Post-operative follow-up, eye exam and astigmatism

RandallG

Thank you for the quick response.

It seems that I will only have one follow-up in 8 days, so I have no choice but to wait and hope that nothing serious happens in the meantime.

I am sure that if you have serious/worrisome symptoms/pain, which is VERY UNLIKELY, they will see you ASAP.

Frankly, my first check-in the next day was a bit of a waste of time.

The dr looked at it a minute or so, said "looks good" see you in another week.

I'm sure you'll be fine.

As far as checking on how well you hit target, as mentioned before, it takes time for things to settle down and everyone is different. My first two weeks were a BLUR—literally 😃. The dr. said to give it time and now I am very happy with the result.

Best wishes!

Thanks for the encouraging words.

I've been through a couple of surgeries before but somehow even thinking about this one is making me anxious I'll try to stay positive and not worry too much (if I can help it).

Good to know that your blurry vision after the surgery wasn't something serious and you are happy with the results.

Thank you for the response, informative as usual.

You are right, my mistake. Here's what I meant:

LE: Tecnis 1, target at -.25 D

RE: Tecnis Eyhance, target at -1.0 D

I know about your choice and I even mentioned that I would consider such targets but she disagreed even with -1.0 D for my near eye and decided on RE -.75 D which is more micro-monovision. Maybe she considered -.75 D for my right eye because my priority is having almost perfect distance.

To be honest, I'm frustrated and worried since I only got the chance to see the surgeon for less than a minute to ask one question. Post-up visits also will be with his assistants. It appears that he is very busy between his private practice, hospital and U of T. I'm not even sure that he would do the surgery himself as most hospitals are part of the University Health Network and common surgeries are done by residents supervised by surgeons (such phrase mentioned on the consent).

I'm glad that I got 5 weeks between surgeries and you assured me that it would be good enough to get a reasonably accurate measurement before my second eye surgery.

Regarding astigmatism, I looked at my IOLMaster sheet and I believe you confirmed my guess that what I was told is calculated residual value. Even though I'm a technical person but I don't much understand these calculations.

At this point, I'm just hoping for the best as it's too late to get into another waiting list even though my waiting time is less than two months due to my poor vision caused by cataract.

Well -0.75 D with the Eyhance should certainly give you good car dash vision. Where it will become a little iffy is reading a smart phone or smaller printed text. I am at -1.6 D SE in my near eye and my limit is the unit pricing signs at the grocery stores. They like to make these small so you won't look at them. But, I can still read them except perhaps for the lowest shelf. I would have to lie on the floor to read those ones! My suspicion with the -0.75 D target is that you may be reaching for readers fairly often.

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I would still ask them for a printout or PDF of you IOL Calculation sheet. It is really all you have for evidence as to what outcome you should get with the selected IOL power. If you google this there is an explaination as to what the readings mean. The critical part is the tabular list of potential lens powers that could be used and what the predicted outcome of each is. With non toric lenses those outcomes are in SE units. See page 5 & 6 for a non toric example.

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IOLMaster 700 Quick Guide Printing Functions EN PDF

Thanks for the additional information.

I have a printout of my IOL calculation sheet but I noticed they used +0.00 (Plano) for my LE and -.75 for my RE in the calculation, so the outcomes are not exactly based on what I requested. I insisted on having an appointment before the first surgery (set for Tuesday) to ask my questions and confirm the numbers one more time.

The good thing is that I have enough time between surgeries and I plan to go with -1.00 D for my near eye if the surgeon can hit the target of -.25 D for my LE.

When targeting for distance surgeons have different styles. On the IOL sheet you are likely looking at the "Target ref" value they have used. Some will put plano or 0.0 in that field. Then the computer will find the lens power that gives a predicted outcome closest to that value. It may be slightly negative or slightly positive. But, there is no upside to going positive (far sighted) as that reduces your visual acuity at distance, but reduces it more at closer distances. For that reason if they enter plano, they will not likely select the lens power that the computer highlights as the best fit. They will manually choose the next power that goes one step more negative. That is a factor of safety against going positive.

