How close can I see with Alcon Clareon monofocals set to distance?

is LogMAR the target my surgeon will set? he told me he usually targets -0.20D, does this mean a LogMAR of -0.20? is thus 20/30 or 20/35? how to convert it to visual acuity?

for a residue of -1.0D, 1/1 = 1, this means i might have 20/40 at 1 ft?

LogMAR and Snellen tests both give a measure of how well you can see/resolve. The Diopters is the reciprocal of the distance (in meters) that the eyes are best focused at.

So if he achieves -0.20D, the best focus would be 5 meters out. Moving out to infinity will still give really good focus.

Don't try to read much into the next paragraph. It is awkwardly stated:

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But I think the normal IOL cannot be implanted and achieve the target reliably that close. If the process gives a result of plus or minus 0.5D, then a target of -0.2D could get you into a bit of farsightedness. I have to believe that if he is able to use that as a good target, that would be doing some laser touch-up potentially. If that doctor can achieve the target within 0.2D, that is much better than the norm.

for a residue of -1.0D, 1/1 = 1, this means i might have 20/40 at 1 ft?

It certainly does not mean that.

LogMAR is a visual acuity measurement with 0.0 being about 20/20. Surgeons target IOLs in diopters. A diopter is the power correction needed to bring you to plano or peak vision. If you need 0.0 correction that is perfect vision. If you need -0.25 D, that is the very lowest step of myopia that can be measured and prescribed. It is near perfect vision and probably still 20/20. If they hit 0.0 D correction one may get 20/15.

i havent discussed much about my R eye since it has t affected my vision. i am very active, and 49 years old. i think i have early cataract due to my high myopia. i like to run and hike, so seeing clear at distance is good for me not to need glasses with sweat all over my face.

on the other hand, i havent needed readers yet to read and computer work. even though i dont mind wearing readers for close up, i dont know if i will get used to it.

thank you Ron for a very detailed description. I have been thinking about how to balance with my unoperated eye. my surgeon said i can use a contact lens. I am still worry I moght get headache or disorientate. My surgeon said since i have cataract growing in my R eye, i shouid think about removing it too. his recommendation is like you mentioned, 4-6 weeks after my first.

i haven't discussed mini-monovosion with him. he seems conservative and like to keep things simple. he doesnt like to suggest premium lenses but monofocals set to distance.

Monofocals work well for mini-monovision and avoid the risks of the "premium" multifocal lenses.

hi Ron, may i ask why you had different monofocals in your eyes? did you have them minimono vision?

compare to premium lenses, monofocals suppisedly have less or none dysphoyosia. do you know how to reduce dysphotosia?

My first eye was done about 3 years ago for distance with an AcrySof IQ lens. At that time the Clareon lens was not available here. I had my second eye done for near vision in a mini-monovision configuration about 18 months later. At that time the Clareon had become available and was touted to have a new and improved material. It was said to be more resistant to PCO due to having sharper edges. I selected the Clareon lens for two reasons. One was that it was said to be improved, and the other was that it was not approved for coverage under our public healthcare system and not fully covered. For that reason I paid an extra $300 to have it implanted in a private clinic. That got me in for surgery with only a 3 week waiting period, compared to several months with the public system.

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Ironically my optometrist now tells me that I have some signs of PCO in the Clareon lens, but not in the AcrySof lens.

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Yes, I have mini-monovision with -0.38 in my distance eye, and -1.63 D in my near eye.

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Dysphotopsia from multi-focal lenses tend to be halos and spiderwebs. I do not have halos at all, but do have a starburst effect from LED headlights and tail lights. It is not nearly as bad as what I had with cataracts, but it is there.

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The other effect can be reflections off the edge of the lens. It seems to be mainly a matter of good luck to avoid those. They can occur with any type of lens. I have them very very occasionally with both lenses. I don't consider them an issue.

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If I needed a lens I would not turn down an AcrySof IQ or Clareon. They are both good lenses.

thank you Ron!

