What is a reasonable or safe target for a high myopic patient choosing monofocals?

hi Kathleen,

Are you highly myopic as well? have you had your cataract surgery? if so, did you choose -1 as your target? whats your residual myopia after surgery? what monofocals did you get?

my surgeon chose -1 but that was before biometry. i will see what he chose after biometry next week.

Sam, ask for a printed copy of the IOL calculation sheet which shows the predicted outcomes of the range of IOL powers in the range that you need. That way there will be no miscommunication between you and surgeon on what to expect from the power selected. This predicted power for a non toric lens will be on a spherical equivalent basis which is sphere plus 50% of the predicted cylinder. Sometimes patients/surgeons can get fixated on sphere only. It is the spherical equivalent total that is most important.

I do have high myopia but in my case it's more "extreme myopia." So I am not eligible for most iols since they don't come in my Rx. I need about a +2D to +5D spherical power depending on refractive target. I haven't had surgery yet

Ron can you explain how the predicted power is equivalent to sphere plus 50% of the predicted cylinder? my astigmatism might be from the natural lens, how do I translate that? for example, my sphere is -11.5 and cylinder is -0.75, how do these numbers translate into a predicted oitcome of the IOL?

The IOLMaster and Pentacam will calculate the predicted sphere and cylinder outcome based on the dimensions of the eye and the topography (slope of the cornea). They are not based on your pre-surgery refraction because they are a mix of your natural lens impacted by the cataract, and the shape of the cornea. The natural lens error and cataract influence are removed by the surgery. The IOL only needs to correct for error caused by the shape of the cornea and dimension of the eye.

when you get your optical biometry measurements it will give you axial length and cornea measurements which will give you the suggested iol powers. With only 0.75D of cylinder in your glasses Rx it doesn't sound like you have a lot of corneal astigmatism, but you won't know exactly how much you have until you get the biometry done.

Corneal astigmatism will drift over time. It's very slow, as in a change that happens over decades rather than years. It tends to drift from with the rule astigmatism in young people towards against the rule astigmatism in older people. But it varies from one individual to another so you can't predict exactly how it will change in each eye.

i just mention this because the surgeon at my first consultation suggested limbal relaxing incisions to correct my low corneal astigmatism (0.25D in my left eye, 0.85D in my right). i thought it was silly since i had so little astigmatism in my left eye, and it would drift over time anyway. My right eye astigmatism might be worth correcting if we were going for spectacle independence, but as I'm targeting -1.5D and plan to wear glasses after surgery I don't see any advantage.

Do you obtain the power of the IOL from the calculation sheet? one surgeon targeted -0.2 and selected a 8.0D IOL Alcon Clareon with a predicted target of -0.31. with the larger errir of fluctuation for high myopes, i am afraid i will become hyperopic... whst have your surgeon suggest for a target or predicted outcome?

are IOL master and Pentacam separate instruments? i went for one measurement with the first surgeon and it was just one instrument (i saw IOL master on the instrument) and entire measurement took about 5 minutes. Did they get all the measurements?

Do the different predicted outcomes from the IOL calculation sheet have included the sphere+cylinder (cornea) and subtracted natural lens' astigmatism, thus give a predicted outcome? or the surgeon has to do some calculations to remove natural lens errors and astigmatism after biometry so the predicted outcomes will include the subtracted natural lens errors & astigmatism?

I felt my cataract a bit worst since my measurement. Does that mean the measurement won't be as accurate then? is it better to have the measurement done a week or two weeks before surgery?

Yes, the IOLMaster and Pentacam are different instruments. The IOLMaster measures the axial length of the eye as well as the slope of the cornea. The length primarily determines the sphere power of the IOL needed. The slope of the cornea determines astigmatism, and in particular the difference between the maximum and minimum slope at the different angles. The Pentacam is optional but most surgeons still use it especially if a toric lens is being considered. The Pentacam generates a coloured topographical map of the slope of the cornea. It not only measures astigmatism, but also determines how uniform it is. In some cases astigmatism can be irregular instead of symmetrical.

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The surgeon does not have to do manual calculation to subtract out the natural lens power and cataract issues. It simply ignores the lens and bases the calculation on the axial length of the eye, and the slope of the cornea. Neither are changed by the cataract surgery. If a Pentacam is also used to measure slope and astigmatism the surgeon may then compare the predicted astigmatism from the IOLMaster to the Pentacam and decide which to use. If a non toric lens is being used, I suspect they only use the IOLMaster measurements.

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Cataract progression should not impact the measurements taken. The only benefit would be to get a second measurement to determine if the reading is reliable. I went 18 months between my eyes and the surgeon did do the IOLMaster and Pentacam over for the second eye. Not sure what measurements he finally used, or if they changed much because I was not smart enough at the time to ask for the IOL calculation data sheets.

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There might be some benefit in having them measure the eye with the Lenstar LS-900, or Alcon Argos, if the clinic have them. They are the alternatives to the IOLMaster, and would provide a second opinion on the critical measurements of the eye.

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I think the IOLMaster is a very good instrument and will not likely be the source of error. The IOL calculation formula is much more critical. I would ask to see the predictions using the Barrett Universal II, Hill-RBF 3.0, and EVO 2.0 formulas to see if they are predicting similar outcomes. And if they don't then I would lean toward depending on the Hill predictions.

