New observations on refracting pseudophakes

[ilanh]

Over the last few years I have experimented with delivering "monovision" to my surgical patients using monofocal lens implants in a similar way that one would use monovision contact lenses. I won't go into detail regarding how I select the best candidates for this or the testing that it involves. The key concept here is that unlike contact lenses, lasik or the natural lens of a presbyopic eye, IOL's provide a pseudoaccomadation of approximately 1 diopter. This means that if I use my IOL master to plan for a post-refractive outcome of -1.75, the majority of my 65+ year old patients will be able to read uncorrected with that eye (as if they were -2.75). This of course would not be the case for seniors who are given +1.75 add reading glasses or contact lenses. Because I can target the reading eye for -1.75 it means that I can target the "distance" eye for -0.50. Even with only a -0.5 in that eye most of them can see not only distance but also intermediate (because of the 1D pseudoaccomodation). Lastly, because the spread between the two eyes is only 1.25 diopter (the difference between -0.50 and -1.75) it is very well tolerated.

This leads to some interesting issues which I am still experimenting with . For example, some of these people will still require spectacle correction to eliminate the monovision at certain times ie: at the baseball game, at the movies, driving at night, doing fine near work. However, when designing near spectacles for them I no longer go the obligatory +2.50 add that one usually uses. For example, my patient above with the monovision implants will NOT need a +2.00 add to supplement his residual -0.50 myopia. His pseudoaccomodation is already helping him significantly. He will probably need about +1.50 or less. The other eye (-1.75) needs no additional add at all.

Likewise, in a patient who I have only done one eye (and targeted -0.5), I will give them an add of +2.00 in the pseudophakic eye, and the full add of +2.50 in their phakic eye.

The concept of pseudoaccomodation is so powerful that I have even begun experimenting with targeting -0.75 postop. I have found that although this leads to somewhat blurry distance vision at night, it completely opens up the intermediate world. Patients can use their cell phones, PDA's, computers, see their food and even read print at hand's length. This may ultimately be the best overall compromise.

I would be quite interested in finding out if others have noted and experimented with this pseudoaccomodation phenomena? If not, you will be pleasantly surprised to see how well it works. I would also be interested in seeing if this works for all lens implants (I use the Acrysof wavefront acrylic implants)

[Barry Santini]

*Very* interesting....

but.....

Just why do "we" all assume that "John Q." so desparately wants or needs to avoid almost any or all eyewear?

And when these same patients avoid eyewear, just how much is the UV protection for their tear film and cornea?

What about depth perception when driving in low-contrast conditions?

Just another viewpoint...

Barry

[drk]

Barry, I think Ilan is obligated to maximize useful vision. That is not to say his goal should be specifically elimination of spectacle correction.

Ilan, there's nothing quite like a refractive surgeon who has a feel for optics. Kinda rare!

I don't get your "pseudoaccommodation" premise. Are you implying some mechanical process (a la Crystalens')? Are you implying some "hyperfocal effect" due to senile miosis? Some beneficial aspheric multifocal effect? Please elaborate.

I do think I can contribute that 3 mm pupils can give a depth of focus of about 1/2D, and that (even in mesopic conditions) a -0.50 overrefraction may not be unacceptable to these folks, especially considering what they've adapted to-- living with their cataracts over the past five or so years.

And experience has shown me that a -0.75D -> -1.25D overrefraction in the non-dominant eye is usually quite tolerable and eminently beneficial (so much so, in fact, that my inevitable refractive surgery overcorrection may be targeted at -0.75 DS OU, the most happy presbyope in the population, which is what I think you're saying about your -0.75 DS "ultimate solution").

In monovision CL fitting, I prefer NOT to introduce a monovision disparity greater than one diopter as a rule...let them wear readers; a good, hedged, strategy.

I think the future, though, may well be in low eccentricity apheric multifocals. Whatever Unilens designed (and B&L manufactures) works suprisingly well. With "feel" that can be developed, a low eccentricity asphere is really fun to work with, and is really harmless to vision. (To non-CL fitters, think of the fun you can have with a Sola Access NVF lens...many combinations.) I think a bilateral "Restore" lens with a very low plus overrefraction outcome with readers is a nice way to go, in theory.

[chip anderson]

IllanaH: Good information. My only question is: Who decides wether the patient should be left myoptic, or monovision or whatever. Is this discussed with the patient? Does he have the option of optimal vision at distance and reading Rx presented prior to surgery? Does he have all the good, bad and ugly of each option explained prior to surgery?


For everyone else Why do you fit monovision contacts. Why not bifocals? There are so many types out there in rigid and soft that almost anything can be done with at least 20/25 (often 20/20++) at distance in each eye and J-1+ at near. Are we just too unskilled or too lazy. Or do we think the patients won't go for expensive fitting?

