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Upgrade the memory of your 2018 Mac mini up to 64GB

Multifocal or Presbyopia-Correcting Human Eye Lens Implants (IOL)

W James G writes:

I am an ophthalmologist. My medical group does a lot of cataract surgery and in the past few years we have had the benefit of a number of new technologies for the lens implants we use. We can now correct corneal astigmatism with the lens implant (IOL) doing the correcting inside the eye. Since the correction is much closer to the nodal point of the eye the quality of the vision is much better than if the astigmatism is corrected with spectacles. This technology is especially awesome for patients with higher levels of astigmatism.

We also have a wide array of multifocal or presbyopia-correcting lens implants, some of which now also can do the astigmatism correction. The multifocal IOLs use a number of technologies and these technologies are continually improving, with the road to better vision paved with the discards of obsolete-technology IOLs. The two main competing technologies now are 1) an apodized circular diffraction grating on the IOL which creates two different focal distances in the same lens and 2) a similar concentric ring IOL with extended depth of focus (EDOF).

The advantage to the latter is that patients have an IOL that is continually sharp from infinity to about 20-22 inches. There is some tradeoff in ultimate acuity but these differences appear to be significant only in the optical lab but not in clinical usage. I have been very impressed with the patients I have put EDOF lenses in. It is pretty remarkable in terms of what they can see and the quality of their uncorrected vision.

What I DO NOT KNOW is how patients with multifocal IOLs handle a camera viewfinder, both in terms of the subject image they see and also the ability to see the peripheral stuff in some viewfinders like f stop, shutter speed, ISO, etc.

Have you had any feedback from patients on this? If not, could I ask you to send out a query as to what your readers’ experiences have been? The results would go a long way toward helping us make recommendations to our serious photographers.

DIGLLOYD: I suppose the first task of any ophthalmologist is to learn to spell it!

Since I wish I could have contacts accurate to 1/4 diopter, I am not sure about the “lab vs clinical” thing—I find I am very picky and notice even small differences. Even 9.5 vs 10 diopters in contact lenses is a big difference that precludes comfortable computer use at 10 diopters.

My own father had the lens replaced in two eyes, but neither was continuous focus, and one was not entirely satisfactory. By the time I need a lens replacement, I hope this technology is tried and true and (can I hope) as good as the original lens in my 30's.

Readers: email comments and indicate if it is OK to pass along your name and email. That aside, all comments will be posted for public view in this post.

Paul B writes:

I have these IOLs (had since 2015) and no issues at all with camera viewfinders. I can see all of the info at the edges of the screen as well as the main subject. Works great with my both my D800 and Z7. You can pass my name/number onto the ophthalmologist!

DIGLLOYD: good news it seems.

Rich S writes:

There was a great article on cataracts correction a few years back in Sky and Telescope with a focus on maintain optimum quality for telescope viewing which is a extremely high contrast environment. I don’t have it handy, but what I recall is that the diffraction gratings described cause significant artifacting because of the grating. A normal user in typical conditions would not be bothered by it, but the author, an experienced astronomer found them to be a no go.

I have some early cataracts induced by chemotherapy, so this is of great interest to me. MY conclusion is that all these “fancy” lenses for the average person would not work for me, someone who is used to looking at the most minute detail and color for the last 20+ years, and I would need a very traditional lens that would still require glasses for either distance or near correction.

This article was a must read in my opinion for anyone facing cataract lens replacement surgery. I find few optometrists or ophthalmologists are sensitive to the needs of people like you and me trained to view with such precision, and as such, apply “common” solutions to our “uncommon” need.

https://www.skyandtelescope.com/sky-and-telescope-magazine/inside-september-2014-issue-2/

DIGLLOYD: this is indeed my concern also were I to need a lens replacement.


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