With a target of -0.3D there is a good chance that you will end up hyperopic. Many surgeons do not think it is a bad outcome for patients to be slightly hyperopic because the patient can still see 20/20, and they consider that preferable to targeting more myopia. This is because some patients get very disappointed if they have to wear glasses for distance after surgery. If it's not extremely important to you to be glasses free for distance after surgery, and you would like more uncorrected intermediate and near vision, then you may want to ask the surgeon to target intermediate vision, such as -1D of myopia. Looking at the research articles, greater than 50% of high myopia patients land within 0.5D of their refractive target, and most land within 1.0D. So with a target of -0.3D you should be more than 50% likely to land somewhere between +0.2D and -0.8D, and almost surely (about 80% likely) to land between +0.7D and -1.3D. Here's an article I found with a quick google search that showed 53% of high myopia subjects got within 0.5D and 81% got within 1D. Source= https://link.springer.com/article/10.1007/s10792-020-01684-y

The main reason for big refractive surprises in high myopia patients is inaccurate axial length measurements due to the presence of a staphyloma-- a backwards curve on the retina. I have been told I have staphyloma and suspect it has affected my measurements, but you have less myopia than me so maybe you don't have staphyloma. If you don't then your axial length measurements should be very good. Just to give you an example of my level of myopia, my glasses Rx is around -17D and my recommended iol powers are closer to +2D to target plano.

As a high myope I honestly prefer a little bit of myopia, most of what I need to see is intermediate or near distance, and Id rather wear glasses for driving than for near work.

Also there is a possibility of drift over time, both with spherical power and with astigmatism, and I can always update my distance glasses when that happens, to have the best possible vision for driving.

to answer your question, I have seen four different surgeons, one recommended targeting -0.5D, one didn't have a recommendation and asked me what I'd prefer, and two recommended targeting one to two diopters of myopia to avoid a hyperopic overshoot.

you can use an online iol calculator such as the one available on ESCRS if you have a copy of your optical biometry measurements to plug in. And how bad your cataract is shouldn't change your refractive target, the only thing that can happen is in very advanced cataract it can get so cloudy that the machine can no longer see your retina clearly or take proper measurements.

hi i sent a reply earlier but it got stuck waiting for review.

Two eye surgeons that I consulted recommended targeting -1 to -2D of myopia for my refractive outcome in order to prevent a hyperopic overshoot. I read somewhere that about 50-60% of high myopia patients land within 0.5D of their target so for -0.3D target that is somewhere from +0.2D to -0.8D outcome. about 80% land within 1D so that would be +0.7D to -1.3D. So yes you could definitely end up hyperopic with a target of -0.3D. The main reason for a big refractive surprise with high myopia is the presence of staphyloma which can mess up the axial length measurement. if you do not have staphyloma then you shouldn't be that different from a normal patient in terms of refractive error, so long as the surgeon uses one of the formulas that are optimized for predicting iol power in high myopia.

i also consulted a third surgeon who recommended targeting -0.5D of myopia and said he had a way to double check the Rx in the OR, after removing the cloudy lens but before implanting the iol, so as to avoid a hyperopic overshoot.

keep in mind that your eyes can drift a little after surgery, so the refraction you have on post op day 1 can change as your eye heals. effective lens position can change as the capsule shrinks. other things like swelling and inflammation can also affect your eyesight temporarily

to calculate iol power you just plug the values from your optical biometry measurements into an online iol calculator. make sure you are using a good formula for high myopia and also that you select the correct lens

The cataract being worse shouldn't affect your measurements unless it was a very advanced cataract that was so opaque they couldn't take measurements through it.

i had measurements taken one year apart and the major change was my lens thickness increased as the cataract progressed but I dont think it affected my iol calculations at all. i don't see why it would matter if you did measurements one or two weeks before surgery. i was told to stop wearing contacts five days before measurements do that my corneal measurements weren't affected by the contact lenses.

the instrument that one surgeon suggested to measure more accurately during surgery is it the ORA? I know my surgeon has used it before with a patient and i will ask him if he thinks i will be benefit from it.

do you know much about ORA and if it is suggested for use in high myopes?

my second measurement with this cornea specialist is next week and i will know what's the actual target he will use. he had suggested -1 on his note when i saw him for initial consultation.

I recall two contributors here that used the ORA system. One got improved results from it, and the other did not.

A 2021 study concluded ORA may have some advantage over pre-operative formulas in highly myopic eyes with certain characteristics.

"Conclusions: ORA demonstrated similar refractive results to the Barrett True K formula in post-refractive eyes and to the Barrett Universal II formula in highly myopic and hyper-opic eyes and may provide additional benefit for eyes with steeper corneas or an axial length of greater than 27 mm."

My doctor swears by ORA and uses it routinely. But I have not seen evidence that it is materially better or worse than good preoperative measurement and calculation.

Sorry but the surgeon didn't tell me how he would check my Rx in the OR. I can only assume he uses the ORA system that folks on this forum are talking about. He knew I had extreme myopia and seemed very confident about targeting -0.5D. But I didn't get the impression that he would consider it a miss if I ended up +0.25D.

i used ora for my first surgery. it was very accurate but not really different from iol master. it was only a 100 extra. second surgery after 4.5 years the same surgeon said he doesnt use it anymore as he has been burnt by it. i dont think it will help for high myopes as it is same as iol master but just after removal of cataract lens.

LAL should help with refractive surprises.

+0.25 D is not a disaster, especially if that is a sphere only and there is some astigmatism to offset it.

The surgeon that targets my L eye at -0.2, I have asked him about the "what if" i become hyperopic. His answer was simple "use glasses to adjust hyperopia". Why do i feel that he doesn't understand the uncomfortableness of a high myopic patient becoming hyperopic? same as what you mentioned that this surgeon might not think going to a positive number is a miss.

do you have LAL lens? none of my surgeons offer this lens.

i do not. lal = light adjustable lens. you should be able to change the refraction of the lens upto few months after the surgery using light and then lock it in.

Keep in mind that being +0.50 D and -0.50 D will provide essentially the same distance vision. The only difference will be in how near each person will be able to see. There will be a small advantage to the one at -0.50 D. But for the 95% of people that select distance vision in both eyes, this is not all that big a deal as they will be forced to use reading glasses or progressives to see near in any case.

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It does become a more important for those wanting mini-monovision to be eyeglasses free for both near and far.