I know we often hear "I tried bifocals" as we often used to hear "I tried contacts" there are hundreds of things that can be done so just because one attempt, especially someone else's failed, it doesn't mean it can't be done.

Chip

And yes, if I have a patient happy with monovision I don't rock the boat unless it ceases to be satisfactory.

[HarryChiling]

I love the idea of a doctor not pigeon holeing the patient into no distance correction. I often let everyone I know that I would never trade my -4.75 eyes for the life of me, they are to valuable to the amount of deatiled work I do and I enjoy reading and such, I would probably not only like what you are doing for your patients but would recommend it to most myopes. I would imagine it would be very frustrating for a myopic presbyope who has a bunch of up close hobbies or work to lose that.

[ilanh]

Since some people seemed confused about what I wrote I will elaborate. The truly remarkable thing is that there is something here that almost all of us overlooked. I only began to notice this recently after 15 years of surgery. Take an elderly pseudophake who is -1.50 and give him something to read UNCORRECTED. He will read j1to j2. Take an uncorrected elderly phakic patient who is -1.50, he will read J5 to J6. The bottom line is that the reason the pseudophake can read much better is that he is getting another 1 diopter of accomodation from the implant. No other 65 year old can do this: If you put a contact lens on an elderly patient so that they're left with -1.50; they still can't read. If you don't believe it, try it. You will see that pseudophakes defy the usual rules. You will also begin to wonder why you're routinely giving pseudophakes adds of +2.50 when they can read fine with a lot less.

Who do I do this on? Patients who express a strong interest in avoiding glasses altogether. I determine dominance and do some basic sensory testing. I then try to keep the two eyes within 1.25 D of each other eg: -0.50 and -1.75. This will give them an accomodative range of -1.50 to -2.75 due to the IOL effect. They will be able see distance (with the -0.50 eye), to see intermediate (also with the -0.50 eye) and to read (with the -1.75 eye). Almost no one has any problems with 1.25 diopters of anisometropia.

The fascinating thing is that many of these elderly pseudophakes with -0.50 to -0.75 are getting good distance AND great intermediate from the very same eye absolutely uncorrected. Likewise, many -1.75 elderly pseudophakes are getting BOTH intermediate and reading from the same eye. You will never see this in phakic elderly patients.

Incidentally, the reason why contact lens monovision is so poorly tolerated by many people is that in many cases the anisometropia is too much. What is intolerable is not the concept of monovision but the blur factor for distance that you get with the near eye, and the blur for near experience by the distance eye. My IOL monovsion patients do not suffer from this problem because their anisometropia is much less (1.25) and their distance eye (-0.50) is able to accommodate to -1.50 when they read (which puts the distance eye less than one diopter away from perfect reading).

[braheem24]

I've noticed the same phenomenon, have you done any long term studies? I've also noticed it does not last till the next yearly.

BTW, this may be of interest http://www.osnsupersite.com/view.asp?rID=6279

[chip anderson]

This may have a little relevance on the phenomonmen. Many years ago before implants, I had one aphakic patient whose iris's shimmered otherwise he was like all the other aphakic contact lens patients. I asked the surgeon (a very wise, patient, learned man) why his iris's shimmered.
He replied: "Chip usually you have just enough infection and scarring form after surgery to make the iris just stiff enough to hold it's position and allow dillation and contaction of the pupil but not shimmer. Mr. Easterwood appearently healed too well."
Perhaps the new pseudophake has enough looseness in the iris to allow a little flexing that could move the implant a little at near fixation which he may loose over time. Or possibly as you know 50% of pseudophakes develop capsule opacities that have to be opened after a period of time and this may cause them to lose the accomodation like phenon.

Chip

[Robert Martellaro]

I don't get your "pseudoaccommodation" premise. Are you implying some mechanical process (a la Crystalens')? Are you implying some "hyperfocal effect" due to senile miosis? Some beneficial aspheric multifocal effect? Please elaborate.

Probably just pupil size and constriction, possibly from changes in corneal astigmatism, or spherical aberration and other HOAs associated with the IOL. However, I haven't seen any across-the-board increases in near depth of field, or a reduction in add power after monofocal lens implants.

[ilanh]

Probably just pupil size and constriction, possibly from changes in corneal astigmatism, or spherical aberration and other HOAs associated with the IOL. However, I haven't seen any across-the-board increases in near depth of field, or a reduction in add power after monofocal lens implants.

