Pupil size and lens choice
Posted , 8 users are following.
I had an interesting discussion with one of my ophthalmologists the other day. He is recommending the Symfony OptiBlue lens for me, in large part because my pupils are "small", and his experience - including an older Symfony lens in his own eye - is that this lens will work well with my pupil size.
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I told him I was interested in trifocal lenses, because I use my cataract eye for near/reading vision now and I want to retain the best near vision that is reasonably obtainable. He advised against it, on the grounds that trifocal lenses do not work well for us small-pupil patients. Instead, he said he could target -.25 D on the OptiBlue, to provide better reading vision. He said he could maybe try as much as -.50 D, but definitely no more than that because targeting greater myopia causes visual effects like glare or halos with the Symfony lens.
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I don't see many of these findings/opinions about pupil size and IOL selection on the interweb. I am particularly curious about the idea that trifocal lenses are incompatible with small pupils - why would that be? I wish I had thought to ask the doctor, but I did not.
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What do you all think? Is pupil size important in choosing a lens?
0 likes, 39 replies
billy111 phil09
Edited
Do a search for "eyes on eye care resources the webinar that finally got you talking"
Once you get there, scroll down until it says "Where do I begin"
It's not a video but a discussion among several cataract surgeons comparing the Symfony Optiblue with the Panoptix. Goes into discussion of importance of defocus curve. It does say this about small pupils:'
“I think that's what tripped everyone up in the beginning,” she explained. “I think we've talked about this before, but it is pupil size that probably determines the depth of focus. The smaller the pupil size with the Vivity lens, the more depth of focus you could get"
This is dated August 2023
RonAKA phil09
Edited
Here is the name of one of the few articles I recall that considers pupil size when making choices for monovision. I think they are basically taking advantage of a smaller pupil pinhole effect that has a larger depth of focus naturally to use less myopia in the near eye. A quote:
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"We currently use monovision with pseudo accommodation in
patients with pupil diameters of less than 2.5 mm [4]. In our practice,
the target refraction is emmetropia (0 to −0.5 D) in the dominant
eye and slight myopia (−1.0 to −1.5 D) in the non dominant eye if
the pupil diameter is 2.5 mm or less."
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Clinics in Surgery
2018 | Volume 3 | Article 2027
Monovision Strategies: Our Experience and Approach on
Pseudophakic Monovision
Misae Ito CO, Shimizu K.
phil09 RonAKA
Posted
Thanks, RonAKA. Now I'll need to get a numerical measurement for my small pupils, and find out which eye is dominant. None of the three ophthalmologists I've consulted has mentioned anything about dominance.
But even just knowing my pupils are "small", perhaps I can expect some of that "pseudo accommodation" and take some comfort in that. Though I imagine there must also be some downsides to small pupils - there is no free lunch.
RonAKA phil09
Edited
Determining your dominant eye is fairly easy. Just extend your arm and point at a distant object with your finger. Close your right eye and see if you are still pointing at the object. If you are, then you are right eye dominant. If not, then left eye dominant.
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The downside of small pupils is going to be night vision, and reading in dim light. It is kind of a given with older age.
phil09 RonAKA
Posted
I think I flunked this test. 😉 If I focus on the distant object, I see two fingers at arm's length, and vice versa.
The finger I see with my left eye is more solid. But if I bring the finger close to my eyes, this reverses and my right eye sees the more solid finger. I am very nearsighted in my right eye, so I'm thinking that this test doesn't tell me very much - at arm's length and beyond, my left eye is dominant, but at close range, my right eye dominates. Because my two eyes see at very different depths, perhaps the concept of dominance is not even meaningful in my situation.
RonAKA phil09
Edited
You would need to do this test with your glasses on or corrective lenses in. Another way of doing it is to make a circle with your thumb and first finger and hold it out as far as you can and circle a small object in the distance, and then close one eye.
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At the end of the day I am not sure eye dominance is a critical factor in mini-monovision. There is no solid consensus that the distance eye should be the dominant eye. Some say it should be the reverse. My surgeon says it does not matter. Kind of out of happenstance I ended up with my near eye as the dominant eye. It is called crossed monovision. It works as my surgeon predicted.
phil09 RonAKA
Posted
That would make sense. Because my myopia is steadily increasing due to the cataract in my right eye, I have no useful corrective lenses, and probably won't till after my surgery.
