Monofocal lens set for near vision
Posted , 11 users are following.
hi guys. im curious as to why i never hear of people getting a monofocal vision set for near instead of for far. for myopes, the pleasure of not needing glasses to drive etc would perhaps be outweighed by having less of an adjustment to just put glasses on to see for intermediate and far, as we all have been doing that for as long as we had myopia. is there a down side to getting a close monofocal lens? thoughts?
also, for those who have gotten monofocal implants set for far distance, at about what distance from your eyes does your vision begin to get blurry as you get nearer something?
thanx much. trying to amass info for the future
dan
1 like, 86 replies
thomas84367 Dapperdan7
Edited
Most cataract surgeons seem to have a bias against setting both eyes for near. They prefer a monovision approach for patients that wish to retain some degree of near vision.
I believe that's because people like us who do our homework, ask a lot of questions, and are capable of making informed decisions when it comes to cataract surgery are few and far between. I think most patients have no clue, so the surgeon is going to recommend the best option based on their individual experience with patient satisfaction.
So my take is that the only reason there aren't more patients who choose to target intermediate or near is because those patients who do so tend to be far better informed and more self aware than the average cataract patient.
Even within that pool of informed patients,, I think setting both eyes for distance or taking a monovision approach would still be the most popular option, but the numbers wouldn't be as skewed as they are in comparison to the general population..
Dapperdan7 thomas84367
Posted
hey thomas. great post. it boggles my mind that people would NOT do their homework with their most precious sense: vision. i have been doing my due diligence for awhile. one thing i have learned in seeing several optometrists is a lack of patience and unwillingness to volunteer information to a patient asking many important questions. i will never chose a doctor who withholds info or makes me feel i am a burden by seeking info.
i have another appointment at the end of the month and after discovering this site all the great info, opinions and caveats, i realize i need to do even more research before proceeding so thanks to all who share info and experiences
Lynda111 Dapperdan7
Posted
Yes, do research. And not just on cataracts. Do research on all medical issues, if at all possible . This forum was very helpful. Cornea/Anterior Segment ophthalmologists are specialists in cataract surgery. See more than one, even if you have to travel.
With all that said, most cataract surgeries do turn out well for most patients. New technology will only make cataract surgery better in the future.
thomas84367 Dapperdan7
Edited
Upon being diagnosed with cataracts, but prior to meeting with my surgeon for the first time, I thought "Oh, okay. They're going to replace my natural cloudy lens with an artificial lens, I'll have 20/20 vision for the first time since I was a teenager, and it's covered by my insurance. Wheee!"
Then I met with my surgeon for the first time and he explained to me that due to my astigmatism, I would likely need to wear corrective lenses for most daily activities after the surgery. (This was after I informed him that I wasn't considering laser assisted surgery to correct my astigmatism or premium lenses.)
Wait. Hold up. I'm getting cataract surgery, and my eyesight is going to be WORSE than it was before the cataracts developed? I still had excellent intermediate and near vision prior to the cataracts, and while my distance vision was definitely below average, it was good enough that I could get by without wearing corrective lenses. I was very upset.
That's when I began taking this seriously and became obsessed with learning as much about cataracts, cataract surgeries, and lens options as possible. Forget what insurance covers. I'm going to have to live with this decision every waking moment for the rest of my life, and I'm only 56. Now every option was on the table.
I scheduled a second consultation with my eye surgeon. This time I was I was fairly well informed, and he and his assistant were the polar opposites of impatient and unwilling to volunteer information. They loved me. That's when I began to appreciate what it must be like to be on their side of the fence and have to try to explain something this complex to clueless patients (like I was on my first visit) every day, day in and day out.
My point being that if your surgeon doesn't appreciate you taking a vested interest in your cataract surgery and asking thoughtful and intelligent questions, you've got the wrong surgeon. If they're truly passionate about what they do, you should be one of the highlights of their day, and maybe even their entire week...and vice versa. I'm actually going to be a little sad when this is all over and I don't have any more appointments with my surgeon. He's been awesome to work with.