Ron, the reflection off the side of your IOL, what does that feel like? is it like a flashing of light or flickering on the side of eye?

do you know anything about the Bausch and Lome Envista monofocals? i read tgat it has no abberations and no glistering like the Alcon. does that mean less dysphotosia?

It is in my very peripheral vision and is a perfect arc shape and is quick like a bolt of lightening. If I move my eye I can make it repeat over and over again at will. It has nothing to do with glistenings. I think it is a simple reflection off the edge of the lens when the light hits it at a very sharp angle, and my pupil is wide open when it is very dark. I might see it once a month or so, and is not an issue at all.

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I like the B+L enVista lens, but I don't think it is any more resistant to optical effects like an edge reflection than the Clareon. The enVista should give a little more depth of focus than the Clareon. Glistenings are not an issue with either lens.

more depth of focus means if set to distance, patient might see a bit more wt intermediate?

how does glistening affect patient's vision? i mean, does glistening means more dysphotosia?

i am checking out two surgeons and they offer different monofocals. The surgeon thats offering B&L Envista is having me work with my optometrist to check my contact lens prescripstion. hopefully i can balance my unoperated eye with a contact lens.

Yes, more depth of focus would mean that you have more intermediate vision when the lens is targeted to distance. And, it would mean slightly better near vision in the near eye in a mini-monofocal configuration.

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Glistenings are a red herring. The Alcon AcrySof lens was the one mainly blamed for having it. They have solved their problems with improved manufacturing methods and it has ceased to be an issue. I asked my surgeon about it and he said he has seen glistenings in IOLs but they have never impacted the vision of the patient. Some manufacturers still insist on raising the problem as if it was serious and current. With all modern lenses that I know if, it is no longer any kind of issue. There are no concerns with the current AcrySof, Clareon, and enVista lenses.

my opthalmologist also said glistening doesnt impact patients' visual very much.

for B&L Envista that is abberation free, how's its contrast sensitivity? i read the depth of focus might improved but moght lose some contrast as compared to Clareon?

I have not seen contrast sensitivity curves for the enVista, but I suspect it is very similar to the Clareon for contrast sensitivity. It is the Vivity lens that takes the big hit on contrast sensitivity.

Ron, what was the original target set for your distance eye and close eye? are your actual -0.38 & -1.63 very close to the set targets? how much difference is there between target and actual outcome in general?

Sorry for the delay in responding. I have been away on a south vacation.

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The outcomes I got were very very close to what was predicted. It may have been good luck, or perhaps the surgeon was good at choosing the best formula and measurements to use.

hi Ron,

i have heard two patients mentioned they have monofocals set to distance. But after surgery, they cannot see anything clearly from nose to about 6ft, anything after 6ft and out is clear. Do you know why? i thought refraction errors usually caused distance vision more blurry but close up or intermediate might get better (if target is -0.5, actual is -1).

First it is important to understand that individual results vary. The defocus curves that predict visual acuity vs distance are based on averages. Some will show error bars that indicates the range of individual results. That said if the target is accurately achieved for distance vision (-0.00 to -0.50), the large majority of individuals should have good (20/32) down to 2 to 3 feet. 20/20 vision starts at about 6 feet.

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There are some factors which impact near vision. The main one is the outcome refraction. As an example -0.50 D and +0.50 D will give about the same distance visual acuity, probably about 20/25 or so. But, the near vision will be much better with a -0.50 D result. That is the reason why most surgeons target -0.25 D to avoid going positive.

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I have also seen one study which found that being myopic before surgery tends to result in having better near vision after surgery. Also having smaller pupils, which really likely means being older, helps with near vision.

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But, this said I would suggest if vision not clear until 6 feet then the surgeon has likely had a significant miss and left the patient far sighted in the plus side of refraction. These surgeons are likely targeting plano (0.00) instead of mild myopia, or they are using one of the poorer formulas for IOL power calculation.