Robert: I assure you that you haven't "seen" it because you haven't looked. Take your next elderly myopic pseudophake who comes in and test their uncorrected near vision. Now compare that with an elderly phakic patient with the same degree of myopia. Let me know your results. I see 30-40 patients daily and most of them are elderly pseudophakes. Despite this, it has only been recently that I discovered this phenomenon and it has really been an "eye opener". Here's how it happened: An elderly patient of mine whose cataracts were removed many years ago and is -1.50 OU. His glasses are -1.50 OU with +2.75 add OU. After several years of seeing him he finally told me; "these glasses are OK but I actually read just as well when I take them off." I assured him that with -1.50 of myopia he could not possibly read up close, only at intermediate. He then proceeded to demonstrate that he could read the J1 line with ease holding the card in his lap. He was the first one of many hundreds that I have tested. A year later I am still experimenting with this and seeing if it across the board or limited to certain implants. I would love any input on this topic.

[Robert Martellaro]

Robert: I assure you that you haven't "seen" it because you haven't looked.

Well, I didn't say I haven't seen it, it just seems to occur infrequently, in both healthy and post-cat. surgery eyes, and then with folks that have very small pupils. Once in a blue moon I'll see someone whose able to bring the card up to 10" and still read J1, with an effective add of +1.00, sometimes even less. I don't understand the mechanism, but it's probably due to a combination of factors, including Chip's suggestion of capsular haze.

An elderly patient of mine whose cataracts were removed many years ago and is -1.50 OU. His glasses are -1.50 OU with +2.75 add OU. After several years of seeing him he finally told me; "these glasses are OK but I actually read just as well when I take them off." I assured him that with -1.50 of myopia he could not possibly read up close, only at intermediate. He then proceeded to demonstrate that he could read the J1 line with ease holding the card in his lap.

The reason he holds it on his lap is because it's uncomfortable to read at 16", at least for any extended period of time, without asthenopic symptoms. It's the old quantity vs quality of vision thing. Alternatively, if he likes to read at 19" (long arms), it's likely that the ADD is overplused, and may explain why he sees no better with the glasses on when reading than when he takes them off. Regardless, if he's not an avid reader, then you have him right where he wants to be- he can putz around the house without glasses, and put them on for driving and TV.

However (here it comes:)), IMO, reduced dependency on corrective lenses (and the compromises in vision/visual comfort that are required to achieve this) can be a good thing for a select few, for most others it borders or slips into a state of denial, for both the patient and the doctor.

He was the first one of many hundreds that I have tested. A year later I am still experimenting with this and seeing if it across the board or limited to certain implants. I would love any input on this topic.

Quoting Feynman- "Science is a way of trying not to fool yourself."

[ilanh]

Robert,
About 1 minute after reading your post I was told that there was a patient "waiting in room 1". She is a 72 yo pseudophake who is -0.25 OU. Her distance vision is 20/30 OU uncorrected. I gave her the reading card and asked her to read without glasses. She read J3 with ease. You will never, ever see a phakic plano 72 year old who can read both distance and near UNCORRECTED. The interesting thing about this patient is that I corrected her bilaterally purely for distance (because she refused the monovision concept). However, here she is with 20/20 uncorrected distance vision but still able to read great. I am seeing this with the vast majority of my patients but am still not sure if it is confined to the IOL that I use in particular or if this is across the board.

[HarryChiling]

It sounds interesting and weather the situation is unique to you or the implants you use, it would make for a good read. You may want to consider writing something up[ on it and a study to track the effects.

[braheem24]

weather the situation is unique to you or the implants you use, it would make for a good read.

Just for you Harry, since you like numbers :)

http://crstoday.com/PDF%20Articles/1106/CRST1106_13.pdf

[peregrinerose]

Is the improved reading from 'pseudoaccommodation' or is it from the improved contrast sensitivity from the implant compared to the natural (and aging) lens? If you take a phakic 72yo vs. a pseudophakic 72 year old, both with -1.50 OU refraction, I agree, the pseudophake will generally read better. However the phakic 72 year old will probably have some degree of lenticular changes, yellowing, etc. If you test both of their contrast sensitivity, the pseudophake will likely have much better contrast sensitivity than the phakic patient.

It is nice to read an ophthalmologist who actually pays attention to the optics and the functional vision of the patient rather than treating everyone like they have identical goals and needs :p

[Robert Martellaro]

Robert,
About 1 minute after reading your post I was told that there was a patient "waiting in room 1". She is a 72 yo pseudophake who is -0.25 OU. Her distance vision is 20/30 OU uncorrected. I gave her the reading card and asked her to read without glasses. She read J3 with ease. You will never, ever see a phakic plano 72 year old who can read both distance and near UNCORRECTED. The interesting thing about this patient is that I corrected her bilaterally purely for distance (because she refused the monovision concept). However, here she is with 20/20 uncorrected distance vision but still able to read great. I am seeing this with the vast majority of my patients but am still not sure if it is confined to the IOL that I use in particular or if this is across the board.