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The other method is to target -0.25 D. Again it is highly unlikely that one of the available powers and they will likely give you two choices with one more and one less than the desired -0.25 D. It becomes somewhat of a judgement call as to which one to select. But you really don't want one that is real close to 0.0 D for fear of going positive. This method should give the same lens choices with the same outcomes. The only difference is the computer will highlight the one closest to the -0.25 D, instead of plano.

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The end result of the this exercise is to pick the power you are going to go with, and you really should be part of that decision. It will almost always come down to a choice between two lens powers 0.5 D apart. The point is that choosing your target does not mean you will get that outcome. It just lets the computer show you what the predictions are for each lens power available that are close to your target. The surgeon and ideally you should manually pick the best one.

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Since you have the IOL Calculation sheet all the data on your eye measurements should be there to allow you to do your own calculation of IOL power. Probably the most accurate calculator available today is AI based and is called the Hill-RBF Calculator Version 3.0. You should be able to find it online and enter your own data to see what it says compared to what the surgeon is predicting. It may be that your surgeon is using this same calculator. Our surgeon is university prof at the UofA and he used the Hill RBF and got very accurate results with our eyes. Either way you can enter different targets and see what the predictions are. The Barrett Universal II is also on line and is probably the second best for accuracy. So, you can run it too with your eye measurements. It is actually not that hard. The only complication that I ran into doing this is that some browsers do not play well with one of these formulas. If you have issues try a different browser. With one of them I think I had to switch from Chrome to Edge to get it to do the calculation.

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Hope that helps some. They key point here is that it is not the exact target they pick, it is the lens power they pick that predicts what your outcome is likely to be. Setting a target is to just get you into the ballpark with the potential lens powers.

Regarding the accuracy of IOL power calculations, a 2023 article in the Journal of Refractive Surgery reviews the accuracy of 24 formulae. Oleksiy Voytsekhivskyy, et al., "Accuracy of 24 IOL Power Calculation Methods", J Refract Surg. 2023;39(4):249-256. The patients all were examined at the Kyiv Clinical

Ophthalmology Hospital Eye Microsurgery Center, and presumably for that reason the authors note that all were white. All patients were implanted with the monofocal Tecnis 1 ZCB00, thus eliminating IOL variation as a potential confounder.

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Before providing the study's conclusions, I should note that the predictive accuracy of any IOL power calculation formula depends on the so-called constant used in running calculations. Each IOL manufacturer will provide its own recommended constaqnt or constants for its different IOLs. But surgeons are encouraged to develop and continuously review their own personal constants by comparing their refractive results to the predicted results. Unless you know your surgeon's choice of formula and constant, running your biometric data through an online power calculator is of limited utility.

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An analogy to timber estimator error from a long ago class in managerial decision-making under conditions of uncertainty at Harvard Business School may help illustrate the point of the preceding paragraph. We learned from a case study that the inaccuracy of estimates of the amount of harvestable timber obtainable from a particular area didn't matter so long as the the error was consistent because then the timber estimator's error factor could be used to adjust the estimate to get an accurate result. As a loose, but I think helpful, analogy, you can view the surgeon's constant as the adjustment factor aplied to the power calculation formula to improve predictive accuracy.

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As between the Barrett Universal II and RBF 3.0 formulae, I read the study as concluding that they're both very good, and more accurate than older formulae. The study also reports some differences depending on axial length: "In the short AL subgroup (n = 27, Table B), the best results were achieved with the Hoffer QST (MedAE = 0.305 D), Castrop (MedAE = 0.306 D), and VRF-G formula (MedAE = 0.315 D) and the worst result was produced by the Panacea (MedAE = 0.695 D) formula. In the medium AL subgroup (n = 190, Table C), the VRF-G, BUII, and RBF 3.0 formulas demonstrated the highest accuracy (MedAE = 0.199, 0.226, and 0.227 D, respectively) and the lowest accuracy was shown by the Holladay 2 formula (MedAE = 0.300 D). In the medium-long AL subgroup (n = 58, Table D), the highest accuracy was achieved with the RBF 3.0 formula (MedAE = 0.156 D) and the worst with the Hoffer Q formula (MedAE = 0.302 D). The VRF-G (MedAE = 0.161 D) and VRF (MedAE = 0.164 D) formulas ranked second and third in this subgroup. In the long AL subgroup (n = 25, Table E), the best results were from the Castrop (MedAE = 0.124 D), Olsen (standalone) (MedAE = 0.128 D), and EVO 2.0 (MedAE = 0.138 D) formulas, and the worst result was from the Holladay 1 formula (MedAE = 0.541 D)."