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I am not totally convinced by the theory that all myopic people want to be myopic after surgery. This is a convenient solution for the surgeon however, as it is easy to hit a wide target for near vision and assume the patient will just use eyeglasses to fix the distance problem.

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In short I don't think it is a total disaster to be slightly hyperopic, but the sweet spot still is to be slightly myopic.

i like to be myopic free if possible, but i dont want to end up hyperopia. I am not sure how accurate the predicted outcome will be after surgery. I hope my surgeon will answer these questions for me.

Pretty much everyone WANTS that, but quite frankly it is unrealistic to expect to be 0.00 D plano, if your target is distance. The LAL system is probably the best approach if perfect distance vision is the objective. It should get you within 0.25 D of that target unless you have unusual eyes. But, LAL can cost you $10,000+ per eye and is very time consuming especially if you have to travel for the series of adjustments.

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It may be more practical to think in terms of what is acceptable rather than what would be the ultimate perfect solution. There are certainly some ways to improve your odds of getting a good outcome though, short of LAL.

Pretty much everyone WANTS that, but quite frankly it is unrealistic to expect to be 0.00 D plano

True. Almost no one is perfect 0 plano with 0 astigmatism… cataract surgery or not.

The Hill-RBF formula used in that study has been updated from the version 2.0 they used to version 3.0, with a significant increase in accuracy, and especially in the eyes with a higher axial length.

Correction: The $10,000+ would be for two eyes using LAL, not one eye.

Sam,

Don't "hope" your surgeon will answer your questions. Don't leave his office until he does. Insist on straight answers. That is your right and those are your eyes.

even if they got you to a perfect 20/20 on the day after surgery, there is some variability in effective lens position as you heal, and your Rx can drift. Have you considered the Tecnis Eyehance iol? It is a monofocal plus iol so it has a little bit of extended depth of focus, which means it has a broader landing zone, and if you end up a little bit off your target you should still be able to see distance. That way you can target a little bit of myopia and get a little better range in what you can see.

I don't think the LAL would be recommended for a patient with high myopia, as it is made from silicone and can be damaged if a patient receives an injection of silicone oil. Patients with high myopia are at a higher risk for retinal complications during and after surgery and if they get a detachment and need retinal surgery that requires an injection of silicone oil it would stick to the silicone iol and ruin it.

I think a gas bubble is the preferred method in all but the most advanced cases but that's an interesting consideration. Would an intact posterior capsule offer no protection from the silicone oil?

Actually while J&J talk about a broader landing zone for the Eyhance I do not see any evidence of that in the defocus curve. The defocus curve does have a slight extension to closer distance but that is well away from the peak acuity point. J&J compare the Eyhance to the Tecnic 1 which has the least depth of focus of all monofocials so it looks good in comparison. A recent study by Alcon found that the extension was insignificant when compared to the Clareon which has more depth of focus than the Tecnis 1.

When you go in for your consult that is the optimum time to ask for your IOL calculation sheet. Your files will be up on the computer and it is just a click of the mouse for them to produce a printed copy. I would say that you want the paper copy so you can better understand what the power steps are and what the predicted outcome is from each. If you are considering mini-monovision you should ask for the target to be set for -1.50 D so it will display the power steps around that outcome.

I am having the same problem as sam36130. Is it a time issue with an ophthalmologist? Even when I pay for an extra appointment, I receive some new information, which creates another question.

If you've already agreed upon the light adjustable lens, would there be an IOL calculation sheet? I guess there would be! Because if the LAL target is +0.25D they would still need to calculate it . Does the IOL calculation sheet show the instruments that were used for the calculation?

Most ophthalmologists are in a rush because of high patient volume and reduced reimbursement from Medicare and private insurers. But do try to get your questions answered. Sometimes contacting the Office Administrator about your concerns can get you more attention.

Yes, they still have to do the power calculation to get near to the starting point refraction for each eye. Most sheets will indicate the instrument somewhere. In the case of the IOLMaster 700 it seems to get identified as a line at the bottom of the page.

After going through the ordeal with finding a surgeon and asking questions, i do find most surgeons don't give straight forward answer, or they just can't tell me. for example, none of the ophthalmologists i have seen told me that i need surgery. They only say if you want to proceed with surgery, they can arrange that. I also asked then if I will benefit from the surgery, most of them answered "depending on what you want to achieve".

i am in the US and now very exhausted from my research on cataract. i have been reading and asking questions in forums like this. at the end, all i can do is hope for the best. Iol selection and target refraction are something important to discuss with surgeon, but at the end, i have to relie on the surgeon's experience because my measurements might be different from other patients, and only an experienced surgeon can based on his experiences to predict the best outcome for me. i believe my surgeon is an experienced and skilled surgeon as i have texted with 10 or more of his previous patients and they all highly recommending him. he also reversed a botched cataract surgery on a patient. so if he can do lens exchange, he must have very good skills. As my other surgeon (first one) told me that he doesnt do lens exchange.

However, i also know someone that had surgery with a world renowned surgeon but her refraction was missed, target was -2 in both eyes and ended up -2.5 and -2.75. She was high myopic around -7 before surgery. So now she can see very close 3-6" without correction but need a -1 & -1.5 contact lens to see well.

My surgery is on Jan 9 and i am not even sure i am ready! for those of you that already has your surgery, what mindset did you have going in? did you think you have done enough research to have no regrets?

unfortunately the surgeon i am having surgery with only offer the B&L Envista. i read that this IOL is forgiving in its central placement as well.

i am fine with being a bit myopic around -0.75 to -1.5. I think with that level of myopia, i can still drive without glasses (20/40)?

Can i have the technician print out the calculation sheet for me when i go in for my measurements? I wont see my doctor until the day of surgery but he will give me a call after measurement to answer my questions. i plan to discuss my target refraction with him then.

yes i feel exactly like that. There are always more questions after talking to the surgeon. should i just close my eyes snd put everything in the surgeon's hand?

