). I think the -1 means you missed one letter for distance Visual Accuity test (I'm not familiar with that notation, so not sure), which means you were very close to testing 20/20. Maybe your own experience is in dimmer light than the exam room, as dilated pupils due to dim light will cause reduction in DoF (loss of "pinhole effect"). If so, you can reduce reading glass dependence in bright light.

In any case, if my understanding of your above situation is correct, you should be able to improve your near vision with careful selection of your remaining IOL power for your second cataract surgery. Try different strength reading glass prescriptions (once your post operative eye has fully healed so your vision should be stable) to determine how much remaining correction is required to get good near and intermediate vision. Per your prescription, it should only be around 0.5D as your prescription claims +2.5D for reading and you already have 2.0D. Finding a +0.5D reading glass off the shelf is unlikely, but any optician should have a +0.5D lens (and others in 0.25D increments) to try and you should easily be able to find an off the shelf 1.0D and a 1.25D to try. Remember that unless you got an accomodative IOL (most are not), you will have lost any focal length adjustment in your post operative eye (your eye muscles can no longer shape your lens to change its power). You'd want to know the smallest reading power needed to get clear vision, and may with eye doctor (optician, optometrist, opthamologist, eye surgeon) assistance, still be able to try a contact lens experiment to test the planned power for your pre-operative eye to make sure you tolerate it well. If your cataract substantially interferes with your vision, that won't work, but myopia shouldn't be a problem, as the lens is set to plano minus the power you are testing (the temporary contact lens could take care of the myopia). It would be good to also test how you do plus and minus 0.5D from whatever you target for your second eye as your first eye was 0.5D off from target. But if you get close to target, you could improve your near vision to hopefully cover closer than 2 feet, and then you might get from near to 3 feet sharp with both eyes and need glasses only for distance.

As to finding an LAL provider in your area, you could try contacting RxSight directly and ask them for a list of providers in your area. Not likely to be many, but at least it would tell you choices to investigate reviews and recommendations from. Advantage of the LAL in your situation is more precise targeting correction post operatively and ability to test different power levels before lockin. Also, some EDoF if adjustment is in the near direction. Disadvantage is added cost, a bunch more post operative appointments and having to wear the protective glasses until 24 hours after final lockin.

Thanks so much JDvision!

Yes, that is correct but the issue of distance is more nuanced. When I read about distance, examples often include driving and all outside activities. I now consider these conditions far distance. I'm fine with wearing glasses for far distance.

I've come to understand that in my case distance vision is also required for good or even fair vision beyond 5 to 8' when indoors. I consider these conditions near distance. In other words, my vision is too blurry for comfort outside the range of near and intermediate vision and I look forward to wearing progressives.

I have a terrible time with the vision tests for far vision. In this case, it is a matter of reading letters in increasingly small fonts. I feel like I can barely see a thing and spend most of the time guessing. I think you can get several letters wrong and still receive full credit. By the way, the conditions in the testing room are very dim.

I can see well reading small print both at home and when tested in the clinic for near vision. Is this because my operated eye is set for 2.0D? Would it even be possible for me to have 20/20 vision in that eye?

What sharpens my vision quite a bit is looking through the pin hole occluder but I don't remember if I used that with both eyes or only one. If only one, I don't remember whether it was my operated or unoperated eye.

I just did a quick Google search and found the following:

A pinhole occluder (an opaque disc with one or more small holes) is used to determine whether reduced vision is caused by refractive error. If this is the case, the pinhole will cause an improvement in visual acuity.

Do you know if the target being missed by .5D would account for this level of refractive error?

Thanks again!

Julie,

Yes, I am able to see better (very well actually) near with reading glasses. I now (sometimes) use weaker reading glasses than before my near eye surgery and adjustments (and sometimes no reading glasses and never distance glasses). The advantage of monofocal (LDD or otherwise) IOLs is that any refraction issues are fully correctable with glasses/contacts vs multifocal or EDoF lenses which can have uncorrectable light artifacts.

Ron first suggested the reading glass experiment on post surgical eye. I seconded it, so I can't take credit for that idea. Thanks Ron.

I have good contrast sensitivity in both eyes as far as I can tell. Hasn't been tested at least since adjustments, but I don't notice any issues at all.

