my surgeon suggessted the Alcon Clareon monofocals set for distance for my L eye. i am highly myopic with glasses Rx -11. How close will I see with this IOL? some people told me 6 ft and under will be blurry but some said 3 ft and under. i am confused! help!
I have the AcrySof IQ monofocal lens set for distance vision with an outcome of 0.00 D sphere and -0.75 D cylinder. This AcrySof IQ lens is optically identical to the Clareon lens. This outcome converts to a spherical equivalent of -0.375 D, or very slightly near sighted. I can still read my computer monitor with this eye at 18-20", while having 20/20 vision at distance. The clarity is not great at this close distance, but I can still make out the letters. I can easily read the instruments on my car dash. This seems to be better than some people get. This probably is due to me being older with smaller pupils, and the astigmatism (cylinder) giving me a bit more near vision. Also the cylinder is against the rule at 90 deg axis, which I understand helps as well with near vision. . A reasonable expectation would be to see reasonably well down to 2-3 feet. Each person will be a bit different. Being myopic before surgery can mean being able to see closer, as well as having a smaller pupil, typical of an older person, can be helpful in getting a better near vision outcome. . What you want the surgeon to do is target slight myopia at about -0.25 D to get good distance vision, plus closer near vision. . Incidentally I have the Clareon lens in my other eye with an outcome of -1.60 D SE, and between the two eyes, I am essentially eyeglasses free.
The short answer is no one can say. Every case is different. Some lucky people end up being able to read within 18-24". Some can't read anything closer than 36". It's certain,y not 6 feet though. I think usable vision down to 36" is a very safe bet for almost everyone to achieve and maybe a little better. Also bear in mind that it's a gradient not a binary. It's not like 37" is crystal clear and 35" is a total blur. You can see and read at less than 20/20. The general rule is that usable vision starts at about 20/40. So if you have 20/40 at 2 feet you might be surprised at how well you can function at that range in good light. That's another thing that people always forget to mention. Light is KEY! I can actually read J1 with my Eyhance set for distance (i.e. small print at 14"… a very unusual result) BUT ONLY in bright sunlight. As the light gets dimmer the near vision I was lucky enough to get drops off very fast.
LogMAR 0.0 is about the same as 20/20 vision. LogMAR 0.30 is about the same as 20/40 vision.
If you find a defocus curve, typical the peak will be at LogMAR 0.0.
Then see how many diopters correspond to 20/40 or LogMAR 0.30. Take the reciprocal (divide 1 by the diopters). That would be the distance in meters where you would expect 20/40.
20/40 is what would pass your driver's licensee vision test.
There have been some wonderful links that illustrate this, but I don't know where I put them.
I can actually read J1 with my Eyhance set for distance (i.e. small print at 14"… a very unusual result)
That very unusual . My Ehyance set at distance struggle with J8.
Yes I was shocked too. I got very lucky I guess. I do have -0.75D of astigmatism helping me out. And again it requires very good lighting (like direct sun is best). But I can read it. Can read my Phone / iPad as well starting at about 10-12" away. Bit that is very atypical. The final refraction for that eye was +0.25 Sphere, -0.75 Cylinder @ 168° Axis.
What does your doctor recommend for your right eye?
What distance is most important to you to be glasses free?
I'm very myopic. I would not choose long distance to be my glasses-free range. But that's a question of personal preference.
my surgeon said will target for -0.2D for distance. Is that good? how precise is this target? i don't want to end up hyperopic!
i do have -0.75 astigmatism which the surgeon said i dont need a toric IOL. hiw do i know my astigmatism is against the rule? what does it mean by "against the rule"? why would having some astigmatism help with improving closer range of vision?
thanks!
Yes, in nominal terms -0.25 D is a good target for distance vision with an IOL. However, that said, there is no way for an ophthalmologist to dial in a -0.25 D outcome. The IOL powers come in 0.5 D steps and what they actually do is set a nominal target, and then see what the available IOL powers in that range will actually produce based on the IOL calculation formula. So what they will see is a column of power choices with a predicted outcome for each. If the nominal target is -0.25 D then there will likely be one power that will be above that, and one power below. They ideally with your input will have to decide to go with the one higher or lower. Or you could win the lottery and one power will be exactly -0.25 D. So, perhaps what your surgeon is saying is that their prediction for a certain power that they are planning to use is -0.20 D. That is very close to the nominal -0.25 D, and that is a good choice. . Normally when the predicted astigmatism is less than -0.75 D then a toric is not warranted. When the astigmatism is in optometrist format with negative cylinder my understanding is that against the rule is when the axis is around 90 degrees. With the rule is around 0 deg or 180 deg. With the rule is more common in younger people, and against the rule more common in the elderly. . Think about sphere being the basic power with -1.50 giving good near vision. When you have -0.75 D cylinder (astigmatism) part of the eye is actually at -2.25 D (the sum of the two. That gives you nearer vision, but also with less visual acuity.
hi Ron,
so the target my surgeon will dial in -0.20 D can be used for a high myope? i am highly myopic with L eye -11.5 and R eye -10.5. if he chooses the one power above -0.20D, that means i will have a bit more than -0.20D myopic (maybe -0.3 or higher)?
does against the rule or with the rule astigmatism affect cataract surgery outcome?
if after surgery, my residue myopia is -0.50 D , with a -0.75 astigmatism, is it like a power of myopia of -1.25 D so I might see intermediate better?
your final refraction of +0.25 means you became hyperopia? were you far-sighted before surgery? i heard if you were short-sighted and became hyperopia, it can be extremely uncomfortable even though i dont know what the uncomfortable means!