"My surgery is on Jan 9 and i am not even sure i am ready! for those of you that already has your surgery, what mindset did you have going in? did you think you have done enough research to have no regrets?"

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I was not as well informed as I should have been even when I went into my second surgery in February 2022. I was not smart enough to ask for a copy of the IOL calculation sheet. And, I really should have gotten a toric lens. I partly blame the surgeon for that one, as the time for discussion on whether a toric would benefit me was cut short.

The enVista is a good choice, and in my opinion better than the Eyhance.

For sure the technician can do the print out and is probably the one that does it for the surgeon. The only question is if there are clinic rules that require the surgeon's permission. Tell them you would really like to have a copy ahead of time so you can think it over before you meet with the surgeon to make the final target decision. They should be happy to do that as it will make you part of the decision process.

Sam, it sounds like you have certainly done your due diligence. Most patients have done far less "due diligence" than you have, and they are generally satisfied with their outcome. You have a highly skilled and experienced surgeon who comes well-recommended. You have done all you can do and you should done fine. My own mindset was that my cataracts were so far advanced ( I delayed surgery for years to care for my mother) and my vision was so poor, that I just wanted to get it over with. That was after I had seen two other cataract surgeons, emailed three more who were ophthalmology professors, Google info on the internet and went to this forum.

That lens looks nice! and it's available down to 0D! I wonder why I was not offered it.

Good luck with your surgery!

Yes, I agree that it is a good lens and does seem to be available from 0.0 to 10.0 D in 1 D steps. It may be a very good option to consider. My brother has this enVista lens in a +15.0 D power and is very happy with it.

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If one needs in the +8.0 D range it does make the power choice a little more critical. One step in lens power is going to change the sphere outcome by about 0.75 D. You would not want to be off target by one step. And, it may limit the choices for target outcome to some degree.

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The lenses offered by clinics are often driven by commercial decisions. Most will not offer all lenses from all companies and they tend to get "in bed" with one or at the most two different suppliers. And, there is the issue of what lens the surgeon is most experienced at using.

for my first surgeon, he wouldn't even considered toric lens. he said toric lens are not as forgiving in their placement, a bit rotation of lens can make patient to see blur.

second surgeon briefly looked at my automated refraction (taken via the balloon image instrument), said my astigmatism is likely in my natural lens as my cornea doesnt show much astigmatism (i think based on the cornea image by the same balloon image instrument), so i dont need toric.

In the US, i heard surgeons don't suggest toric if astigmatism is -1 or less. but there are people with -0.75 still paid for a toric lens. this is again very confusing as it might depends on the surgeon habit!

Lynda,

Thank you for the encouragement!

How did you eventually pick your surgeon? what lens and target refraction were chosen? Do you like the outcome?

Hi Ron,

from my first surgeon with a target of -0.2, he came up with a 8.0D IOL for me with a predicted outcone of -0.3. He will be using Alcon Clareon Monofocal. I am a bit apprehended of the predicted outcome of -0.3 as it is too close to plano and the surgeon has mentioned the predicted outcome is not very precise. So as Ka mentioned, i am very likely become hyperopic (which i hope i wont become).

The second surgeon using Envista, he had suggested -1 with no measurement yet. I wonder if that has to do with the limitation of power in the 0.5D for this lens. I should get a better idea after my measurements and discuss with him on Wednesday.

there can be an issue with rotational instability in the larger capsular bag of high myopes. so toric iols can rotate and that would not be good at all. if you had a lot of astigmatism, chose a toric iol and then they found that the iol was rotating and needed o repositioning, then they can also implant a capsular tension ring alongside it for stability.

but if you only have a small amount of corneal astigmatism then you don't need to worry about it. Astigmatism drifts over time anyway and after 10 years it can have changed enough that you might need corrective lenses either way

When it comes to deciding if a toric is needed or not, you need the prediction from the IOLMaster and possibly the Pentacam. I do not believe you can predict it accurately any other way.

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To me a surgeon that is not confident enough to use a toric lens does not inspire confidence their surgical ability. Perhaps the surgeon does not cater to patients expecting glasses free vision, and just depends on eyeglasses to correct the astigmatism. This makes practical and economic sense if there is no expectation to be eyeglasses free.

A predicted outcome of -0.30 D if the Hill-RBF 3.0 formula agrees is a reasonable risk. I am not aware of any data that would suggest these newest formulas have a bias in one direction or the other. Some of the older formulas did have a bias, and a correction method was used to compensate for the bias.

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As an example of the potential issue with the enVista would be if a +8.0 D gives you -0.30 D then the two power choices on either side of that would be -1.05 D and +0.45 D. If distance vision without glasses is the priority then I would not consider either of these two choices to be acceptable.

i have heard of a capsular tension ring in Asia but not commonly used in the West (Europe and North America). in Asia, some surgeons will choose to use it for high myopes like us but why i haven't heard it from my surgeons? Should it be used as high myopes tend to have larger capsular bag?

Yes, the first surgeon told me tgat he likes simplicity. monofocals set to distance and use readers for close up. if there is astimagtism, he suggests to correct with glasses also. For him, he said the main purpose is to remove the cataract, so when i tried to discuss my target refraction with him, raising concerns of hyperopia, he made it short and said i can use glasses to correct the hyperopia. But hyperopia should have good distance vision and need to correct for close up, so i am not sure why he said i can use glasses to correct my distance vision if i become hyperopia.

That's one reason why i chose to go with the second surgeon because in my initial consultation with him, he was more concerned with my eyes balancing after L eye surgery. He also put down on his note to discuss mini monovision with my optometrist even though we didnt discuss any mini monovision options during the initial consultation. Do you know why the surgeon said to discuss mini monovision with the optometrist instead if himself?

