We now have excellent predictability with IOL calculations and a variety of techniques and multifocal IOLs to help give our patients their best functional uncorrected postop vision. We need to customize the target refraction for each patient depending on their visual needs. Dr. Downing will discuss the advantages in many patients of monovision or mini-monovision to minimize their need for spectacles if they want to see well without glasses as much as possible and are not good candidates for multifocal IOLs.
Lecturer: Dr. John E. Downing, Kentucky, USA
DR Downing: Good morning. I’m Dr. John Downing. I’m talking to you from the United States.
I’m gonna talk this morning about ways of correcting presbyopia, primarily with cataract surgery. We’re going to start off giving you four questions. If you would please write down your best answer for each one, then we’ll do the presentation, and then after that, we’ll present the questions again and discuss the answers.
So we’ll start with the questions. This is question one. Do most postoperative cataract patients prefer to be left slightly hyperopic, slightly myopic, moderately myopic, or emmetropic? Mark which one you think is the most likely.
Now let’s go to question two. At what level does residual astigmatism begin to cause blur? 1 diopter, half a diopter, 1.5 diopters, 0.25 diopter? Put your best answer there.
Okay. Question three. How much difference in refraction between eyes, anisometropia, begins to cause symptoms? 1 diopter, 1.5 diopters, 2 diopters, or 2.5 diopters?
Question four. In what patients should you generally not use multifocal intraocular lenses? Patients with dry eye syndrome? Corneal dystrophy? Macular degeneration, or all of the above?
Okay. Well, let’s talk about correction of presbyopia with cataract surgery. Presbyopia is the scourge of middle age. Generally for most of us, it’s a reminder that we’re getting older. When we notice that we can’t hold things out far enough to be able to see them very well at near. At this point, low myopes have an advantage. They can take off their glasses for near and just use them for distance.
Once you’re presbyopic, some myopia is a benefit. And if you are in your 40s or later, I think you probably would agree that you didn’t really think presbyopia was a big deal, until it happened to you. Then it becomes a very big deal, usually. We’ve tried many treatments. There have been ocular surgical procedures, ciliary body expansion to increase the length of the eye a little bit, corneal inlays of several types, nothing has worked very well. I also have tried multifocal Excimer corneal treatments. Those have not worked very well to this point. Most of us just end up using reading glasses. And if you’re emmetropic and have been for your 45 or 50 years, you don’t have any idea how much trouble presbyopia is, until your arms start getting too short, if you have any kind of near work.
If you’re not emmetropic, you’re gonna go ahead and have to get bifocal or multifocal glasses. If you’re very near sighted, a lot of patients in the United States at least wear contact lenses, and many of them, once they become presbyopic, will use monovision, where they correct their dominant eye for distance and the near eye will undercorrect it to leave some myopia, and that works very well for many patients.
It doesn’t for everybody. The most recent and probably the best overall for many patients is multifocal intraocular lenses. They keep improving. They have advantages and disadvantages, but they are becoming more workable. Okay. Eventually, most of us develop cataracts. And it’s now possible for us to give many cataract patients good functional near and distance vision with cataract surgery and intraocular lens replacement.
Multifocal glasses work fine for many people. A lot of patients do not mind wearing glasses, but they don’t work well for some people. Particularly farmers, people who work out in the rice paddies. Glasses are a real problem. Each way we have currently of correcting presbyopia has strengths and weaknesses. We’re talking now about multifocal intraocular lenses. What we have available in the US are pretty limited, compared to what most of the rest of the world has.
We have the Restor, apodized bifocal, Technis has a diffractive multifocal, AMO has an extended lens which they call the Symphony, and we’ve recently been able to use Panoptix trifocal lenses, the first trifocal lens that’s been approved in the United States. I know from reading the literature there are a number of trifocals that are being used in different parts of the world, but our government has been a little slow to approve them.
And the other current way that we can correct is monovision after cataract surgery. Now, when you’re considering cataract surgery, you need to consider each patient’s individual visual needs. Do they need to see well mostly at distance? At intermediate? Or near? And most of us would like to have at least some useful vision at all distances. I have to ask people: Do they mind wearing glasses? Do they have glasses available? And are glasses practical in their occupation?
If people have to work out in the hot sun a lot, they have a lot of problems. Okay. You can correct presbyopia in some ways with monofocal lenses. We’ve had monofocal lenses for about 60 years. They constantly improve them, bit by bit. They’ve had many changes in design. Basically, there are those with spherical optics and those that have aspheric optics. Also lenses that are designed to be placed in the anterior chamber or in the ciliary sulcus or in the capsular bag.
