Mini-monovision with near / intermediate bias

[TillyMack]

In terms of mini-monovision, I've read that plano is generally the target for the distance eye.  I've also read that that the brain can only pick the best distance image if it is close to plano. That said, I'd like to know how the brain works with mini-monovision with near / intermediate bias which is one of the options I'm considering.
Many thanks!

[JohnHaganMD]

Answered on one of your other postings

[Ron_AKA]

The Mayo Clinic has a very interesting Webinar video on their experience with the LAL - "Light Adjustable Lens - What every ophthalmologist should know"

https://medprofvideos.mayoclinic.org/videos/light-adjustable-lens-what-every-ophthalmologist-should-know-webinar

A couple of interesting points in the video:
7:40 - They present statistics that show 80% of mini-monovision (blended vision) patients get 20/20 vision for both near and far, compared to only 40% using PanOptix multifocal lenses.
23:14 - A graph is shown for the patient selected steps in refining the near vision target refraction. the large majority select -1.3 to -1.5 D.

To me this Mayo Clinic experience confirms that that target for mini-monovision of -0.25 D distance and -1.50 D are optimum. This is what patients select that have 3-4 do-overs to finalize their choices.

[John C Hagan III, MD, FACS, FAAO]

RonAKA: thanks for the LAL information. In our Kansas City practice it has become the most popular premium IOL and much better received than any of the previous generation of premium IOLs.    The patient is paying a premium for the ability to adjust to their individual preferences so the need for post op adjustments is to be expected and is included.

[Ron_AKA]

I have never seen any credible information that there is a requirement to have one eye close to plano. The brain is quit adept to selecting the best image from what is available to it. Studies have been done on using the dominant eye vs the non dominant eye for distance vision. While the convention is to do the dominant eye for distance, some have suggested the reverse, crossed monovision, is better. My conclusion is the brain sorts it out.

[JohnHaganMD]

If an eye has no residual refractive error that is 0.00 diopters then vision will be clear (assuming the rest of the eye is normal) 10 ft (6 m) or further.  Anything closer will be blurred and the closer it gets the more blurry. Thus a TV at 12 ft, a computer screen at 2 feet ad phone or book at 18 inches will not be clear.

[TillyMack]

Thanks so much for addressing my concern!  To confirm, things closer than 10 feet or further from a person with plano vision will be blurred.  The closer the object gets, the more blurry the object looks to that person.  Got it!  My related question concerns clarity of vision indoors.  I'm wondering if it is worth pursuing mini-monovision with near bias to improve my visual acuity inside the house.  I should say that I have no experience with mini-monovision and would like to stay within a conservative offset similar to what is found among the general population.  For example, pairing my operated eye (-2.0) with an IOL targeting more distance (anywhere from -1.75 to -1.25).  In other words, I'm assuming a small offset of some degree would be better than both lenses being set to the same -2.0 target but I'm not sure if it matters in this context.  Many thanks Dr. Hagan for your kind assistance.  

[John C Hagan III, MD, FACS, FAAO]

To get meaningful mini-mono near bias most surgeons would recommend about 0-1.00    Most people will tolerate 2 or less diopters between the two eyes. But you should discuss with your surgeon. For near-sighted people like me who all my life can read without glasses and can do the computer without glasses I would be very unappy post CAT/IOL (which I have not had) to have to wear glasses for those things.  I have had myopes tell me the greatest thing in the world would be to see far away without glasses and request  0.00 (plano) in both eyes. I would never do surgery on those people. Eventually they found a surgeon that would and some came back to me extremely distraught that they needed glasses for near and intermediate.  Also the range of focus of and resideual IOL power will depend somewhat on the size of the pupil, smaller pupils given larger depth of focus and of couse the type of IOL.

[TillyMack]

Dr. Hagan, Thank you so much for addressing my concerns!  It is helpful to know that if I decide to choose mini-monovision with near-intermediate bias, I should choose at least -1.0 D.  Otherwise I would choose both eyes the same for the benefits of that configuration.

[John C Hagan III, MD, FACS, FAAO]

=

[Ron_AKA]

The visual acuity benefits of having both eyes at -2.0 D over one eye at 2.0 D is so small it it almost trivial. Yes there will be a bit of binocular summation but it will be hardly enough to notice. The larger gain would be 3D vision at those very close distances if you have any activities you do at that close (18" or so). However, it will be of essentially zero help in seeing the TV at 10 or 20 feet any clearer.
.
If your interest is getting some better vision of the TV across the room, you need significantly less myopia in the second eye. When you get your current refraction for the first eye, I would take that refraction and reduce it by 1 to 1.25 D and make that your target for the second eye. If you really are in the -2.0 D range with the operated eye it is not going to be enough to give you good 20/20 distance vision, but it will be better than what you have now.

[John C Hagan III, MD, FACS, FAAO]

I do want to point out that for your 'best possible vision' you would need progressive no line glasses with RX  -1.00      and -2.00 and a +3.00 add    just like you can pick up a lot more weight with both hands you can see a lot better with both eyes and of course depth persecption is much better.    also many physicians, myself included, do not target Plano (0.00) for distance. The error for most IOL formula have a plus/minus accuracy of about .50 diopter.  Do if the person gets plano, they are happy, if they get 0.50 they are almost always happy, but if they get +0.50 they are unhappy because that is hyperopic (farsighted) and there is no distance that things are entirely clear. It has worked well over the years. Some formula claim plus/minus 0.25 diopter accuracy but the many postings here about not achieving pre-operative goal belies that

[Ron_AKA]

I think the OP is primarily worried about excessive anisometropia from her operated eye which she anticipates will be around -2.0 D. A -0.75 to -1.0 D target should be way more than enough safety margin from crossing over to hyperopia. Agree with the philosophy of targeting mild myopia instead of pure plano. As my surgeon told me, "Nobody ever thanks me for leaving them far sighted!"

[John C Hagan III, MD, FACS, FAAO]

Here I digress, Go Chiefs, Beat the Raiders

[TillyMack]

Thank you Dr. Hagan, After further consideration I have changed my preference to pairing my already implanted -2.0D lens with either another -2.0 lens OR a -1.5D lens.  Could you let me know which would provide the best vision?  For example, I think the -2.0 would provide the best depth perception and the -3.5 the best range.  Please correct me if that is not correct.  Would there be other differences to consider?  Likewise, are there downsides aside from not achieving distance vision? Many thanks!

[John C Hagan III, MD, FACS, FAAO]

You are missing the point. a -3.5 D IOL has very little range, a very very short focal point but a lot of magnification if you have something aboub 4-5 inches from your eye.  Bigger minus numbers LESS the range and MORE the magnification

[TillyMack]

Sorry!  I meant to type -1.5 NOT -3.5 ...

[John C Hagan III, MD, FACS, FAAO]

=