My measurement with his tech is on Tuesday, so maybe after the measurement, i can discuss with this second surgeon about target refraction and the possible mini monovision?

Does mini monovision not suitable for sensitive eyes? Both my eyes have been almost equal in precription throughout my life since childhood. Current glasses prescription has both eyes differed by 1.0 diopter. But this 1.0D difference was over a period of years and not sudden. Does that mean i might not get used to mini monovision of even 1.0 diopter difference? would it be a reason that the surgeon likes me to discuss mini monovision with my optometrist (he has been my contact lens and glasses optometrist for more than 20 years)?

Ron, do you mean if 8.0D Envista would give a predicted outcome of -0.3, then a 7.0D Envista wouid give +0.45 and a 9.0D Envista would give predicted outcome of -1.05?

In that case, the 8.0D would be the best choice for glasses free in distance vision?

"should i just close my eyes snd put everything in the surgeon's hand?"

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No, not everything. I think you should make sure you and your surgeon are in clear agreement on your goals/preferences and the range of expected outcomes. It is reasonable to leave technical details in the doctor's hands.

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My operation is the day after yours. Good luck!

I have not heard of using a capsular tension ring. It would seem to have the potential to significantly impact the effective lens position in the eye and the refraction outcome accuracy. However, the impact may be lower with a very low power IOL.

I was offered a CTR in London, UK, because they were also planning to implant the Zeiss CT ASPHINA 404P, which is a flexible hydrophilic acrylic iol with only a 11mm diameter and it is not stable enough on its own in extreme myopia. (My axial lengths are 31-32mm) In the US I was offered a 3-piece 13mm diameter Alcon iol that the surgeon said would be plenty stable enough on its own, with its more rigid angulated PMMA haptics. He said he would not automatically place a CTR in high myopia. I asked if there were any downsides and he said the only risk with a CTR is when they place it in the eye, for a brief moment it applies some force that could potentially damage the capsular bag if it is weak to begin with. But once it's in position, there are no downsides. My UK surgeon said she had implanted over 500 CTRs and thought it was straightforward and low risk. A second surgeon I consulted in the US said her decision on whether to implant a CTR would be made based on intraoperative findings-- specifically whether she thought I had weak zonular support.

I think there is a lot more high myopia in Asia-- the research articles I read from China speak very highly of these patients because we tend to be very highly educated-- the high myopia tends to develop as a result of a childhood spent studying indoors instead of being outdoors. I don't like that US doctors seem to see us more as an oddity or edge case.

I've read articles from China that recommend routinely implanting CTRs in extreme myopia and I noticed that they also tend to use a variety of iols, including the hydrophilic iols. Also CTRs are thought to help inhibit the development of PCO.

I think maybe some US surgeons just aren't that familiar with CTRs or comfortable using them. And maybe they feel if they aren't truly necessary it's better to leave them out?

I don't know. It's all so confusing that I still haven't had my surgery.

"But hyperopia should have good distance vision and need to correct for close up, so i am not sure why he said i can use glasses to correct my distance vision if i become hyperopia."

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No. My best understanding of hyperopia is that a +0.5 D outcome is just as bad for distance vision as a -0.5 D outcome with an IOL. With natural lenses that have some accommodation (ability to change power) you can tolerate some hyperopia, but with IOLs there is zero accommodation so +0.5 is just as bad as -0.5 D.

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Not sure why the surgeon would defer a mini-monovision choice to the optometrist other than to just avoid making a decision/recommendation. The normal conservative way to get into mini-monovision is to do a stepped process.

1. Target the dominant eye to distance with a nominal target of -0.25 D.
2. While the eye is recovering use a contact in the non operated eye to correct it to -1.50 D to simulate mini-monovision. At this time you can also use OTC readers to see what reading vision would be like with the operated eye using +1.50 D readers to simulate what -1.50 D would be like to read with.
3. If you like it then after the first eye has fully recovered and the surgeon has had a chance to recalibrate their formula based on the first eye outcome, then they target the second eye to -1.50 D.
4. If you don't like it, then target the second eye to -0.25 D for distance, and count on readers for near vision.
5. I suspect a big part of being able to accept mini-monovision is your personal attitude about it. If you are convinced it will not work, then it will not work. But, if you are willing to give it a chance then doing the simulation is best. I have never had a big split between my eyes after correction in my lifetime up until I tried mini-monovsion, and I had no issue adapting to it. I found it a bit weird to walk around with no glasses or contacts at first, but that feeling quickly went away.

I had seen two other cataract surgeons, emailed three more who were ophthalmology professors, Googled info on the internet and went to this forum.

The surgeon I used asked me what kind of vision I wanted after cataract surgery. I told her I spend a lot of time on the computer, so I asked her to target intermediate vision. The IOL was the Tecnis 1 monofocal. She and I both expected I would continue to wear eyeglasses, only the lenses would be thinner. As it was, it seems that because of where the axis fell, my 2D of uncorrected astigmatism, and just plain luck, I ended needing readers only for sustained reading of printed material. And rarely, if I am driving at night on a country road, I will wear my distant vision eyeglasses.

My surgeon was a religious person who went on mission trips to third world countries to do cataract surgery. She said the patients she saw had rock-hard cataractsl, and that my +4 cataracts were nothing compared to what she was used to.

On the morning of my surgery, she told me she had prayed for me. So did my parish priest and another priest that I knew. I also prayed myself. I will pray for you, Sam.

I will pray for you, Phil. I think both you and Sam will do fine.

Thank you, Lynda111, I do appreciate it!

Hi Phil,

Is this your first eye surgery? Have you selected your lens and target refraction? May i ask what's ate they? Did you discuss them with surgeon or surgeon suggestions but you agreed?

good luck to us!