And monofocal lenses give you good, sharp focus at their focal point. But about 10% of them have some glare or dysphotopsias. However, if you ask them, people with cataracts have dysphotopsias too. Particularly glare. Almost all people need glasses some or all of the time if both eyes are focused for distance with monofocal lenses. I’ll talk a little bit about what presbyopic lenses that we have available in the US — the Crystalens has been around for a good number of years.
It’s monofocal, it is said to be pseudoaccommodative by moving in the eye. It has a hinge. However, there’s little or no near distance change in most patients. So it’s not being used a whole lot. We have a variety of multifocals. They are all apodized, it’s called. Or they have different focal points, by having little ridges on them, and the Restor and Technis both are basically bifocal lenses. We have the Panoptix, which is now a trifocal lens, and we have the extended range of Focus lenses,
which are the — the trade name in the States is the Symphony. The Symfony works by correcting some chromatic aberration. Works well generally distance at intermediate. It does not give as good near vision as the bifocal or the trifocal lenses. Generally. This is just a picture of the Crystalens. Showing the hinges, which… Were designed hopefully to flex forward with the change of the anterior chamber effective depth. It works fairly well in high powers. Does not work well at all in low powers. I’ll occasionally use a Crystalens in patients with media or retina problems, but they almost always still need reading glasses to read small print. With the Crystalens, it generally works best to aim for plano in the dominant eye but make them a little bit nearsighted, 0.35 of a diopter, in their non-dominant eye. You can consider it in early AMD or soft drusen, superficial corneal dystrophs, or other media problems, because they’re a monofocal lens. You get away from the aberrations and dysphotopsias that you get with multifocal lenses. All the multifocal lenses we have in the United States use diffractive optics. They divide the incoming light into multiple wavefronts with small steps on the optic surface which can be designed to produce two or three sharp focal points by wavefront interference.
They all lose a significant amount of light. You always get circles around lights, which most people adapt to or don’t notice after a while. Something you need to know is that the multifocal lenses have a posted power, but their effective add in the eye is about 20% lower than stated. So that’s for instance if the posted power is 3 diopters, the effective power in the eye is about 2.4 to 2.5.
And both Alcon and Tecnis, which are the major companies we have available, have effective adds of 3, 2.50, or 2. The extended range of focus lens, the EFIOL, is the Symfony. That gets good results at intermediate vision. Typically people still need reading glasses for very small print. Depends how much they do at near. And they still get the multifocal aberrations of rings around lights and some glare.
Now, all the multifocal lenses or contacts have some loss of contrast sensitivity, sharpness, and loss of effective light. They all have rings around light, they all have some glare. Fortunately most people adapt to those. Their brain stops noticing that, usually, after several months. But not always. On the left, this shows you the sharpness focus at distance. With a monofocal lens. On the right is with a multifocal at distance.
And things are just a little bit fuzzy. And most people adapt to that and don’t particularly notice it. Many multifocal patients read 20/20 distance and near and are very happy with them. The only trifocal lens that we have available, as I said earlier, is the Alcon Panoptix. We’ve only had it for a few months. It has good distance, intermediate, and near vision in most patients. I know a lot of you have other lenses available outside the US.
And there are some experimental lenses, which do accommodate, but none of them that I’m aware of has made it to market. Most people are not all that impressed with vision after you do their first eye with a multifocal lens. But usually they’re getting a lot of improvement after the second eye is done, and they can focus together. And you need to stress that their vision can improve for six months or longer as their brain adapts.
We call it neuroadaptation. We’re not sure how it happens, but it’s real. Okay. When would you might want to use a multifocal lens? Good patients are those who hate to wear glasses or don’t have glasses available. Have reasonable expectations. They don’t expect perfect vision. They know they’ll have some aberrations like circles around lights. And you want to stress that they’ll decrease your need for glasses,
but you still may need glasses at times. Best patients to start with by far are hyperopes. Hyperopes don’t see well at any distance without correction. And they are thrilled to be able to see even reasonably well, distance and near, without glasses. You have to have patients that either have less than half a diopter of corneal cylinder, or you can treat it so they end up postoperatively with less than a half.