Yes, net 2D adjustment in my near eye. I'm guessing on degree of EDoF from adjustment simply based on being able to see well from 18" to a few feet. LDD is supposed to create EDoF when corrected towards near direction and my assumption is that the effect is somewhat proportionate to the degree of adjustment towards near vision but I don't have a direct measure of degree of EDoF.

Your analysis was mostly correct - net adjustment would be the difference from post surgical refraction (not necessarily surgical target in case target and post surgical refraction differ) to the final refraction before lockin. Apparently the first lockin results in a minor refractive change canceled out by the second lockin. Degree of EDoF achieved is not known in advance but presumably highest with larger adjustments towards reading/near. Surgeons plan for that by setting surgical target based on your final desired target to plan on some (usually 1D I think) adjustment towards near.

My thoughts, absent from using the LALs of course, is that there is no simple way of measuring the EDOF gained. I found the Mayo clinic guy's comments interesting. When asked about the EDOF claims for the LAL, he said something like that is an interesting topic, the outcomes were not part of the FDA approval, and we are still learning. I translate that to mean, they really don't know how much EDOF is gained.

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If I was getting the LALs I think I would treat the EDOF gained as a bonus, and not something to go to the bank with. And, one has to keep in mind that using spherical aberration to increase EDOF has a price in clarity and visual acuity.

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I think I would target -1.0 to -1.25 with the IOL power calculation formula, and then increase myopia from what I got to -1.50 D in the near eye. In the distance eye, I would target +0.50 to +0.25 D and then adjust back to 0.0 D. At the same time one wants to adjust Cylinder to 0.0 at each adjustment.

I can see well reading small print both at home and when tested in the clinic for near vision. Is this because my operated eye is set for 2.0D? Would it even be possible for me to have 20/20 vision in that eye?

According to the refraction you quoted, you were tested at 20/20 for near vision already, and you said above that you can see well reading. Certainly, with +2.0D, you could be seeing 20/20 near, and your refraction suggests +2.5D would be ideal for near reading for you which is only off by 0.5D.

While they may give you credit for a line if you got most letters right on the line, if you got most wrong it should be quoted as the line above "plus". I think you are supposed to get at least half right for them to give credit for the line. Maybe you would be better off not guessing quite so much if you think they're overly optimistic in visual acuity results.

The reason I brought up pinhole effect is that with bright light, your pupils will contract and that will naturally increase your DoF, even with a non-accomodating IOL implant. So you can see if your vision at different distances improves with bright lighting.

0.5D refractive error from target in your case was towards near, which should increase your near vision at the expense of intermediate and/or what you called near distance. The best way to test how much difference a particular correction would make is testing a lens with that power in an optician's office (at least for distances within the size of the exam room). Stronger reading prescriptions can be tested with off the shelf reading glasses, but testing for more distance correction requires lenses which are not available outside an optician/optometrist office.

You likely could gain near distance and some far distance visual accuity by targeting your second eye closer to plano (0D). You'd need to test different prescription values at the eye doctor to figure out what target works best for you for different distances. You could do a monovision contact lens temporary experiment to test how much difference you comfortably tolerate before committing to an IOL power. But keep in mind you'll lose whatever accomodative you have left in your natural lens (unless you're getting an acxomdatice IOL).

One caution, though. The general rule is to have the distance eye be the dominant eye, so you should check which eye is dominant. To do that, you form a triangular window with your thumbs and index fingers of both hands, stretch your arms to max length and look through that window at something distant and close one eye at a time to figure out which eye sees the object stay within the window formed by your hands. The one still seeing the object is your dominant eye. If that is your pre operative (presumed distance) eye, then this would be normal mini-monovision. If not, you'd be getting crossed monovision, which is less common. However, I just searched and found a study indicating similar patient satisfaction whether crossed or not.

LAL might give you some extended DoF.

i generally agree with Ron's comments on EDoF for LAL, except if you are using LALs, I would target for -1.0D of adjustment (set the IOL surgical target +1.0D further than the planned final target to opportunistically leave room for any EDoF you can get) rather than 0.25D to 0.5D.

Also, while spherical abberation theoretically reduces clarity and visual accuity, in practice, the LAL has a range of 2D of spherical adustment and 2D of cylinder in either direction without meaningfully affecting optics, so I wouldn't worry about that at all.

I had almost the full 2.0D of spherical adjustment in my near eye with no noticeable abberation effects and what appears to be good DoF.