"As it was, it seems that because of where the axis fell, my 2D of uncorrected astigmatism, and just plain luck, I ended needing readers only for sustained reading of printed material. And rarely, if I am driving at night on a country road, I will wear my distant vision eyeglasses."

Lynda, the 2D above is the power of your IOL? If so, you were high myopic as well? what was your target refraction and actual refraction after surgery? did you have the second eye done? with mini monovision?

Hello Sam -

This will be my first cataract surgery, but not my first eye surgery - I had LASIK back in the 1990s. I chose the Light Adjustable Lens, so the refraction target is somewhat flexible. My doctor proposed -1.25 D for starters, and I am thinking I will want to end up around -2.00 D after adjustments. The eye with the cataract is my near-vision eye, so I want to make sure I retain good reading vision with that eye. My other eye is still good for distance (I use monovision).

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I did discuss with the surgeon, but I still have an email in to him to make sure we are on the same page for the initial target and adjustment strategy. As you and Julie said above, it can be difficult for a patient to nail everything down in a consultation with a busy expert. In my case, much of the discussion was around the choice of lens - I refused the lens my doctor recommended. He was willing to consider my preference and get on board with it, which is more than I can say for some other surgeons.

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I hope everything goes well for both of us next week.

Phil,

Did you have monovision after lasik? i do not know that was possible in the 90s.

For me, i am not sure if i can get use to even mini monovision. Like Ron has mentioned, after my first eye surgery, i can play with contact lens in my second eye to simulate that. unfortunately, my first eye is my non dominant eye, so not sure i can still do mini monovision.

"Did you have monovision after lasik? i do not know that was possible in the 90s."

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Yes. I was only in my mid thirties, but old enough that reading glasses would be needed in a few years. My doctor (same guy I am using for the cataract 28 years later) offered monovision as a way to avoid reading glasses for another 20 years or more. I was afraid it would bug me to have different vision in my two eyes, but it turned out to be no problem at all. Your mileage may vary...

Sam, keep in mind that it is not essential that the dominant eye be the distance eye, although that is the convention. Some studies have actually shown having a near eye dominant may be better. That is what I have - crossed monovision. So, if your first eye is non dominant you could do it for distance. That is how I got into my crossed monovision - distance first in my non dominant eye, followed by near in my dominant eye 18 months later.

yes if you are used to the monovision, then doing the same after cataract sounds great!

you are lucky to have the same doctor that knew your eye history!

I hope i am not rushing into the surgery as i haven't had my measurements and discussion of final lens and target refraction yet! I also need a contact lens in my secobd eye to balance after surgery.... hopefully these will go well this week!

Sam, I had 2 diopeters of astigmatism in my eyes prior to cataract surgery, which I elected not to correct with a toric IOL. I assumed I would wear eyeglasses to correct it and for distant and near vision. As I said in my earlier post I just asked my surgeon to target intermediate. I didn't go into all the optics and refractive outcome specifics. See my earlier post for more details.

"I hope i am not rushing into the surgery as i haven't had my measurements and discussion of final lens and target refraction yet"

Sam, surely you will have your measurements and final discussion of refraction prior to surgery?

Yes. My measurements today and surgeon said will call me tomorrow.

I am to have contact lens fitted for my second eye thus Friday but i am not sure if i will find one as i am not supposed to have contact lens in my first eye for two days before surgery. So worry!

The tech can only give me my measurements but not the IOL calculation sheets. but she was using 3 formulas for IOL calculation for my surgeon saying different formula is good for particular eye. The formulas she said my surgeon like are Barrett Universal, Holladay and SRK/T. I read the article https://eyewiki.aao.org/High_Myopia_and_Cataract_Surgery

it says the SRT/K is more accurate for high axial length eye. My axial length is about 27mm. The target refraction used was -1. I will talk to surgeon tomorrow and see what his final choice for me!

If you have the actual measurements you can enter them in the Hill-RBF formula yourself and get your own prediction.

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From what I know of these formulas I would rate the Barrett Universal as the most accurate and the Holladay the worst. Hill-RBF and the EVO formulas are better though.

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That Wiki data you have is old. The Hill-RBF 2.0 it mentions has now been replaced with the Hill-RBF 3.0, and it has a +/- 0.5 D accuracy of 98.4% in eyes with Axial Length > 25 mm.

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See this report and the graph at the end. Holladay 1, and 2 are the worst, and the SRK/T is not much better. Hill 3.0 is best, with the Barrett Universal II second best.

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CRSTG Hill-RBF Calculator: More Data to Further Refine Outcomes A new approach to optimum IOL prediction in any patient Warren E. Hill, MD and Adi Abulafia, MD

The instrument used to measure eyeball length is Lenstar LS 900. Its supposed to have the Hill-RBF but apparently, my surgeon doesnt like to use it. do you think the different IOLs use different formulas? Per formula might not give the best outcome to every IOL?

Dr. Hill says that the Hill-RFB 3.0 formula was idealized for the Lenstar LS-900 instrument, but it works well with the IOLMaster too. Different IOLs will use a different A-Constant. But different instruments should not use different A-Constants.

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This sounds rash, but I think if I was in your situation I would refuse to have surgery until the surgeon shows you the IOL calculation sheets and includes the the Hill-RBF 3.0 formula. Currently the only reasonably good formula that he has used is the Barrett Universal II. If push comes to shove, I would pick the Hill over the Barrett prediction. The best outcome would be to have the Hill and Barrett predicting the same outcome.

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I hope you appreciate that a -1.0 D target is in the middle of no man's land. It is too myopic to give good distance vision, and is not myopic enough enough to give you good reading. You are being set up to need glasses for both distance and near vision.

I found this article which you may find interesting. Goggling this should locate it.