I had a free hour or so this afternoon to research pseudophakic pseudoaccommodation, and came up with imprecise mechanisms, conflicting studies, experimental error and bias, including bias from the patient's own subjective account, and that to be conservative, may be good for about +.50D. However, something is going on here, but the effect may be overstated for some or most pseudophakics.

BTW, you're right, I haven't been looking for it. But I'll have many chances in the months ahead- about ninety percent of my clients are older than age 65. Thanks for the heads up, and for sharing your knowledge and experience.

[Dannyboy]

Do you think the pupil size plays any role ? I do not mean to change the subject of this thread. But when a patient who has had a multifocal IOL implanted and the patient complains that he has to hold the print too close for comfort how do you correct this? I am sure a -.50 to -.75 would help him put the reading at the correct distance but if the patient does not want readers (-.75) to wear all the time because of occupational requirements.Obviously there are not any negative add progressives so would prescribing a med like pilo help ? I have one such patient using it for that problem. Does that make sense?

dannyboy

[drk]

I believe Ilan. I think it's possibly from the IOL he's using, as it's not been noted very often.

[ilanh]

I am fairly sure that the phenomenon is due to the fact that IOL's allow for more than one focal point to exist. Essentially, the light rays hitting the periphery of the IOL may be defocused enough so as to provide a focal plane anterior to the retina ie: myopia or "pseudoaccomodation". This would then imply that monofocal lenses do have some degree of multifocality but not as much as dedicated multifocal IOLs. The issue now arises as to whether this pseudoaccomodative effect would be lost with aspheric IOL's (such as the Technis, Acrysof IQ etc) which are specifically designed to eliminate this peripheral defocusing of light rays. I have used both aspheric and conventional IOL's and will be looking at this issue over the next year as those patients straggle in. If I find that the newer aspheric lenses are reducing this advantage I will certainly avoid them.

Surprisingly, when you try to google this topic you get absolutely nothing (except this thread).

[braheem24]

If I find that the newer aspheric lenses are reducing this advantage I will certainly avoid them.

Keep in mind they still have advantages to those wanting the sharpest distance vision possible.

Surprisingly, when you try to google this topic you get absolutely nothing (except this thread).

That's because everyone else on Google didnt use the ilanh spelling technique :p

[chip anderson]

I have had another dim memory stir. Back before implants and before soft contacts, or even HGP's we would occasionally have a bilateral aphake that could read just fine and have 20/20 distance. In one or two journals this was referred to as "positive aphakic accomodation". I can remember one OMD telling me to caution these patients to never lose such a lens.


For what its worth, there it is.

Chip

[braheem24]

If I find that the newer aspheric lenses are reducing this advantage I will certainly avoid them.

Please update this thread when you finish, I would love to know the outcome of the various IOLs.

Thanks,
Ibrahim

[Bev Heishman]

I am a psuedophake. I am younger than the average cataract patient so we opted for distance correction OU and my surgeon chose AMO Tecnis leneses for contrast. I also have a larger pupil so multifocal IOL's were out.

I should write an article from my perspective through the entire process. Prior to surgery, I had a small antimetropia which I personally felt intolerable at times due to the extensive intermediate and near vision tasks I do. As the cataracts progressed (and quickly) I stabbed my fingers with screw drivers and could hardly see detail. I did not realize what was transpiring until ....

My distance was great after surgery. 20/15 OU except for the symptoms until you scar down. It was wonderful to see how bright everything was with even one eye done. I kept saying WOW on the way home. A lot of POP symptoms reminded me of wearing PMMA lenses in the late 1970's especially in light where the pupil dilates like seeing the edge, flare, etc.. It was even worse wearing glasses even with SAR coatings. My daughter freaked out with the shimmering effect several months POP.

At present, I had a YAG 8 months POP on the first eye. VA returned to 20/15 with J/7 near. My add is +2.50. With correction I am J/1 in that eye. My second eye will need a YAG at 11 month POP. Personally,there is no way I can tolerate even 1 D at near to perform the near tasks needed with out asthenopia and nausea. During the day I am fine with plano correction OU, it is uncomfortable driving at night.

My 2 cents worth from a patient angle.

[Barry Santini]

Personally,there is no way I can tolerate even 1 D at near to perform the near tasks needed with out asthenopia and nausea. During the day I am fine with plano correction OU, it is uncomfortable driving at night.

Interesting observations, Bev. Off topic, in view of what I've quoted above, I wonder what your acclimation is to wrap-around eyewear/sunwear?

Comments?

Barry

[Bev Heishman]

Hi Barry,

I can't handle wrap sunwear even with compensation. I have a large Nine West (Drivewear) and also Kate Spade (Polarized CR39) sunglasses with progressives in them. Now this is an experience! I liked my post-op freebie ALCON overglasses for months. What a fashion statement. The reason was the sideshields.