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One important step in preparing for cataract surgery is to ask to get a copy of the IOL calculation sheet which shows the predicted outcome for each step of IOL power in the range you need. It is highly unlikely that they will be exactly at the target you want. One example might be that one power yields 0.00 D for an outcome, and the next power higher is predicted at -0.375 D. It is tempting to select the power that gives 0.00 D, but I would suggest that is the wrong choice. Much better to select the power that gives -0.375. Distance vision is still likely to be 20/20 and near vision will be better. But, the point is that you should be part of that discussion as there will always be a choice between two powers that could be used.

i have heard two patients mentioned they have monofocals set to distance. But after surgery, they cannot see anything clearly from nose to about 6ft, anything after 6ft and out is clear. Do you know why?

"Clearly" is subjective.

i thought refraction errors usually caused distance vision more blurry but close up or intermediate might get better (if target is -0.5, actual is -1).

What were the prescriptions/refractions of the patients? A prescription consists of Sph, Cyl, and axis for each eye, but only Sph, and Cyl matter for this purpose.

" As an example -0.50 D and +0.50 D will give about the same distance visual acuity, probably about 20/25 or so."

Why would +0.50D not be 20/20 distance vision?

On https://patient.info/forums/discuss/translating-defocus-curves-from-d-to-feet--803594?page=0 see the image on Jimluck's post. Try to understand this defocus curve.

Does your vision get better than 20/20 past plano? I thought +0.25 or more actually hurt your distance vision.

Hyperopia is complicated. With the natural eye we can tolerate some hyperopia and still get 20/20 vision because the lens has accommodation to correct the focus. However, with an IOL as best as I can understand it, is that they have a single best focus point and visual acuity drops off (based on the defocus curve) at about the same rate in each direction. So you lose about the same amount of visual acuity with the same amount of diopter miss in either direction. But at the near distance end of the scale vision gets better with a myopic miss, while it gets worse with a hyperopic miss.

Does your vision get better than 20/20 past plano?

No, as Ron said.

Did you try to look at that defocus curve image? Did you note the horizontal axis? How about the vertical axis?

I looked at your conversion chart axis to feet. For target 0, when moving towards hyperoptic you do not have any feet you simply have far far far, which I interpret to mean unusable vision. With an IOL. if you end up with a +D - it does not do you any good - it will only hurt your near vision. Do I understand this correctly? If I can tolerate mini or micro monvision, I do not want my distance eye to be more than -0.25D. To me, it is all about usable vision. I don't use a defocus curve. I divide a meter 39.37" by diopters to equal inches for best quality vision.

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It is a hard concept that you would lose visual acuity from 20/20 with a +.05D .

Below is a defocus curve for the AcrySof IQ monofocal. A "landing zone" of +0.50 D to -0.50 D is illustrated. At the peak visual acuity is nearly -0.10 (20/15), and at the two extremes of minus and plus 0.5 D it is still 0.0 (20/20). Some surgeons look at his wide area as their goalposts for success. I see it differently. If they hit the +0.50 D goalpost I see that as a major failure compared to -0.50 D. Yes, visual acuity at distance is the same at 20/20, but there is a 1.0 D loss in depth of focus if they hit the +0.5 D post. The whole curve slides over to the left with a +0.5 D miss, whereas it slides to the right with a miss to the myopia side. This makes a big impact on near vision. For these reasons most surgeons will target to -0.25 D as the sweet spot is to the right on the myopic side. But some surgeons where both eyes are targeted for distance may be more cavalier and assume reading glasses will be needed in any case and that whole landing zone is fair game for a target.

