Monovision - First eye for near vision

I think you have taken a couple of steps up and one back with the new ophthalmologist. Monovision is good, and the Clareon lens is good too. I have one. However, I would caution you on going for -2.5 D or even -2.0 D in the near eye. That is too much if you plan to target plano (-0.25 D target) with the distance eye. I am curious. How much myopia and differential between the eyes have you had with the Lasik correction?

I'm curious about that too!

I am currently +.025 in my good eye and -6.00 in the bad eye, but that is much worsened by the recent cataract. I am trying to find some record from before the cataract, but no luck yet. I do have an old pair of glasses - perhaps I can get the lenses analyzed by an optometrist; that prescription would probably be a good estimate of my refractive state during the 25 years before the cataract.

Yes, if you have been seeing an optometrist on a regular basis they should have records of your refraction over the years. You would want to go back prior to cataracts as they can change refraction significantly. And a cooperative optometrist or optical dispensary should be able to accurately read the prescription from some old glasses too.

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Simulating monovision with contacts is another option if you are seeing well enough with a contact correction to properly evaluate the vision.

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In a post below which will be delayed for moderation, I will include a couple of graphs from a study which was done to determine the ideal amount of myopia in the near eye for monovision. Will not show up until tomorrow...

The problem with going to higher levels of myopia like -2.5 in the near eye, which is full monovision, is that you can get a disorienting effect from the differential between the eyes, anisometropia. For that reason one should not go significantly above a 1.5 D differential. The other issue is that the more myopia you go for with the near eye, the lower the visual acuity at intermediate distances, with a loss in depth perception or binocular vision. See this figure which graphs visual acuity vs distance with varying amounts of anisometropia. As you can see the -2.0 D curve shows a significant dip at 0.7 meters or about 2 feet. A 2.5 D is not shown but it would be even worse.

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The following bar graph shows the loss in binocular vision for the various amounts of anisometropia. There is some loss at 1.5 D but significantly more at 2.0 D. Again 2.5 D would be worse still. The conclusion of this study was that 1.5 D was the optimum amount of anisometropia for monovision.

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Thanks, I will keep looking into it. Problem is, I practically never saw an optometrist, because my eyes were fine for 25+ years. I only got glasses about once every 10 years, just cuz I had a vision benefit. Never wore them. Those were the good old days!

I would try the contact lens, but I'm afraid it would be hard for me to evaluate the monovision at this point, now that I am accustomed to -6.00 D. My current vision actually doesn't bother me much - I can still read fine print with either eye, even though I'm in my mid 60s, and I still never wear glasses. Unfortunately, it will continue to worsen...

The monovision setting question makes me want to consider the RxLAL adjustable lense that trilemma suggested above - the ability to fine-tune vision and monovision after insertion sounds awesome, though no doubt there may be some drawbacks, too.

Thank you, RonAKA, this is very helpful getting me started, and I will plan to do some more research.

One question: in the first chart you posted, why are they studying CDVA? Isn't uncorrected vision the relevant measurement? Perhaps I'm not understanding the terms used in the study.

If your corrected vision is still good in the -6.0 D eye, the contact lens simulation would be of value. You would want to correct it down to -1.5 D for the simulation. You could correct the other eye to plano, but +0.25 is a very small error and you likely would not notice it. You could also try the -2.5 and -2.0 D options recommended by the surgeon. If you can tolerate the -6.0 D then you may be able to tolerate the full monovision. It has fallen out of favour because most cannot tolerate that much anisometropia.

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This disadvantages of LAL is the cost which is significant due to the numerous office visits required to adjust the lens, and also the need to wear UV protective glasses to keep the lens safe from natural UV until the final setting is achieved and the correction made permanent. If the service is not available locally there would also be the travel costs.

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Unfortunately the details of that study has been taken down, and only the graphs with a bit of an explanation under each one is left. All I can think of is that they are considering the IOL correction as corrected vision. There is no doubt that the curves they present are uncorrected (in the normal sense) vision defocus curves for each target for the lenses. If you google this you should find what remains of the publication with the rest of the figures and tables.

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Semantic Scholar Optimal amount of anisometropia for pseudophakic monovision. Ken Hayashi, Motoaki Yoshida, +1 author H. Hayashi Published 1 May 2011 Medicine Journal of refractive surgery

Thanks, RonAKA, I really appreciate your help!