Dapperdan7 thomas84367
Posted
excellent post sir! much appreciated. i plan on knowing EVERY aspect i can as it is important
Spring1951 Dapperdan7
Posted
I think that they don't have time to give much info. and seem to want to run you through tests, say a few sentences and get you out the door. I have had two bad experiences with optometrists and also one years ago who neglected to tell me I had macular degeneration (it was in the summary notes which I didn't usually read). My new eye doctor will answer questions but I always feel that there is this acute time pressure and I don't want to waste her time which is why I gather the info on my own (which can be hard)......even if these doctors would have good write ups with lots of detail that would help and most would be happy to read it to get the information. I am with Kaiser Permanente so they are known, btw, to be focused on cost cutting as an HMO
so I do a lot of work and research on my own!
Spring1951 thomas84367
Posted
In reading your post you sound similar to me in that I have been in a state of disbelief over actually having my eyesight get worse since my near, intermediate and distance vision is good. I don't even wear glasses. How did you resolve this issue and what is going to be your focal point. My doctor seemed to think i should pick intermediate which is 20 to 40 inches. I hardly use that zone in my daily activities. How are you going to cope with losing the good eyesight you have now or have they clued you in that it won't be as extreme as you thought? Are your eyes going to get truly worse or did your research show that they will not? How much benefit are your going to get as opposed to the down side?
RonAKA Dapperdan7
Edited
There is nothing wrong with getting both eyes set for close distance. For sure you will have to get prescription glasses to see well in the distance and drive. And if you don't want to keep taking your glasses on and off you will need bifocals or progressives. The other minor issue is that your glasses will be a bit thicker than if your eyes are corrected for distance.
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If you have the lenses set for distance you may be able to get away with OTC readers instead of prescription glasses. But, cataract surgery is not as precise as eyeglasses and to get the best vision it may be worthwhile to get prescription, to correct any unexpected residual error in sphere and cylinder.
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My solution to this is to get one eye for distance and the other to see close (target -1.5 D). I like it a lot and almost never wear glasses. For very small print in dimmer light I will occasionally use some +1.25 readers. And for the best vision at night out in the country I have some prescription progressives that I will use.
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On my eye set for distance (0.00 sphere, -0.50 cylinder) I can see a computer monitor down to about 18", although that seems better than average. 2-2.5 feet may be more typical. One my close eye I have astigmatism issues and is not the ideal -1.5 D sphere. I am at -1.0 D sphere and -0.75 D cylinder. The spherical equivalent of this is about -1.40 D. I can't see as close as when I was quite myopic in the -3.0 D range, but I can see to 10" or so in good light. For real close I use some stronger readers or my progressives.
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You say you are doing your research for the future. The one bit of advice I would give you if mini-monovision is of interest is to do a trial now using contacts. Target plano distance in the dominant eye, and -1.5 D in the non-dominant. The catch 22 that many of us get into is that we let the cataract progress to point where it is difficult to do a contact trial where the results are hard to evaluate due to the cataract impairing vision.
RonAKA Dapperdan7
Posted
I noticed that you have asked about defocus curves and depth of focus. It is a somewhat complicated subject but let me try and explain. For reference have a look at this article:
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Review of Ophthalmology PUBLISHED 15 APRIL 2021 IOL Review: 2021 Newcomers
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And in particular look at Figure 1 and the left hand graph which is titled US Trial. This shows a defocus curve for a monofocal lens (grey line), and a Vivity Extended Depth of Focus (EDOF) lens (blue line). But for now lets just look at the grey monofocal one. The vertical axis is LogMAR which is a measure of visual acuity. The 0 position is 20/20 vision. The 0.2 position is about 20/32 and considered to be the limit of good vision. When the curve is above 0.2 that is good vision, and below that vision is starting to get fuzzy. The horizontal axis is the defocus position which can be converted to distance by dividing 1 meter by the defocus number. So -1.0 is 1 meter or about 3 feet. -2.0 is 1/2 of a meter or about 1.5 foot. So as you move to the right on this graph the distance gets closer and closer. It is worth noting that the vision peaks at defocus 0.0 which if you divide 1 meter by zero you get infinity. That is essentially distance vision. So normal practice is to target the IOL to have peak acuity the 0.0 position or a bit right of that at -0.25 D. As you can see vision does not drop off a cliff as you get closer. It gradually drops off. The grey monofocal line hits the 0.2 LogMAR visual acuity point at about -1.5 D, or two thirds of a meter or about 2 feet. For most people the car instruments are still quite clear with a monofocal set for full distance.