Lynda111 phil09
Edited
I think it would simpler, easier, less risky and a lot less expensive if you went with monofocals as Ron advised.
phil09 Lynda111
Posted
Thanks, Lynda111. I agree there is much to be said for that approach. I am strongly considering it.
steven64823 phil09
Edited
There's some good information available if you search for "effect of pupil size for EDOF IOLs". The result should also show additional discussions on this topic.
I attempted to convey this previously but it was deleted.
phil09 steven64823
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Thank you, steven648, i will take a look.
RonAKA phil09
Edited
Another contributor here gave me a link to a Mayo Clinic video on their experience with the LAL. I have not made my way all the way through it yet. A hockey game interrupted me! But, in the early part of it they said one of the exclusions for the lens was someone that had small pupils. By that they mean pupils that will not dilate large enough with the dilation drops. They need a minimum dilation of 6.5 mm, I recall, to get enough access to the lens to do the UV treatment steps. They need to get right out to the edges of the lens when it is in the eye. If you were considering the LAL that is something you should check into.
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One other point that may be of interest is that the surgeon said 30% of their patients who use the lens have had prior refractive surgery, which is high. He said that the LAL has pros and cons for previous refractive surgery patients. The pro of course is lower risk of a refractive surprise once adjustments are done. The con is that these patients as you know can have higher order aberrations, and the lens is not able to correct these with adjustments and these patients they may not be satisfied with the outcome.
phil09 RonAKA
Posted
"The con is that these patients as you know can have higher order aberrations, and the lens is not able to correct these with adjustments and these patients they may not be satisfied with the outcome."
Sure, but isn't this true of every IOL? My understanding is that no lens can correct higher order abberations.
My surgeon mentioned that "topography LASIK" is the only known method to correct those abberations. He also suggested that the software for this type of LASIK is currently somewhat primitive, but may well improve over time. I doubt I will ever need such treatment, as my vision has been quite good, and hopefully that continues after cataract treatment. Regardless, nice to know that better treatments are becoming available.
RonAKA phil09
Posted
It is true that no lens can correct these higher order aberrations. However, there are lenses which are more tolerant to the aberrations than others. The least tolerant would be multifocal lenses, and next would lenses like the Tecnis 1 which attempt to fully correct all spherical aberrations (lower order) to zero. The reason is that these lenses have varying correction power dependent on the distance from the center of the lens. The enVista is one that would be more tolerant because it has zero spherical aberration correction, and has a uniform power from the middle of the lens to the outside. The Eyhance may also be a poor choice because it varies the power from the middle to the outside, especially near the middle of the lens.
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I put a lot of time into investigating the topography guided Lasik, sometimes called Custom Lasik process or wavefront guided, and what the best equipment is to do it. I had high hopes that it would correct my irregular astigmatism (keratoconus). I saw two clinics before I gave up on it. The problems is that when you correct the astigmatism the overall spherical equivalent goes closer to plano and myopia is reduced. I wanted more myopia at the same time and they claim they cannot predictably do that. The second clinic I saw had the best equipment, but still would not touch it, because they were afraid that the cornea was too thin, and would not behave well. I gave up on it. So, be careful especially if you have keratoconus.
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If you want to google it, the clinic I found that had the best equipment in our city is the Eye Q Premium Laser. Check under Our Services, Lasik, Custom Lasik for a description of what they have. Their laser is the SCHWIND AMARIS® 750S and they claim it is the best. Actually there is a later and probably better version called the SCHWIND AMARIS 1050RS if you can find a clinic that has it. Given your previous laser surgery it seems hard to justify doing more Lasik though. I still would lean towards using a lens tolerant to what you have now.
RonAKA phil09
Posted
With thanks to @julie66167 for finding it, here is the link to the Mayo Clinic Video presentation on the LAL. It goes a long way in explaining the intricacies and limitations in using the LAL.
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https://medprofvideos.mayoclinic.org/videos/light-adjustable-lens-what-every-ophthalmologist-should-know-webinar