I know about "IOLMaster 700 Quick Guide Printing Functions EN" file as you have already mentioned in some of your posts. In fact, I used it as a reference when I got my IOL Calculation Sheet which is based on the Barrett Universal II formula.

In my IOL calculation sheet for ZCB00, the highlighted predicted outcome with Target ref of 0.00 (plano) is +21.50 +0.09 D and one line above that is +22.00 -.25 D which is not highlighted. of course I would like to go with the outcome of -.25 D but my concern is that I won't get the chance to discuss the choices with the surgeon before the surgery geon and I end up in the positive range, considering that there is always the possibility of ±.5 D error on top of the fact that every eye is different.

Thanks.

Thank you. Interesting article!

Sounds encouraging as in my case the Barrett Universal II formula is used in my IOL calculation which is among the more accurate ones (SD ±0.405 D).

Yes, for sure you would want the +22.0 D lens over the +21.5 lens based on the Barrett formula. I would not agree to having the surgery done without an agreement with the surgeon as to exactly what power lens will be used. They have to give you a card with the serial number, model number, and power of the lens they used, so you are not asking them for something that is a secret. You are just asking them to tell you ahead of time.

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It would be well worth your while to enter your data into the Hill-RBF 3.0 formula to see what it says. If it also says +22.0 is the best choice then I would feel pretty confident that is the one to go with. But, yes as you say it is not a perfect process and there is always some risk. Some will target -0.5 D, but that is starting to compromise distance vision, and would not be my choice. If you need any help using the Hill formula just ask. I have done it a few times.

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What I find interesting about the Hill-RBF formula is that it uses artificial intelligence and is constantly being refined. The 3.0 version is newer than the Barrett Universal II which is a theoretical formula instead of being AI based. Dr. Hill asks surgeons to feed him patient data and outcomes to update the AI based formula. There is an interesting (but not short) YouTube video by Dr. Hill on the formula that is interesting to watch if you want to take a deeper dive. Google this:

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YouTube Introducing Hill-RBF 3.0: Improving Refractive Outcomes

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It would also be very helpful to have a face to face discussion with the surgeon. The very blunt question to ask is how confident are you in hitting this target? They will be evasive with lots of CYA talk but you should get a feeling as to how confident they really are.

As you suggested, I entered my current data from Barrett Universal II into Hill-RBF Calculator. Pic1 is the result for Target ref of 0.00 for my LE.

In both formulas, the lens power on the highlighted lines is the same with slightly different outcomes:

Barrett Universal II: +21.50 +0.09 D

Hill-RBF: +21.50 +0.09 D

But if I choose +22.00, the outcome in both formulas, the comes would be closer to what I want.

Barrett Universal II: +22.00 -.25 D

Hill-RBF: +22.00 -.37 D

For my RE, I'll decide after the surgery on my LE.

You mentioned that they are supposed to give me a card with the lens information. Is it before or after the surgery?

Thanks.

I tried to attach the image of the calculation results but the whole reply went on waiting so I'm just posting the text part of my reply.

This sure looks like the +22.0 D power is the right choice. I would strongly resist them putting in the +21.5 D lens. You do not want to go positive. In my wife and my case we got our IOL card right after the surgery. I expect it comes with the IOL lens so they have it right there during the surgery and give it to you after.

What A-Constant did you use? I recall that the original value from J&J was 119.3, but someone here posted that it had been revised to 119.39. Not sure where their source was. I recall that the impact was fairly minor when changing between the two values. Also sometimes surgeons will change this A-Constant to reflect their personal outcomes with the lens.

The A-Constant I used is 119.34 which I got from the "LENS CONSTANTS" tab on the Hill-RBF Calculator website. 119.39 does not even exist in the table.

I feel more confident with my choice now and I intend to confirm it on Tuesday before my Thursday surgery. It's unlikely though that I get a chance to discuss my lens power with the surgeon ahead of the surgery but at least it would be in my file.

Thank you for the replies. Helpful as usual!

I suspect the reality is that the 5th significant digit is not really significant.