Thanks JDvision!

The best way to test how much difference a particular correction would make is testing a lens with that power in an optician's office (at least for distances within the size of the exam room).

My surgeon suggested plano but I have no experience with monovision. My first priority is to be comfortable and avoid risk. I realize now how easily the target can be missed and would like to avoid a final result which would be exhausting due to too much difference between my eyes. With that in mind, I would feel more comfortable with a target of either -1.0D or -1.25D or even -1.50D.

My surgeon gave me a 1.0 and plano lens to try. In the office setting, the 1.0 lens made a great improvement in my near distance vision, but again I'm not sure if this guarantees I'd be able to tolerate the difference between my eyes.

To confirm your suggestion about testing lens power in an optician's office, does that mean I could drop by where glasses are sold and ask to look through lenses from -1.50D through -1.0D?

Considering that my operated eye is set to -2.0, do you know if any of these settings fall within the average difference between eyes in the general population? In other words, do you have a sense of the difference between healthy eyes in the general population?

My unoperated right eye is dominant using the test you describe.

So many questions! Many thanks for your help.

My thoughts were that if one does not go overboard with excessive room for adjustment then there will be more macromers left for additional adjustments if needed. Also, one of the downsides of the LAL is the amount of chair time and trips to the clinic required to make the adjustments. If you start closer to the final target then that reduces chair time and travel time. On the EDOF I think that there is no great need for any in a plano/-1.5 D mini-monovision configuration. Hitting the targets (or your personal preferences) is more important than anything the EDOF could add. Hitting the targets is where the LAL has a big advantage over a standard monofocal.

Judith, when you said 1.0, I'm not sure whether you meant +1.0 relative to plano for your pre-operative eye (which should leave a 1.0D difference between your eyes and reduced visual accuity at far distance) or something else. It presumably wouldn't likely be a 1.0 power lens if your pre-op eye is not currently plano.

I may have misspoke when I said optician. You may need to find an optical office with an optometrist who can create temporary glasses by placing individual lenses in their temporary frames, as minus diopter glasses are generally only made to prescription. With your near eye having been done first, Ron's experiment based on reading glasses wouldn't work, so we have to improvise. You could try calling around optical centers to see if any carry -1.0D to -1.5D glasses in house that you could try on to see the focus change in your post operative eye.

Once you have some idea of strengths you may want to try, you could ask an optometrist to get you temporary (disposable, soft?) contact lens for your distance eye to give a longer trial period. Your surgeon's office may be able to coordinate that for you or you may need to do it separately and bring the information back to the surgeon. Note that a reliable refraction for your pre-op eye is needed to do that as the prescription would be need to a modification of getting your eye to plano. Just keep in mind you may still have some accomodation in your pre-op eye so you may need on the stronger end of what works for you depending on level of remaining accomodation. That's why the eyeglass test in post-op eye is more accurate for determining visual accuity (no accomodation from the IOL).

According to the Cleveland Clinic: "Anisometropia is a relatively common condition and is estimated to affect up to 28% of people."

That said, it is serious in children as it can cause lazy eye if not corrected, but in adults, since the brain is already developed, it is more a function of what each person tolerates well. Induced monovision is commonly used in presbyopic Lasik patients. Common monovision thresholds for tolerance discussed are ⇐0.75D or ⇐1.5D differences. The contact lenses test should be able to give you some idea of your own tolerance (though natural accomodation may still affect it).

If I were you, I would test (with glasses and contacts) to see if 1.5D difference (-0.5D post op target in distance eye) worked for you to see all ranges sufficiently as well as 0.75D, -1D, and -1.25D difference) If either of those worked for you, pick something mid-range in what worked, as they would be a good compromise for larger range or focus but keeping difference between eyes from being too much.

You may be a great candidate for LAL in your distance eye as it could increase confidence in more precise achievement of post operative target and let you try a few possibilities for several days post op before lockin. Note that LAL is indicated to correct at least 0.75D of corneal astigmatism (not necessarily what you see now as lenticular astigmatism can sometimes cancel some corneal aatigmatism). If not using an IOL that treats corneal astigmatism if you have any, it could be treated surgically at time of cataract surgery. Not all cataract surgeons offer the LAL as it requires a special post surgical followup for adjustments and lockin and a special Light Delivery Device to perform the followups.