Ron, does the IOL calculation sheet contains different calculations with different predicted outcomes from multiple formulas or one formula chosen by surgeon?

for my L eye that has a glasses prescription of -11.5, one surgeon has a 8.0D Alcon Clareon with a predicted outcome of -3.1. is this too close to plano that i might get hyperopic? i read that high myopic patients tend to have more errors in the IOL calculation and errors can be plus or minus 1.0. si wouid it be better to target -1?

that should be +0.5D not +.05D

julie, i looked up Jim's defocus curve and trying to understand how it works.

for target at plano 0D, his curve shows 20/20 vision at infinity and 20/40 at 39". so the patient at plano physicsl will start seeing clearly at 6.5 ft (20/32)?

for a target of -1, patient will see 20/20 at 39", anything past that distance will start getting blurry (6ft is 20/32, infinity is 20/40)?

If you go directly to the various IOL Calculation sites on the internet I believe they only show their own formula calculation results. However, the IOLMaster program that many ophthalmologists use, can handle multiple IOL formulas. If you google this document and look on page 5 your will see an example. This one is displaying 2 formula results; Barrett Universal, and Barrett TK Universal. It looks like there may be room for 4 formulas to be displayed. One would hope the surgeon would set display up to show at least a couple or more of the good ones like the Hill-RBF 3.0, EVO 2.0 and the Barrett Universal. The surgeon or technician selects which formulas they want to display.

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IOLMaster 700 Quick Guide Printing Functions EN PDF

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For sure if a good formula is used a predicted outcome of -3.1 is not too close to plano and a hyperopic outcome would be highly unlikely. But you are going to need glasses to see distance.

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It is something to discuss with the surgeon, but selecting a target of -1.50 D for the non-dominant eye may be a good strategy for the first eye. Then that could be refined for the second eye with a target of -0.25 D to get better distance. It is a decision you could make after the first eye has healed.

With an IOL. if you end up with a +D - it does not do you any good - it will only hurt your near vision. Do I understand this correctly?

You understand correctly.

If I can tolerate mini or micro monvision, I do not want my distance eye to be more than -0.25D.

Zero, or plano would be very good. Would -0.25D be better, because you will get sharper vision at maybe the 80 inch or so distance? Maybe.

I don't use a defocus curve. I divide a meter 39.37" by diopters to equal inches for best quality vision.

40 inches will make it easier if doing some stuff in your head.

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It is a hard concept that you would lose visual acuity from 20/20 with a +.05D .

A bit, but you may have meant +0.5D.

sorry, i meant to type the predicted outcome as -0.31, not -3.1!

Hi Trilemma,

I looked up Jim's defocus curve and trying to understand how it works.

for target at plano 0D, his curve shows 20/20 vision at infinity and 20/40 at 39". so the patient at plano physically will start seeing clearly at 6.5 ft (20/32)?

for a target of -1, patient will see 20/20 at 39", anything past that distance will start getting slight blurry (6ft is 20/32, infinity is 20/40)?

OK, -0.31 is fine for a target to get distance vision for most people. However, with your very high myopia it may be cutting it a bit too close to plano. The strategy will depend on your objective. Here are my thoughts for two different objectives.

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Distance vision both eyes, OTC readers for close vision:

I would target the eye with poorer vision to -0.50 D, and then with the learnings from the outcome at 5 weeks, target the second eye closer to plano at about -0.25 D.

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Mini-Monovision hopefully eyeglasses free for most activities:

I think I would target the non dominant eye for -1.50 D to be the reading eye. Then with the learnings from that eye at 5 weeks then target the second eye to -0.25 D.

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It would be important to use a formula that is suitable for high amounts of myopia like the Hill-RBF 3.0 D. With the learnings from the first eye the surgeon should be more accurate on the second eye.

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Keep in mind that progressives are always a good solution if there is a miss on the targets. All you are really doing is determining what your vision will be like without glasses. Either way you go or even with a significant miss by the surgeon you will still get good vision with progressive glasses. That is always a plan B backup.

Ron, I have looked at page 5 for an example of a calculation print out. I notice there are two formulas used -- Barret TK abd Barret Universal. However one if for Keratomy and another is total Keratomy. what's the difference between keratomy and total keratomy?

for the different formulas, I also notice that with the same predicted outcome, the IOL power can differ by 1.0D. That seems like a big difference! How and which do we or surgeon select?