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I think I would insist that the surgeon confirm what power of lens is going to be used, or I would cancel the appointment. That would be super ignorant of the surgeon to not even confirm the power selection. Unless we get into lens exchange which does not always go well, we only get one chance at getting things right.

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While my surgeon did actually get things mostly right in the end, he was not very cooperative on the road to get there. For that reason I cannot recommend him to others. Bedside manner was very poor. I think these guys come to thinking that if the total cost is being covered by healthcare or insurance they do not have to be respectful to patients and think it is their right to exclude them.

I can't agree with you more. That's exactly how I felt in my consultation. Waited for two hours, literally being rushed, somewhat ignored and in the end, I was seen by the surgent's assistant. They even seemed irritated by my questions. And, when I asked for an appointment before the surgery, I was told that all my questions have been already answered, why would I need another appointment.

In fact, I learned 10 times more from this forum than from the doctors I talked to. I don't know what outcome I will end up with but I'm glad that I found this site and did my homework.

Unfortunately, that seems to happen fairly often to patients, both in Canada and in the USA. Although here in the USA, patients have more freedom to "shop around" and choose their cataract surgeon. It really affects all branches of medicine. I went to a dermatologist last week for a head to toe skin exam and my doctor was trying to finish with me as quickly as she could. There are more people, particularly Baby Boomers like myself, seeking medical care than ever before.

I would just bluntly say you cannot give consent for the surgery until you see the specific power of lens to be used and what the predicted outcome will be. If they try to blow you off by pointing to the IOL Calculation printout, just respond that it says the target is plano and that is not what you want.

I live in Manitoba and had the same experience. I was initially told it would be over a year to get my initial appointment, so I started doing my research. The province ended up allowing ophthalmologists to do more surgeries so I ended up not waiting that long. However, I was just given the basic information and was not told what target they would be shooting for. I too had to argue with the staff to get a second appointment for more information. If it were not for this forum I wouldn't have had a clue. I asked for the IOL calculation sheet and did my own calculations with Ron's help and then felt confident going into surgery that what the doctor picked is what I wanted. On the day of each surgery I even confirmed what power of lens they were giving me. Mistakes happen and I just wanted to make sure. I was fortunate in that my optometrist sent me to one of the top ophthalmologists in my province and he was very good at what he did. In all fairness to the ophthalmologists though, they are very busy and most people don't want to know what they are getting or why. They just want it done and to be on their way. For those of us who do want to know and want to have a say, it is an unusual situation for the doctor.

Karin, what was the name of your surgeon? My brother is in Manitoba and has only had one eye done, and now his surgeon has moved to Toronto. I wouldn't mind passing the name on to him.

His name is dr gdih and he is at aqua i laser in Winnipeg. My understanding is that he only uses J&J, so not sure if that is what your brother would want.

Ok thank you. I will pass it on. He got enVista in his first eye by Dr. Rocha. But he has moved on.

Thank you for sharing your experience, Karin.

My optometrist referred me to two private clinics and one in healthcare that didn't have an above average track record. I did the rest of my consultations through my own research. I waited about four months for my initial consultation in one of the hospitals that is part of the UHN (Universal Health Network) but the surgery was scheduled in less than two months due to my poor vision affected by cataract.

As I mentioned in my previous posts, my initial consultation was supposed to be with the surgeon but I ended up being seen by his assistant and to be fair she was nice and addressed some of my concerns. Hopefully, I'll get to confirm and clarify my intended power of lens and the predicted outcome on Tuesday ahead of my surgery to regain some confidence in my upcoming procedure.

Agree with you Lynda. That's the unpleasant truth that gradually becomes the norm in medical practice.

We can also choose our cataract surgeon in Canada but most well-known surgeons practice in private clinics and the good ones in our health care system require a very long waiting time. So eIther you have to go with the high cost of private clinics or settle with what you can get through the Healthcare system.

That's my plan to confirm and clarify all that and make sure everything is in place before the surgery.

Thanks

Hope your surgery went well. We were out camping without internet service, or even electrical power.

Hi Ron,

It's tomorrow (Thursday) morning. Just to let you know I got the chance to discuss my concerns with the surgeon on my Tuesday appointment.

I'll post an update in a few days. Enjoy your outdoor camping!

Thanks