Ron, As someone who paid for and got the LAL, I see the advantages as:

1. Hitting final target more precisely
2. Ability to test different prescriptions in eyes under final conditions (no cataract and no remaining accomodation) before committing. Especially helpful for mini-monovision induced anisometropia testing.
3. Opportunistic EDoF without the risk of light artifacts, such as from EDoF lenses

Whether #1 or #2 is more important to a patient depends on circumstances which may influence how close to target to start. If #2 is more important, I'd start closer to target (say +0.5D from target as you suggested) for reasons you said. If #1 is primary concern, I think starting +1.0D from target makes a lot of sense because with LAL specified to provide up to 2D of sphere and 2D of astigmatism correction, risk of missing target starting at +1D from target (even accounting for target error) is low. I got 4 adjustments and I heard some have even done 5 or 6 though by then macromers left may limit power changes. The only reason I pushed the limits to 2D adjustment is because I post surgically decided to go for an extra -0.75D of reading correction beyond initial post surgical target, and the actual post surgical refraction was 0.25D in the wrong direction, and I was still able to achieve my updated goal.

#3 is still of some value, so it makes sense to get this if not compromising the other priorities. In any case, my eye surgeon who has implanted several hundred LALs and is presumably well trained by the manufacturer and more expert on it than either of us, picked about +1D, so his thinking presumably matches above.

As to chair time and trips to the clinic, I put that in comparison with living with this prescription for the rest of my life. I'd rather spend extra time now to maximize benefit (gain opportunistic EDoF) than wonder later if I could have done better. For some, the appointment schedule might be difficult and could be a bigger issue for them, but for me, that was not a factor.

I remain somewhat skeptical of the EDOF benefits as there have been no clinical trials or FDA approval of that aspect of the lens, at least based on the Mayo Clinic video. With lenses like the Vivity only gaining 0.6 D EDOF with a lens specifically designed to do it, I would be extremely skeptical of any claims of a 1.0 D gain just due to side effects from a myopic power adjustment. And to achieve 0.6 D, the Vivity does sacrifice peak visual acuity and a significant loss in contrast sensitivity. There seems to be nothing more than anecdotal evidence behind the LAL EDOF claims.

To clarify, I never claimed to (certainly didn't intend to) have achieved 1D of EDoF, just that I believe whatever EDoF effect exists, it is likely proportional to magnitude of myopic adjustment and that I think I got some. I wasn't sure how to quantify the EDoF I achieved, just that I had a few feet of sharp vision depth. I don't know how much DoF I would have had with no EDoF for comparison, and as you say, that is anecdotal.

A fair point that we cannot count on specific EDoF achievement unless and until RxSight submits EDoF claims the FDA evaluates and approves. EDoF would be off-label use at this point. The FDA has a good page 'Understanding Unapproved Use of Approved Drugs "Off Label"'. This us a medical device, but tradeoffs are similar. That page gives both pros and cons for doing so. Cataract surgeons regularly mention the possibility of EDoF benefits with LAL. Hopefully they do carefully, not overstating, though that will obviously vary by person.

That said, to me it was a low cost opportunistic potential bonus with negligible downside. I believe the best way to determine is what I said above - if trial prescriptions is highest priority, then follow your 0.5D adjustment targeting advise. But if top priority is final target precision based on presurgical decision and fairly high confidence on post surgical target exists, I would still follow 1D adjustment target. Ultimately, it is an individual decision between surgeon and patient.

I also just ran across a writeup of LAL posted on the The American Society of Cataract and Refractive Surgery (ASCRS) website:

https://ascrs.org/-/media/files/2021-ascrs-course-handouts/814_9863_135_2019_escrs_article-on-lal.pdf

It doesn't make any claims about EDoF for the LAL current version, but I noted with interest comments on how it helps with mini-monovision post surgical fine tuning, which matches my own experience.

Thanks JDvision,

I meant -1.0D so if that target is achieved, it would be 1 diopter difference.

I visited the surgeon's optical shop but they do not have the lenses. That said, I'm sure my optometrist can help when I have an appt next week.

I'll experiment with those variations from -1.5 to -1.0.

Thanks!