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Now if you look at the blue Vivity EDOF curve you can see that the peak acuity point is compromised some, but the drop off is less steep. It does not hit the 0.2 LogMAR until about -2.0 or a half a meter. So while there is a lot of hype around EDOF lenses you actually gain only about 6" of closer vision by going from a monofocal to a Vivity.
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The other option to get better close vision is to use monovision. In this strategy instead of targeting the peak vision for the lens at 0.0 D, one eye, usually the non dominant one, is targeted to -1.5 D. This means that the whole visual acuity curve for this lens moves 1.5 positions to the right. This eye will have 20/20 vision at 2 feet and will not hit the 0.2 LogMAR until about -3.0 D or 1 foot. So you have one eye with peak vision at distance, and the other with peak vision at 2 feet. When the drop off curve is considered you get good overall vision from infinity down to about 1 foot without eyeglasses. Near vision with this mini-monovision configuration will far exceed having a Vivity lens set for distance in both eyes.
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Keep in mind these curves are the outcomes of trial data where they measure the vision of all the subjects in the trial. While only one line is shown, there can be significant individual variability from person to person. The line is the mean of everyone in the trial.
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I hope that explains it. If you have questions just ask, and I will see what I can fill in.
Dapperdan7 RonAKA
Posted
hey ron. well i have been trying the mini monovision and it has been interesting.
so far, i have used plano,-.5/-1.0/-1.50/-2.0.
ill be doing -.75/-125 in the near future.
it has woken me up to the compromises one must understand about future choices involving surgery.
i first did -2.0. did not like it. not right off the bat. next i did -
Dapperdan7
Posted
next i did -1.5. better but still annoying .plano was wonderful since
both eyes were corrected but the annoyance of needing glasses for so much
would mean lots of on and off with glasses based on my life style. this experiment really shows how the reality would be.
-1.0 or -1.25 seem the best compromise so far. i did a second whole day with -2.0
and i have to say it was nice to be able to read near without glasses. the loss of the intermediate kind of sucked though. but it still was not bad. when they say the brain cant "neuroadapt" at the distance, i have
to wonder if neuroadapt is the right term. if i chose the -2.0 i would always see the vision gap but not that much more annoying than -1. maybe there is an annoyance defocus curve too. maybe acceptance is better than neroadapt as a term. or maybe one is the other.
anyway
thx for the defocus curve explanation. im really beginning to understand concepts that are CRITICAL to making the best choices.
dan
RonAKA Dapperdan7
Posted
"-1.0 or -1.25 seem the best compromise so far."
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Keep in mind that you likely still have some accommodation ability in your natural lens. This will make these lesser options for myopia seem better than they will be with an IOL lens. I found that I needed -1.50 D in an IOL to get the equivalent of -1.25 D with a my natural lens and a contact.
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I am surprised that you would need -2.0 D to read. -1.5 D should be lots to read normal text, a computer screen, and a smartphone.
Bookwoman RonAKA
Posted
I can read books (real, printed ones) much better with my -2.5/-2.0 combo than I could if both eyes were -2.0. And if I had -1.5 vision in both eyes my arms wouldn't be long enough!
RonAKA Bookwoman
Edited
It may be an issue of having super easy reading vs having just good enough reading. My -1.0 D sphere and -0.75 D cylinder (-1.4 D SE) is in the just good enough category. I think I could see much better if I was a pure -1.5 D sphere and no cylinder. My issue with wearing readers that give me in the range of -2.5 D is that I cannot stand wearing them when looking into the distance. They have to come off immediately when I am done looking at something close.
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I think with monovision one needs to go with just good enough reading vs very easy reading. I think the other issue is that each individual is a bit different in what they need.
Bookwoman RonAKA
Posted
Yes, that makes sense. I wanted my book-reading vision to be exceedingly crisp since I do so much of it. That's not the case for everyone.