Or they get unacceptable blur, usually. You want patients who have normal corneas, medias, and maculas. Normal tear film. Dry eyes are a major problem in post-op complaints. If you miss dry eyes and are not treating them, they will not usually get very good vision. The big problem is that they’re expensive and many people cannot afford them.
Okay. Who should you not do multifocal lenses in? People with corneal problems. Dystrophies, anterior, posterior, keratoconus, forme fruste keratoconus, pellucid marginal degeneration, dry eye, or if they have more than 0.50 corneal cylinder unless you can correct it. Retinal problems. Early ARMD, PRM, if they’re diabetic, or if they have cystoid macular edema for any reason.
Low myopes generally are not happy with multifocal lenses. In the range of a -1 to -3, they are used to just not using glasses for most things, for most people. And using glasses for distance for things like driving. They won’t get as good vision postoperatively with a multifocal lens at near as they are used to. And most of them want to be left as low myopes, postoperatively.
So you need to ask. Low myopes: Are you happy with the vision you have? Do you mind wearing glasses for distance? And if they don’t, I’ll generally aim pretty much for what they were preoperatively, so that they wind up that way postoperatively. If you change them, they will not like you. They will be unhappy and it’s not a good thing. They have zonular bag defects, pseudoexfoliation, any kind of bag problems like that,
you should generally avoid them. The lenses sometimes won’t center well. And you need to avoid demanding or picky patients. Particularly patients who are engineers or professional folks. Now let’s talk a little bit about monovision with intraocular lenses. You can get fair to good distance and near vision if you target the dominant eye, plano to -0.5. I almost always target the dominant eye to about -0.5 with monofocal lenses.
The reason is: Our predictions are getting better, but we can still only get 80-some percent within plus or minus 0.5 diopter of predicted. And you do not want patients to end up hyperopic postoperatively. They have to wear glasses or contacts all the time, and we can do a lot better now. For regular monovision, you target the non-dominant eye between -1.50 and 2. They effectively have a diopter or so of depth of field.
So you can get the effect of about 2.5 diopters or so of near add, particularly with good light. You have to discuss the pros and cons, pre-op. That you can generally get good distance in intermediate vision. People who have used monovision with contacts generally like it postoperatively, but they often are gonna need bifocal correction for driving to get a little better depth perception at distance or at night.
And it helps if they both focus together for prolonged near work. And again, contact lens wear. If they’ve used and liked monovision, they generally do better with that than they do multifocals. Ask anybody who is myopic, who is wearing contact lenses, have you had one eye focused for near and one eye focused for distance? And the large majority in the United States at least have. And that’s — if they’re happy with it, keep them there.
Okay. So what kind of vision can you get with monovision? There’s called mini-monovision, which is about a diopter of myopia in the non-dominant eye. Usually you can get about 6/6 or 20/20 for distance and 20/40 for near, uncorrected. Full monovision can usually get 20 to 25 distance and near uncorrected. May not ever need to use glasses. But many do wear glasses part-time for distance. Like for driving.
Many monovision. I frequently target the dominant eye at about -0.5 and the non-dominant eye at -0.75 to -1. If you do not explain why you’re doing it and demonstrate postoperatively that they see well at near with one eye and much better at distance with the other, they’ll think you just don’t know what you were doing.
But if you demonstrate that both eyes together, they have a much better range of vision, and generally don’t have to wear reading glasses nearly as much… I have had personal experience with cataract surgery. A little over a year ago. I got to the point where I was getting terrible glare at night. I wanted to go with a multifocal lens, but I had a problem with my cornea. I had some anterior and posterior corneal dystrophy.
And moderate to severe dry eyes for many years. I didn’t think I was a good candidate for multifocal intraocular lens with that. I had tried monovision with contacts. Didn’t really like it. Did want some near vision. So I decided on mini-monovision. Let’s go back. And I have been happy with it. I’ll explain that a little bit more in a few minutes.
Now, if you’re doing a preoperative workup, and trying to decide which way to go with people, particularly for multifocal lenses, you need to have patients where you have a good history, reasonable expectations, look for dry eye and lid problems, you have to do very careful biometry. For multifocal lenses, you need to be able to use laser measurements, IOLMaster or Lenstar in the states. Applanation, A-scan, is not adequate for calculating multifocal lenses.
You will end up with a lot of them who are significantly myopic because of corneal indentation. You can use immersion A-scan, and that is adequate enough, probably. You need to do topography, evaluate how much corneal astigmatism or irregularities they have. If you think they have a retinal problem, it’s a good idea if you can do a macular OCT. And again, evaluate their tear film.