Judith, you may want to try plano as well for comparison and to help you decide which powers to try with contact lens monovision experiments. Plano would be a big difference between your two eyes in this case (2.0D), but might still result in a better experience as I'm not sure how well the brain integrates less sharp images. 2.0D difference may well be too much, but it's good data to have which ranges work well for you. You should probably ask if you can try a couple of them (say the best 2 or 3) outside the exam room also to get a better sense of a range of distances and how you feel seeing a larger field of view also. You'll want to check if any powers you are seriously considering create a blurry zone at mid distances as that wouldn't be ideal.

Thanks JDvision. Are you thinking of contacts or lenses help up to my second eye?

JDvision,

You have been kind and amazing to share your LAL experience. I have had so many

questions. One more concern: will EDoF feel natural, or will it take awhile or be "slow" to focus?

I am encouraged that glasses will make vision sharper with the light adjustable lens and the EDoF does not appear to be over done.

RonAKA,

That is an excellent plan. I have thought through this and I would target my near eye -1.25 and my distance eye +.25 and adjust just as you suggested. But THEN the thought occurred to me, if I can't tolerate mini-monovision, and decide to be near sighted in both eyes using my 2nd adjustment to move from plano to -2.5, would that create EDoF?

Ideally, the less adjustments the better. If you hit your targets, you still have to have 1 adjustment and the lock-in. I don't know if you have to have 2 lock-ins.

I think one issue you may run into is being able to go from +0.25 to -2.50 D is that is in excess of the nominal adjustment limit of 2.0 D. However if you don't need all the astigmatism correction I recall you can borrow from that 2.0 D allowance. Based on the video EDOF is created when you adjust for more myopia and it would seem some would be gained.

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I believe at present there is no further adjustments after lock in. They did talk about a new development where they hope to make the adjustment wavelength a combination of two wavelengths that are not found in nature. Then no lock in is required. Your limit for adjustments then however would be still limited by the macromers available. It appears some get used up with each adjustment.

Judith, I was recommending temporary glasses and contacts experiments to help you determine target lens power prior to your second cataract surgery.

Whether and what corrective lenses you seek post surgically will depend on what IOL powers you chose and what ranges of focal distance they cover. My only observation on post surgical corrective lenses is that you will no longer have any accomodation left (assuming the IOLs are non-accomodative, as is the case with most lenses) so any prescriptions need to be more accurate as your lens will no longer compensate for small differences. I noticed this in fitting a contact lens for my post surgical eye was more difficult than my presurgical eye (I had a year between vataract surgeries so updated contact lens perscription in between to balance my eyes and attempt to cover all distances with a bifocal and a trifocal contact).

Julie, the EDoF effect from LAL myopic adustments is mild (and mine was likely on the high end of what the LAL provides as I had 2D of myopic adjustment). No visual artifacts and no slow focus that I notice. The only delayed focus I notice is when I switch from reading glasses to no corrective lenses, my brain takes a second or two to get used to the change which can affect focus until that happens. But no delayed focus at different focal lengths that I've noticed.

any prescriptions need to be more accurate

Exactly. And this is why, especially if you're getting progressive lenses, it's a good idea to go to an independent optometrist and not get your glasses from, say, Warby Parker or Costco.

If you want to see how a commercial EDOF lens performs, google this:

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Vivity P930014 Package Insert PDF

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It is approved by FDA but comes with a warning that contrast sensitivity is compromised. You can see with Figure 4, on page 4, the degree to which contrast sensitivity is compromised compared to a standard AcrySof IQ monofocal. It is worth noting that at closer distances it crosses over to become superior to the monofocal.

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On page 13 you can find figure 5 which illustrates the small loss of visual acuity at the peak vision point, and magnitude of the EDOF at closer distances. At a logMAR of 0.3 (minimum acceptable vision point) it achieves a depth of focus extension of slightly over 0.5 D. This is the kind of test RxSight would have to do in a clinical trial to demonstrate the EDOF it actually achieves, and what the impact is on peak vision.

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Alcon's "solution" to this contrast sensitivity issue is to recommend that it be used bilaterally which apparently brings the contrast just above the minimum required by the standard. I think a much better solution is to use the monofocal in the distance eye, and only use the Vivity in the near eye. Due to the clinical data available it would be reasonable to target the Vivity in the near eye to -1.0 D to take advantage of the EDOF of 0.5 D to bring the expected outcome to achieve acceptable reading vision of -1.50 D.