The IOLMaster 700 model does total keratomy (TK) measurements which means it measures the shape of the both the inside and outside of the cornea layer. The older 500 model I believe does not do this. From what I understand using TK is most useful in patients that have had prior laser surgery on the cornea. And the TK formula may not be an option if your measurements came from the model 500 instrument.

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I am not sure how realistic the data in that example is, and whether or not they are from a real patient or are just made up. The differences are even more substantial in the toric calculations a couple of pages later in the document. Perhaps they were just trying to show off the benefits of doing TK in a more difficult case possibly with prior laser surgery. Don't know.

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My brother had his measurements taken with an IOLMaster 700 and the surgeon used the Barrett TK formula. I have a copy of the calculation sheet and have compared the results to other formulas including the Hill-RBF 3.0. He got a good result but I think the Hill formula would have given him a slightly better outcome with a lens power 0.5 D different from the one he got. He ended up hyperopic with his astigmatism bringing him back to near plano. The Hill formula would have left him closer to plano with the astigmatism bringing him slightly myopic, which I think would have given him about the same distance vision but slightly better near vision. The interesting part is that he has measurements for both eyes, but has only had surgery on one eye as the other only has a very minimal cataract. In that eye the Barrett TK formula is giving a significantly different prediction than the Hill formula. I recall it is two power steps different. It will be interesting to see what the final outcome will be when he does get surgery.

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I would ask to see the Hill-RFB 3.0 calculations if they have them installed on their IOLMaster. If not then they/you would have to use the on line Hill calculator.

looked up Jim's defocus curve and trying to understand how it works.

for target at plano 0D, his curve shows 20/20 vision at infinity and 20/40 at 39". so the patient at plano physically will start seeing clearly at 6.5 ft (20/32)?

for a target of -1, patient will see 20/20 at 39", anything past that distance will start getting slight blurry (6ft is 20/32, infinity is 20/40)?

Sounds about right. Note that 20/40 is where they draw the limit for your driving eye test. A bit scary IMO.

Not under discussion here, but IMO when you have defocus curves for two different lenses, they are suspect. I suspect that for a good straight single vision lens, the peak should maybe be closer to 20/15. But often they seem normalized to show 20/20 at the peak. When you get an EDOF (extended depth of focus) lens, there is a tradeoff (reduced peak acuity). The curves posted by the maker often seem to be concealing that. But the point of our discussion here is what is the impact of different focus and using that to select targets. You are certainly understanding it.

Thank you. I do understand what you are saying. When I started reading the Forum I did not understand defocus curves and I still don't. It is very difficult for me to understand +.50D is visual acuity 6.5' farther than infinity. I made a spreadsheet that I use - with diopters and visual acuity in inches with difference in inches between diopters - trying to understand EDoF. It probable does not make sense because it is not scientific. I can find the spreadsheet on my computer using one of the icons on this menu - but I am not able to insert it. I think I need to convert to a pdf then to a jpg.

was your brother high myope before surgery? does he feel nauseated with being hyperopic after surgery?

the first surgeon used Barett universal saying he thinks this formula is more precise. i am still awaiting measurement by the second surgeon so not sure which formulas he would use. is the Hill-RFB 3.0 more precise for high myopes?

"It is very difficult for me to understand +.50D is visual acuity 6.5' farther than infinity."

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There is no such thing as being 6.5' further than infinity. Infinity is infinity.

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My understanding of how defocus curves are derived is that you measure the visual acuity of an eye that has perfectly corrected vision for distance (infinity) logMar 0.0 to -0.1, with the IOL lens that your are developing the curve for. Then you put lenses in steps from quite positive to negative powers in diopters in front of the eye, and measure the visual acuity. The diopter power forms the horizontal scale on the graph, and the visual acuity the vertical scale. Vision gets worse as you move away from the 0.00 diopter position both in the positive and negative directions. That is why the defocus curve is bell shaped. It just tells you how vision drops off on either side of the peak visibility point.