Vision is important, so I'm not going to worry about cost or extra visits if the RxLAL lens turns out to be best for me. I see it is pretty pricey, what with the cost of the lens and the extra work by the optometrist. But if it works well in the long run, worth every penny.

Others here who have done or investigated LAL will be able to give you a better idea, but I think you are looking at something north of $10,000 US for LAL. It probably has the least risk in hitting the targets for each eye more exactly.

Well, I did get my pre-cataract prescription -- optician read it from an old pair of glasses.

My near-vision eye was -1.5 D (and -.25 cylinder) after LASIK correction. It is now at least -6.0 D due to a cataract, while my distance eye is still close to plano and 20/20. Apparently I had what is now called mini monovision for 25+ years, and it worked fine for me.

I expect that similar -1.5 D monovision will be less effective after cataract surgery, since I will be unable to change focus of my artificial lens. But I imagine that targeting my new lens to somewhere in the range of -1.5 D to -2.0 D will give me the best balance of good near vision and some intermediate vision.

It does seem my tolerance for monovision is practically infinite - I had 25+years at -1.5 D, and even now at -6.0 D, the difference between eyes doesn't bother me in the slightest. So whatever gives me the best near/intermediate acuity should be fine.

"As you can see the -2.0 D curve shows a significant dip at 0.7 meters or about 2 feet."

That is a very informative chart! I had to read it several times before I understood the data, but I think I get it now.

As you say, the -2.0 D curve dips at about 0.7m - presumably that's where visual acuity falls into a crack between the near eye and the far eye. However, even that significant dip still gives acuity of about 20/24 at the 0.7m intermediate distance, which sounds pretty darned good. I think I would be fine with that, and I would greatly appreciate the superior near-distance acuity of the -2.0 D monovision curve at 0.3m -- it's approx. 20/30, compared with only 20/38 for the -1.5 D curve.

Of course, my mileage may vary. But if I were able to obtain results like this, I would be very happy with -2.0 D monovision. Maybe even a bit more than 2.0 D?

Thanks again, RonAKA. You da man!

My near-vision eye was -1.5 D (and -.25 cylinder) after LASIK correction. It is now at least -6.0 D due to a cataract, while my distance eye is still close to plano and 20/20. Apparently I had what is now called mini monovision for 25+ years, and it worked fine for me.

I agree with the choices you have reached, but I don't think cataracts would cause that much of a change in focus. Normally it just clouds up the vision. Where did the -6.0 D number come from? A refraction by an optometrist, or an estimate based on needing to hold things 6 or 7 inches from that eye to see things best?

The prescription was determined by my ophthalmologist. She measured the -6.0 D eleven months ago, so I imagine it's even worse now. Apparently a cataract can do that.

I do not notice any cloudiness in my vision - at least not yet. I still see quite clearly at close range in the cataract eye.

She measured the -6.0 D eleven months ago, so I imagine it's even worse now. Apparently a cataract can do that.

I was unaware of that, but searching turns up references. I did not see a magnitude.

What was your prescription years ago?

Yes, it appears you had standard mini-monovision. This should give you a lot of confidence that it will work well for you with IOLs. Yes going for more myopia than -1.50 D will give you better reading. I experimented some when I had one eye done and the other not and concluded that I could get away with -1.25 D to read with my natural eye (at age 70), as it appeared to still have some accommodation. But, to get the same vision with an IOL I needed -1.50 D. I think -1.75 D may be the limit. If you do the distance eye first and hit the standard distance target of -0.25 D, then you can go to -1.75 D without exceeding the differential of 1.5 D.

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If you look at those other graphs you will find distance and depth perception suffers if you go too high with the differential between the eyes.

Standard monovison I believe is about -2.5 in the near eye. My surgeon said he has done as much as -3.0 D! Standard monovision gives very good reading vision, but it is not done much any longer because many see the dropout in vision at the intermediate distance and don't adjust well to the differential. That seems to not be an issue for you.

"...distance and depth perception suffers if you go too high with the differential between the eyes."

Yes, no doubt it does suffer somewhat. However, I seem to do fine with depth perception now, at over 6.0 D difference. The only problem I have noticed is when tossing a tennis ball as I'm serving. My depth perception is quite sufficient for other parts of the game, and for all aspects of daily life, as far as I can tell.