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.
Yes, that target is still ok with high myopia. Your myopia is quite high, and that would require a fairly low power IOL. A rough rule of thumb calculation would be in the range of a +4.0 D lens. That may be a problem as at least early on, the lowest power the Clareon was initially available in, was +6.0 D. However, if your surgeon has already measured your eyes and is recommending it, then there must be a suitable power available. It would be worth asking what power of lenses are available. Sometimes when you get to the extremes of the lens power range the steps between sizes increases from 0.5 D to 1.0 D. That would make smaller adjustments more difficult. . When you choose a higher power than what is needed for plano vision then you leave some more of the myopia. And if -0.20 D is possible, and you choose an IOL with 0.5 D higher power that will bring the residual to about -0.50 D, which if you are really afraid of going positive or far sighted, it is an option. It puts 20/20 distance vision at risk though. . There are some IOL Calculation formulas that are more suitable for high myopes, and I would hope the surgeon would use them. Another option to consider is using a surgeon that has the Alcon ORA intraoperative aberrometer system. They measure your eye again during the cataract surgery, after your natural lens is removed, but before the IOL is inserted. They make the final lens power choice at that time. I believe it is fairly expensive add on option, but may make sense in your case if your objective is to be eyeglasses free after surgery. If that is not a priority, and you are willing to wear glasses then a more accurate correction is not essential. One contributor here was highly myopic and had the ORA system and got a very accurate outcome. Another I recall used it and there was a miss. So YMMV. It may be worth discussing with the surgeon if they offer it. . With or against the rule astigmatism does not really affect the outcome. Some surgeons choose the incision location to minimize the surgery induced astigmatism, and it may be a minor consideration. But, beyond that there is not much they can do differently. . IOL Power calculation predictions are done on a spherical equivalent basis. That is (when astigmatism is reported as negative) the sphere plus 50% of the astigmatism. So, in your example of -0.5 D sphere and -0.75 D cylinder that works out to be -0.875 D, or about -0.9 D. Nearer vision will be better due to the more myopic spherical equivalent, but perhaps not as sharp. My distance eye was targeted to be about -0.3 D SE, and ended up at 0.0 D sphere, and -0.50 D cylinder for a SE of -0.25 D, pretty much right on target. However, on my last vision check my astigmatism had increased to -0.75 D with sphere remaining at 0.0 D. So I am no at about -0.375. My near vision is pretty good. I can see very well down to 2 feet and with a computer monitor I can still read normal size text at 18". But, individuals vary on what they get with near vision. A more typical expectation would be 2-3 feet. . Hope that helps some
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.
ORA is not an option for my surgeon. unfortunate! but my cataract is a 2+ and they said its mild, so i am guessing they can get my eye length measurement quite accurately?
i thought the power of the IOL should have similar number as my myopic rx but with the opoosite sign? for example, my L eye is -11.5 so i would need a + 11.5 IOL?
how accurate is the formular to calculate the correct IOL power? according to my surgeon, he said quite precise. But i will have a pre-op with him to finalize the details of the IOL and power in Dec.
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.
Ron, since you have arysoft in one eye and clareon in the other, are they any different? how much do you know about dysphotosia from these IOL? i heard minimal people still complain about positive dysphotosia with monofocals, so i am worried even choosing monofocals, dysphotosia still happens!
The old formula that I used to make the rule of thumb estimate is to take your pre-cataract eye prescription for sphere multiplied by 1.25 and then add it, respecting signs to +18 D to get your IOL power. So for a -11.0 D prescription for sphere the calculation would be as follows. The cataract may have changed your prescription, so you could possibly get some better accuracy if you can find what your eyeglass prescriptions were a year or so before cataracts started to appear. . (-11.0 * 1.25) + 18.0 = +4.25 . Keep in mind this is a very crude formula used in the 1970's before today's advanced measurement instruments and computerized formulas. There can be a lot of error in this old rule of thumb formula, and it would never be used today. Google this for some information on it: . Dr. Hill IOL Power Calculation formulas . Dr. Hill is the originator of the Hill-RBF 3.0 formula which is based on AI and is considered one of the best. You should ask your surgeon to show you the predictions for your power need based on this Hill formula and the Barrett Universal II. They are two of the best for high myopes (long eyes). The Hill formula will issue warnings if it considers your power is out of the range that it is accurate in. . This said if the rule of thumb is in the ballpark you may have issues getting a Clareon lens that low in power. Alcon makes some AcrySof lenses however that actually go into the minus power range, but they come in 1.0 D steps instead of 0.5 D steps. AcrySof is optically identical to the Clareon lenses.
The prime difference between the Clareon and AcrySof IQ is the new material used in the Clareon that is claimed to be much more resistant to the formation of glistenings. It also is said to have a higher light transmittance - possibly the source of the Clareon name. It also has sharper edges which is supposed to make it more resistant to PCO. . My experience is that I essentially see no difference in clarity or optical side effects like dysphotopsia. With very specific conditions of near total darkness and a point light source off to the side, I do see some arc shaped flashes in my peripheral vision with both lenses. I suspect it is reflections off the edge of the lenses when my pupils are wide open. That said it is more of a curiosity than a problem. I almost never see them, but they do happen. . Interestingly with respect to PCO my optometrist is now telling me that he sees some in the Clareon eye (which is supposed to be more resistant to it) which has been in for about 18 months now. I don't see it though. He says he sees nothing in the AcrySof eye which has been in for about 3 years. He is suggesting I consider YAG in the Clareon eye. Will be getting a second opinion on it later this month.