The same strategy could be used with the LAL by minimizing the EDOF in the distance eye, and going for more in the near eye. The issue of course is that there is no data as to what one could reasonably expect with the various levels of adjustment. It would be a bit of a guess for a starting point. But, since the LAL is adjustable, the final myopic can be adjusted "to taste".

Needing more accurate prescriptions and Costco lenses not being good enough is certainly not my experience. Currently I know my Costco prescription progressives are off by 0.25 D Cylinder in my distance eye, because that is how much it has changed since I got them, and I have not bothered to get a new lens. I wear them so infrequently it is not worth it, and really 0.25 D is not much error.

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With respect to quality one has a couple of choices at Costco. The top quality is the Essilor Accolade Freedom 4.0. They are essentially the same as the Essilor Varilux. I would avoid Zenni though. My brother got some and they have significant error compared to what they were supposed to be.

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I use reading glasses much more often than my progressives. They are just standard OTC readers at +1.25 D power. Combined with my mini-monovision they give me -2.85 D in my near eye and about -1.65 D in my distance eye. I find they work fine for the occasional close vision task, but I sure do not like them for any kind of distance. I take them off right away after doing what I need to do. Before I got into this I thought it would be essential to get some prescription reading glasses or do a lens exchange in some OTC readers to give me -2.50 D in both eyes. I have not found that to be necessary. But, then again I am not a book reader. I do almost all of my reading off a computer monitor, and don't need glasses to do that.

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My overall experience is that having IOLs in both eyes in a mini-monovision configuration has not made me more sensitive to prescriptions errors at all.

But, then again I am not a book reader.

I won't hold it against you. 😉

Julie,

I think you might be expecting more from LAL than it can deliver. I would not plan on being able to get more than 2D total adjustment (cumulative in both directions, so for instance if you move 0.5D in one direction and then 1D in the other, that is 1.5D of total adjustment). You might get more total, as Ron mentioned if you don't use max astigmatism range, you may get more sphere, but I wouldn't count on it. You will likely not be able to get 2.5D adjustment in a single adjustment if at all. I asked for a 1.5D first adjustment with the goal of trying it, and backing it down if it was too much, and the machine gave a warning that the adjustment was out of range - exceeded what one adjustment could accomplish. I only ended up with 0.75D sphere adjustment in the first adjustment (plus most of my astigmatism was eliminated in same adjustment). It took 4 total adjustments to get 2D total power adjustment. Most of my sphere adjustments moved only about 1/2 of the programmed power change, though astigmatism adjustments moved mostly to target in a single adjustment. The LDD team has seen the reverse with some other patients, so while you get some trial, it is likely not as many as you think, especially if your adjustments are large.

Given that your remaining cataract is too advanced to do the contact mini-monovision tolerance test, I would recommend surgical target should be as close as possible to your post surgical trial goal, to maximize the amount of adjustment range available to undo monovision if it doesn't work for you or to fine tune it if it does. You'd lose some potential for EDoF if you like the mini-monovision but it is likely not worth the risk of not being able to fully undo your mini-monovision LAL trial since your confidence in tolerating it is low.

You will need both lockins. When they started with only one lockin sometimes (several years ago, I think), they discovered some post lockin drift, so now 2 lockins are always required (I heard of a 3rd lockin required if dilation was insufficient for the LDD to access the entire lens (6.5mm dilation)). No adjustment possible after lockin (all remaining macromers are polymerized via lockin) with current technology. You can delay adjustment and lockin appointments by a week or even a few weeks if necessary to be confident in what adjustments you want. or only adjust one eye in an appointment even if you decide to do both eyes at once. They are supposed to delay adjustment if refraction is unstable (they usually do 2-3 refractions at each adjustment appointment to make sure adjustments are targeted correctly). Unstable refraction can occur if eyes are dry so minimizing that (with eye drops or hot compress in my case) before adjustment appointments reduces that risk.

Ron, I believe the reason you have not seen a difference is prescription accuracy sensitivity and I have is because you only had 0.25D accomodation left in your natural lens at the time you had cataract surgery, whereas I had >=0.75D of natural accomodation left. 0.25D is so low as to be hardly noticeable (some would notice and some would not), whereas 0.75D is significant enough to be noticeable and affect prescription satisfaction. I saw a big difference in fit accuracy in my pre and post operative eyes on contact lens prescription accuracy tolerance.

how did you test for accommodation?