I have to accept that my vision is no longer close to perfect, and that it probably won't ever get much better than it is right now. Not being an athlete or a pilot, I need sharp visual acuity a lot more than I need precise depth perception. So if I can get adequate reading, intermediate, and distant vision -- even if depth perception suffers -- I will take it!

Before the cataract, I was -1.50 D. After cataract, the same eye measured -6.0 D. So, the cataract has so far added about 4.5 D worth of myopia.

Seems I have a long way to go if I want to break the record - a quick googling turns up a woman who gained 16.0 D of myopia over a 10 year period from "cataract-induced refractive change" or CIRC.

When I was doing my trials in preparation for mini-monovision with contacts I was initially convinced that -1.25 D was enough. However, I got my distance eye done first which ended up at -0.25 D, essentially perfect. I then used +1.25, +1.50, and +1.75 D readers to simulate reading ability with my new IOL eye at the varying amounts of myopia. That is how I determined I needed to go to -1.50 D instead of -1.25 D. But, in your case you are doing the near eye first, so you kind of have to go for broke on the target for this eye. But, from what you say, it would seem pretty certain you can tolerate more than the average person for anisometropia.

"in your case you are doing the near eye first, so you kind of have to go for broke on the target for this eye."

That makes sense. I'm also thinking that the Light Adjustable Lens could offer me the same kind of flexibility you had to try out options for your near eye. My good eye is still close to 20/20, so I should get a good sense of the monovision so long as I get the operation before my good eye materially worsens.

I will need to be careful about the intermediate vision, however. I do a lot of computer work (and leisure) at around 30 inches' distance. I can still see that distance very well with my good (distance) eye, but when I eventually have my second cataract removed, I suspect I will need to rely mainly on my near-vision eye for intermediate distance vision. Or maybe it will be more a combination of the two eyes. Perhaps I will consider a second Light Adjustable Lens at that time, to increase my chances of a satisfactory outcome across all distances. Hoepfully, I won't have to make that decision for a number of years.

.As you have seen on that graph the peak vision for a -1.50 D target peaks at about 0.7 meters or 28". It probably would give you near ideal vision for using a computer monitor at 30" as long it is of the larger screen variety. A -2.0 peaks significantly closer at about 20". So that would leave the 20" to possibly as much as 3' a bit iffy. My distance eye gets me down to 18" with ok vision, and 24" with good vision. But these results vary quite a bit from person to person. A monofocal set for distance can start to jam out at as much as 3 feet if you are unlucky. It seems those who are quite myopic before cataracts and surgery tend to see closer, and as well for those with smaller pupils, which probably really means older people as the pupil size decreases with age.

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Yes, -1.5 D looks great for intermediate distance, while 2.0 D is better for closer distances, reading a phone display and such.

It sounds like you get a very good range from your distance eye - quite similar to what I have right now in my good, natural eye. I can only hope my result is as good as yours, when I need an artificial lens in my distance eye sometime in the future. Meanwhile, I hope to get good near vision, and ok intermediate vision from my first artificial lens next year.

"... ideal vision for using a computer monitor at 30" as long it is of the larger screen variety."

BTW, I use a 32" monitor at 2.5k resolution. Measuring a little more carefully, I view it from about 30" to 36" distance. Of course, I can't read it with my cataract eye, so I see it with my ~20/20 eye. Works great for me, and cost only a couple hundred bucks. Highly recommended - more convenient than reading glasses.

It is different when I travel and have to use my laptop - it has a 16" screen, and I need to press my nose to the screen (well, almost) to read it with my bad eye. My co-workers feel sorry for me; one even offered me his glasses during my last business trip! I suppose I should just get myself a new pair of glasses, but it's been 40 years since I wore glasses, and I don't want to wear them now...

My monitor is 20-24" away and is a 24" monitor. I keep all the text the standard size and it works well for me. I can actually read it with my eye that is set for distance (-.375), but it is much more comfortable reading it with my close eye (-1.6 D). Of course I have both eyes open to use the computer but I suspect my brain is mainly using the close eye.

A pair of 2.0D readers should be good when using the laptop. Readers can be very cheap.