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doctor hill iol power calculations formulas

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The correct site will bring up a graph which lists the formulas and the ranges of eyes they are applicable to from hyperopic to normal to myopic. Some interteresting information from this page:

Holladay I - Developed in 1988 and for the long eye (myopic) range a correction formula called Wang-Koch axial length adjustment is to be used to give more accurate results. Your surgeon may be old school and still using an old formula with a correction applied to it. It would be really bad if they were using an old formula like this without correcting it.

SRK/T - Developed in 1990, and requires the same Wang-Koch adjustment to get more accurate results in long eyes.

Holladay II - Developed in 1996, and requires a Holladay axial length adjustment for long eyes.

Barrett II - Developed in 2014, and does not require a correction for long eyes. Claimed to be excellent for long eyes requiring IOL powers down to 0.0 D.

Hill-RBF 2.0 - Developed in 2018 using artificial intelligence. Not shown on the graph is the Hill-RBF 3.0 which was released in 2021, and has been found to give excellent results in long eyes without correction.

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So it is possible your surgeon is applying correction factors to those very old somewhat obsolete formulas. But, my thoughts are that more accurate results would be achieved with the Barrett and Hill V3.0 formulas.

Here is a direct link to the very useful and informative Dr. Hill IOL Power Calculations Formulas page.

https://doctor-hill.com/iol-power-calculations/formulas/

I am not sure about the IOL calculation sheet. the tech told me they cannot give them out but i can ask my surgeon when i talk to him. i am not sure how much i gain from obtaining them since i will ask him what's his target refraction for me and how will i see in distance ranges.

i found the Hill calculation site but it doesn't let me enter biometry as those boxes are gray out. Where can i get the free version or is there a free one?

Fill in all the information you can on the first page, and then click on the I agree box. It will take you to a second page. Then enter all the data. It should not gray out unless you are entering invalid data.

I got the IOL calculation sheet from my first surgeon. in the target refraction, he put in -0.75. He then selected the 8.0D IOL with a predicted outcome of -0.31. My question is if there is no deviation after surgery and it went perfect, shouid i have -0.31 or -0.75 residue myopia?

I guess i an still confused about target refraction and predicted outcome.

add on to my previous reply:

the list where he selected the 8.0D has the other IOL powers with different predicted outcomes,

+9.00D IOL -0.94 predicted outcome

+8.50D IOL -0.64 predicted outcome

+8.00D IOL -0.31 predicted outcome

+7.50D IOL +0.00 predicted outcome

He chose the 3rd down the list. Does that mean if dverything goes perfectly, I shoukd have a residue myopia of -0.31 or -0.75 (target)?

Should land close to -0.31. Not sure what the -0.75 is about.

The target is somewhat irrelevant as long as it results in the program displaying a range of predicted outcomes that are of interest.

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The predictions are theoretical numbers. If these predictions are accurate you would likely test at -0.25 D as the refraction tests are done in steps of 0.25 D. And the other factor is that there will likely be some residual cylinder so the predicted number is most likely the spherical equivalent of the sphere and cylinder. For example it could actually be 0.0 D sphere and -0.50 D cylinder with the spherical equivalent being 0.0 plus 50% of cylinder or -0.25 D.

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I would also pick the +8.0 D power based on this list if the objective is distance vision. However, my big concern would be whether or not the predictions are accurate or not. Did you notice what formula was being used to make this prediction?

If you got the IOL calculation sheet from the first surgeon it should have all the eye measurements needed to use them with the Hill formula. Have you tried that?

"The target is somewhat irrelevant as long as it results in the program displaying a range of predicted outcomes that are of interest." -- does this mean the target only to calculate the IOL power? once the calculation is done, and if the target is still the desired outcome, then the outcome closest to the target woukd be selected? for example from my list, if the outcome desired is -0.75, then +8.50D IOL would be selected?

"The predictions are theoretical numbers. If these predictions are accurate you would likely test at -0.25 D as the refraction tests are done in steps of 0.25 D." --- if I understand this correctly, outcome of -0.75 would have myopia + 50% astigmatism combined?

I couldn't get it to work. the second page won't let me fill in the biometry numbers.

I use Google Chrome as a browser and I recall the Hill calculator works with it. I have had issues with the Barrett calculator and Chrome, but Edge works. So you may want to try a different browser.

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Second I recall is that some fields are mandatory and may have some limits on what value can be entered. If you want you could post the numbers and I will try entering them.

The target is just a convenience number. If you enter a target of 0.0 D then the calculator will give you the predictions for powers around outcomes of 0.0 D, some on each side of that. If you target -0.5 D then it will list outcomes around that value. The target does not affect the predicted outcome for a given power. If the target is -3.0 D for example it will list powers that will give around that outcome, and you will not see the powers around 0.0 D. It is just to ensure the powers in the desired range are predicted.

I gave the Hill calculator a try today with some data I have for my brother's eyes. I basically entered the birthdate, gender, name, etc and the following measurements:

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AL 25.23

ACD 3.26

LT 4.67

K1 43.71 at 175 deg

K2 44.62 at 85 deg

WTW 11.9

A- Constant 119.2

Target -0.25 D

That seemed to be enough to make it work. I did find it would not calculate until I put in the angles for the K1 and K2. If you don't have them, just put in 90 deg and 0.

From this data I got a recommendation to use a +15 D lens with a predicted refraction (SE) of +0.12 D. That is what his surgeon used, and I think it would have been better to use a +15.5 D lens with a SE of -0.22 D prediction. You can see that choice in the second line.

Ron,

here's my spec:

OD

AL: 27.25m

CCT: 528um

ACD: 3.48mm

LT: 4.08mm

WTW: 11.53mm

OS

AL: 27.31mm

CCT: 534um

ACD:3.52mm

LT: 3.82mm

WTW:11.58mm

Thanks for helping me enter to the Hill formula. if you can choose lens, use Envista.

listed my spec but it is not showing...

My postings are under review... here is another one only for my L eye.