I believe @JDvision is referring to my testing to determine what impact an IOL would have in comparison to a contact. From testing using contacts I determined that I would be OK with -1.25 D in my near eye using a Jaeger test. That however was with a natural lens/contact lens which would still have some accommodation. To get a more realistic view I then used different reading glasses with +1.25 and +1.50 D with my IOL eye set for distance. It would have no accommodation. What I found was that I needed the equivalent of +1.50 D to read the J1 line with the IOL eye, while I could get away with -1.25 D with a contact and read the J1 lines. From that I guess one could deduce that I had 0.25 D of accommodation left.

Thanks JDvision!

ah..ok that makes sense

Regarding accomodation testing, Ron, that is exactly what I meant, yes. In my case, the same test (pre surgery contact test compared to post surgery reading glass test in other eye) showed 0.75D of accomodation difference between the two (0.75D contact vs 1.5D reading). Thus I concluded that I still had 0.75D accomodation pre surgery whereas Ron only had 0.25D.

Thanks JDvision. Are you thinking of contacts or lenses help up to my second eye?

I'll try answering above again as I think I misparsed your question. I suspect you meant "held" not "help" above. Both sort of.

You can start with either loose lenses held up to your eye or have them placed in a temporary eyeglasses frame designed to hold those lenses. Optometrist offices have those along with loose lenses. If you have astigmatism to be corrected, the temporary glass frame would be easier as you'd need both an astigmatism correcting lens held at the correct axis and a sphere adjusting lens both in front of your eye.

Using the lenses (loose or in temporary glasses frame) gives you a rough idea of what experimental power you may want in a contact for your pre-surgical eye, rougly what vision that would give you and a quick check on how well you tolerate it, to experiment with mini-monovision. The temporary contact lenses give you more time to experiment than just in an optometrists office.

Lenses in front of both eyes to test for ADD power difference between distance and reading in both eyes give you an idea how much accommodation may be left in your pre-surgical eye which would be lost post surgery. That factors into target power choice to help interpret accuracy of contact lens mini-monovision experiments (to help give you an idea how much change you may see in accuity comparing a contact lens on an eye with remaining accomodation vs an IOL with the same power but no accomodation left. I suspect if you explain you want to test mini-monovision tolerance and target prescription, as well as remaining accomodation in your presurgical eye, the optometrist would know how to conduct these tests. Only if they don't would you have to ask for all this explicitly.

The key is to get as confident as you can pre-surgery on target IOL desired prescription (surgeon will convert to required IOL power based on your eye geometry and refraction). Then, if basic monovision lens, hopefully post surgical refraction is close to target. If LAL, then you have opportunity to experiment a bit post surgically and to adjust final prescription to preference.

JDvision,

I never even thought about the light adjustable lens in this way. It never occurred to me that there would be a diopter restriction. I was thinking a diopters total of 4 - you might move to myopic -2.5 diopters and not like that and then move back to something close to Plano. I was just focused on how many adjustments I could receive. I sent you a private message, I hope that is okay.

I obviously have been too focused on the vision quality with the EDoF.

Julie,

Because of the diopter adjustment limitations of the LAL, I would recommend figuring out your primary target (for instance mini-monovison; full monovision comes with substantial tradeoffs, so more risk of not tolerating it) and your backup (distance in both eyes or near in both eyes for instance). Then you have reasonable room to work with the eye that won't change from final target either way to try for some EDoF in that (say planning on -1D of adjustment to get to target and maybe gain a bit of EDoF). But for eye you aren't sure of focal target, you could pick a target half way between your two possibilities (trial and fallback) and that way, you try something close to that early on, and decide which direction to adjust sphere based on whether you want more or less monovision. Say you were considering anywhere between plano and -2.5D full monovision in the near eye (High risk of not tolerating -2.5D, so that is likely further than you would go). You could target -1.25D and then if you want more monovision than you ended up with, you'd adjust more myopic. If it started to bother you, you'd adjust to less. This way, you'd have a max of 1.25D (plus surgical targeting error, depending on direction) to adjust in one direction, and still have some margin to come back partially if you overshoot. Whether you get any EDoF at all would be a crapshoot, but at least you're able to properly trial monovision strengths (assuming your distance eye is near target at that time, either done first, or at least earlier in adjustments if needed) since your cataract advancement won't let you do so pre-surgically.