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Now if you put that lens in an eye but with the wrong power to get peak vision at infinity then the whole curve moves right or left. If the diopter error is to the negative side the peak vision moves closer, but the vision at distance suffers in accordance with the curve. If the peak is to the positive side then the best vision is at a distance beyond infinity which does not exist and is not useful. You just simply lose vision at distance and you also lose vision at closer distances because the whole curve slides over toward the positive side.

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The impact of targeting lenses to the negative side (which is common) is not often illustrated, but it is done. Curves off to the left positive side are simply a miss, and are never done intentionally.

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If you look at some of the defocus curves shown by the Cataract Coach you will find ones where the curves are offset to show negative targets for peak vision.

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Manufacturers typical do not show these defocus curves offset to the negative side which is what you do with monovision. What they like to show are curves of EDOF lenses which are flatter to the negative side, or multifocal lenses which are flatter still to give better near vision. But in most cases they still illustrate them with the peak at infinity (0.0 D).

Hope that helps, and does not make things more confusing. The short answer is that you cannot calculate distance off to the positive side of 0.0 on a defocus curve as it is beyond infinity which does not exist.

My brother was in the -4.0 to -5.0 D range, so not real high. Yes, the Hill-RBF 3.0 is accurate for higher myopes. This formula has been developed using artificial intelligence with the results of thousands of actual surgeries.

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The Hill, EVO, and Barrett formulas are all on line. You can run them yourself if you ask for a copy of the IOLMaster measurements. They will be on the IOL calculation sheet.

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https://patient.info/forums/discuss/iol-power-calculation-formulas-805028

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If you are interested you can watch the video on how the Hill formula was derived. Google this to find it.

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YouTube Warren E. Hill Introducing Hill-RBF 3.0: Improving Refractive Outcomes

Sorry I didn't answer your question about my brother feeling nauseated with being hyperopic after surgery. The short answer is that he did not mention it. And he was not really very hyperopic. Also well before cataracts he was not all that myopic in the eye that now has had surgery. He was at S -2.25, C -0.75, SE -2.625. His other eye was at -4.5 SE but has not been operated yet. In any case here were the predictions for the +15.0 D power lens (B+L enVista) that was used and the actual outcome:

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Formula, Power, Sphere, Cylinder, SE

Barrett TK, +15.0, -0.17 D, +0.31 D, -0.01 D

Kane, +15.0, --, --, +.08 D

Barrett UII, +15.0, --, --, +0.02 D

Hill 3.0, +15.0, --, --, +0.12

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Actual refraction:

Sphere, Cylinder, SE

+0.25, -0.50, 0.00

The surgeon used the Barrett TK with a target of 0.00 D. So essentially it was bang on. I think the mistake he made was not targeting -0.25 D. If he had I suspect all the formulas would have recommended the +15.5 D power. The outcome would have likely reduced the sphere to 0.00 (not hyperopic) and with the same cylinder the SE would have been -0.25 D. This would have resulted in slightly better near vision with only a very slight impact on distance vision.

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But, this is all kind of splitting hairs, as all the formulas would have predicted the same power. I think the only mistake was not setting the target at -0.25 D.

thanks for the numbers. it looks like all formulas are very close in their prediction. yes i agreed with you that is target used was -0.25, the predicted outcome will all be a touch myopic.

in your numbers, " -- " means zero or cannot be calculated?

also what does SE mean and how to calculate for that?

The surgeon used the Barrett TK toric calculator with a zero cylinder correction, and with that method it gives a prediction for both sphere and cylinder. With the other methods I did not use the toric versions, and when you do that there is no prediction of sphere and cylinder, only a spherical equivalent or SE number. That is the combined estimate of sphere and cylinder and is calculated by adding 50% of the cylinder to the sphere diopters.