AL 27.31mm

CCT 534um

ACD 3.52mm

LT 3.82mm

K1 44.61 @ 24

K2 45.13@ 114

WTW 11.58mm

Target -1.00

Hope you get these numbers to work! if you can choose the IOL, use Envista. Thanks!

What was your brother actual refraction after surgery? is it spot on?

For some reason this calculator is acting up today in Google Chrome. After you have entered all the data and click on the "Click on the box to Calculate" button, there should be a pop up box that comes up and you have to check the box to indicate you are not a robot... For some reason it is not coming up today. However I opened the calculator in Microsoft Edge and it works.

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For your data I assumed the Lenstar LS 900 instrument and used the 119.2 for the enVista A-Constant, and -1.0 for a target. It displays this:

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IOL(D) Ref (D)

8.5 D -0.25

9.0 D -0.57

9.5 D -0.90

10.0 D -1.23

10.5 D -1.56

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This seems to be in very close agreement with a prediction of -0.31 for a +8.5 D power lens that you reported earlier. If this data is correct and you want distance vision a +8.5 D lens would be the Hill formula pick...

I will try some other formulas later to see what they say.

My brother had a very close to spot on outcome; sphere at +0.25 D, cylinder -0.50 D, for a SE of 0.0 D. It is a bit nitpicky but I think an outcome of sphere 0.0 D, and cylinder at -0.50 for a SE of -0.25 D would have been slightly better, in that near vision would have been slightly better.

Ron, I found a Hill calculator online. Very cool! And a google search tells me the Eyhance A-Constant is 119.3. So I plugged my IOL Master measurements into it and it's prediction on my one IOL eye was closer to the actual result than Barrett Universal II. That makes me think maybe I should go a half power stronger than what my calculation sheet says for the second eye (Hill is closer to -0.5 than -0.75 with a 17.5 power). A couple questions…

1. Are Hill RFB predictions in SE?
2. The calculator asked for three variables that my sheet doesn't show… CCT, AD, n. The calculator worked without them but I wonder how important they are?

For what it is worth I tried the Barrett Universal II and the EVO V2.0 calculators.

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Barrett Universal II

8.5 D -0.43 D

8.0 D -0.12 D

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EVO 2.0

8.5 D -0.44 D

8.0 D -0.12 D

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So the Barrett and EVO predictions are essentially identical and a slightly more myopic than the Hill. Using the +8.0 D lens is a bit too close to 0.0 D for comfort in my opinion, and combined with the Hill having been shown to be the most accurate, I would pick the +8.5 D lens with the Hill predicted outcome of -0.25 D, providing the objective is distance vision.

Yes, the Hill predictions are in SE. Each formula has some optional fields. The most accurate results would be with all the optional numbers included. But if you don't have the data there is not much you can do about it.

So, if this is the eye you will have operated on and your target is distance vision, one potential issue is that if +8.5 D is the optimum power, it may not be available in the enVista lens. However, it is available in the Clareon.

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Hill predictions for the Clareon:

+8.0 +0.11 D (hyperopic)

+8.5 -0.21 D

+9.0 -0.53 D

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Hill predictions for the enVista in whole number steps only:

+8.0 +0.07 D (slightly hyperopic)

+9.0 -0.57 D

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So this is something to discuss with the surgeon. If the enVista is whole number steps only then you go for broke with a 8.0 or go modestly myopic with the +9.0 lens.

The 8.0D of -0.31 outcome is for alcon clareon with IOL master 700.

this is 0.5D IOL more which is equivalent to 0.35D in refraction?

"Hill predictions for the enVista in whole number steps only:

+8.0 +0.07 D (slightly hyperopic)

+9.0 -0.57 D"

Thank you Ron, i will see what my second surgeon suggests and compare these results! Second surgeon uses Lenstar LS 900 and Envista.

Yes, 0.5 D steps should yield about 0.35 D steps in refraction. These steps do not always seem to be that uniform in the predictions. As in the post above the Hill formula predicts these outcomes with the Clareon lens.

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+8.0 +0.11 D (hyperopic)

+8.5 -0.21 D

+9.0 -0.53 D

I tried switching the Lenstar LS900 to the IOLMaster 700, and nothing changed. The big differences are in the formulas. Changing from the Clareon to enVista makes a small change as the A-Constant for the Clareon is 119.26 compared to the enVista at 119.20.

Sam, I am entering your data for both eyes, but I need the K1 and K2 values for each eye.

Ron,

I talked to my surgeon and he suggested to target -0.5 to -1.0 for some buffer to avoid hyperopia. I am fine with a little myopic as long as i wont have the hyperopia uncomfortableness.

hope this post will go through. Here's my K1&K2 #.

R eye

K1 43.88D @175

K2 44.70D@ 85

L eye

K1 44.61 @ 24

K2 45.13@ 114

Thanks.

With your additional measurements the right eye is different from your left by a significant amount. Here is what the Hill-RBF 3.0 D predicts with a target for distance vision.

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And here is what Hill predicts for near vision with a target of -1.50 D for both eyes.

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I hope that helps some. If you are considering monovision it is usually best to do distance in the first eye. Which eye would you do first?

You may also want to try the Kane IOL Power calculator. It is very easy to use. It has a toric option that will give a more detailed result including residual astigmatism (cylinder). The only issue is that it presents cylinder as a positive value and you have to go through the positive to negative conversion to get it into a familiar format. It also forces you to enter values for surgical induced astigmatism. I just entered 0 in both fields and that seems to force SIA to zero. Using Sam's numbers the Kane formula seems to be closest to the Hill 3.0 formula - with a virtually insignificant difference in predictions.

Lynda,

What is the RX for your distance glasses and readers after surgery?

Ron,

yes my right eye is a touch less myopic (-10.5) than L eye (-11.5), so it makes sense if the IOL power is a bit off.

I will be doing L eye first as its the worst cataract eye.