One complication here is if you have post-surgical astigmatism, you may need the astigmatism to be reduced fist, say first adjustment only treats astigmatism and subsequent adjustments focus on sphere and any remaining (hopefully minor) residual astigmatism. From what I understand, that should leave you max flexibility in sphere diopter changes as it would polymerize fewer macromers than doing sphere adjustment at same time, at the expense of potentially needing 4 or more adjustments, so definitely something to verify with surgeon and LDD staff if different. However, I think you have to carefully prioritize maximizing sphere adjustment range available given the 2D sphere adjustment specification since you can't do pre-surgical monovision experiments. If you do one eye first (whichever is the distance you'd keep for the fallback), you could still use that one to get an idea how much ADD power you need for reading vs plano (post surgical eye would have no cataract or accomodation, so best proxy for reading ADD power in the other eye).

Julie, I forgot to mention above that if you plan on smaller adjustments for your near eye from say -1.25D, you would leave yourself more room to reverse it if you go too far. Too much adjustment at once increases risk of running out of macromers if you overshoot by a lot and have to reverse a large adjustment. But smaller adjustments let you keep going in the same direction, stop, or reverse direction without using up too many macromers. But you'll want to discuss that with surgeon/LDD staff before starting that approach as it may well require more than 3 adjustments and they need to be willing to do that. I personally experienced a 4th adjustment which added 0.5D (it may have induced a 0.25D astigmatism, or that may simply be in measurement error as it is so small, I was told 0.25D astig can change from day to day in the same person), so I know 3 adjustments is not a hard limit (though it could be the FDA approved tested limit, so 4 or more adjustments may be an off-label use - I'm not sure).

Also, you can test more near adjustments post surgically once any astigmatism is minimal by using a reading glass lens. I did this to see if night driving would be problematic by looking at headlights through reading glasses at night in my near eye. Need to make sure to wear the supplied UV protective lenses at all times (one of them has +1.5D readers built in). That way, between adjustments, I could trial how much more near adjustment I could handle without affecting night driving. You could try the same to test depth perception and to see how it affected your distant vision.

The level of advancement of your cataract forces you to defer more of your testing to post surgical between LAL adjustments.

Going from memory which is dangerous, but I thought they adjusted cylinder and sphere in the same step, based on the Mayo Clinic video.

Ron, you are correct that they do normally adjust both in same adjustments. I'm suggesting an exception may be warranted in a case with significant astigmatism present and very little pre-surgical experimental results on targeting possible due to advanced cataracts. Idea is to minimize use of macromers to provide better experimental conditions to test mini-monovision if sphere is close to target but cylinder isn't.

All, please note that I am a patient sharing my own experience and not a doctor and nothing I've said or say should be considered medical advice. Always check with your own doctor/health care professional for specific medical advice!

"I see better in my distance eye with 1.5D reading glasses than I do in my near eye with ~1.5D (LAL LDD) near adjustment with no glasses."

That is very interesting, JDvision. Do you know why this is? Do you think your distance eye is simply better than your other eye? Or maybe the LAL in your distance eye is performing better than the other LAL? And if the latter, why would that happen?

Phil, you asked why I may read better with a 1.5D reader on my near plano LAL eye than with a -1.5D near LAL eye with no glasses. First thing that comes to mind is vertex distance (glasses are further from the eye than an IOL, and that affects the power). That effect appears small at that power level (I calculated equivalent of only -1.53D for a contact lens prescription). It could be differences in eye geometry between the two eyes as their pre-operative natural prescriptions were different. If eye lengths were also different (I never saw the biometry data), they could be affected differently by the same prescription). Or maybe a difference in DoF resulting from plano corrected with -1.5D compound lens effect versus a single -1.5D lens. I'm just speculating here. I really don't know why the glasses test in the near plano eye was not a completely accurate estimate for my near eye IOL prescription target. I doubt it is a performance difference between the two LAL lenses, as both eyes were measured by the same phoropter and the same person, and the claimed 1.5D glasses was the one provided by RxSight in the UV protective eyewear, so I'd be surprised if the glasses lens prescription was inaccurate. I never cross-checked it with off-the-shelf readers though to see if it was accurate, but I'd be surprised if it wasn't.