With multifocal lenses, you want to avoid, again, low myopes, -1 to -3, because their near vision is not going to be as sharp as they are used to. Patients with corneal or retinal problems. Poorly controlled dry eyes. People who like to drive a lot at night or have to drive a lot at night like truck drivers. Because they get distracting rings around lights. And you want to avoid hypercritical patients.
You want to avoid — or fix corneal cylinder above about 0.5 diopter. There are multifocal toric lenses. They’re a little bit more expensive, but if these patients can afford them, they’re certainly a good possibility. You can correct corneal cylinder. Low amounts with relaxing incisions. Or if you have it available, LASIK or PRK for any residual postoperatively.
You need to take time to explain the pros and cons of multifocal lenses. Tell them they can markedly decrease their need for glasses but not usually completely eliminate them. That they lose some sharpness and contrast. They can usually get good distance and near vision, but they have glare or halos, which do usually get better over time. They still may need glasses at times.
Many people do report never needing glasses postoperatively, with multifocal lenses. But just tell them they can probably do most tasks without glasses. If you tell them that some people don’t have to wear glasses postoperatively, if they ever have to, they’ll think they’re a total failure and that you messed up. You need to find out what near tasks they want to do.
Do they read a lot? Do they work mostly at intermediate, on a computer? Again, a lot of them work better bilaterally, because you do get binocular summation and neuroadaptation, but it may take time. Okay. My experience is that my multifocal patients generally have been happy. I’ve only had to remove a few. And one way, if they’re thinking they’re not happy,
check their distance and near vision, and then while they’re holding a near card, hold up a couple of -3 lenses in front of them. And say: This is what you would see if we changed to a monofocal. And remove them and say: This is the improvement you get because of getting these fancy lenses. I do like the trifocal multifocal lenses.
You have to be right on with your power calculations. And be able to control astigmatism. You have to have a plan to correct if your calculations are wrong and they have residual. I have done PRK or piggyback lenses on a few patients. I’ve had two or three patients over the years that I had to remove the multifocal and put in a monofocal, because their brain just could not adapt to the double images.
Centering a multifocal lens is important. I usually rotate it vertically. And you want it to be just a little bit nasally. Remove all the viscoelastic in front of and behind the lens. So it doesn’t move after you’re finished. And then place it slightly nasally. And have them look — dim the microscope light. Have them look at it. And center the rings on the light or slightly nasally.
Postoperatively, they have patients who have blurred vision. This is again multifocal lenses. Okay. Blurred vision usually gets better after the second eye done. If you’re on with your power and astigmatism correction. Dry eye, again, is very important. Important to treat. If you have a power error, you’re going to have to address it when they’re stable. Generally, wait two or three months.
Because you need a spherical equivalent of plano with no more than half a diopter of cylinder for best vision. You have to treat any residual astigmatism over that. And give the brain time to adjust. These patients can take a lot of time. Now, if they saw well for a certain period of time, months or years, and they come in with decreasing vision, you have to make sure it’s not a retinal problem or dry eye.
That they do see poorly, if they get small amounts of posterior capsule opacification. But make sure there’s not another problem before you open the capsule. If it’s a problem where you might eventually need a lens exchange, do not open the capsule. That greatly increases your risk — or their risk — with lens exchange. Look at their macula. Make sure they haven’t developed problems there.
And it’s possible that you made poor patient selection. People who are hypercritical and crazy, either you or the patient for doing it… I unfortunately have one like that, that I’m nursing at the moment, that I probably should not have done. I’m sorry. Let’s go back up. I’m missing a couple of slides about my experience with mini-monovision. So let me tell you.
Mini-monovision — I expected to see well for distance, and I expected about 20/40 for near. I have done much better than that. I see 20/20 at distance. I see 20/25 at near uncorrected. And I only need to wear reading glasses for prolonged reading or very small close work. I’m very enthusiastic about monovision, either full monovision or mini-monovision. I think you can greatly decrease people’s need for glasses, just using monofocal lenses,
without costing them a lot of money. Okay. Let’s go through the questions again. And we have question one. There we go. Most postoperative cataract patients prefer to be left: Slightly hyperopic, slightly myopic, moderately myopic, or emmetropic.
Okay. Let’s see what your answers are. Okay. 96% said slightly myopic. I think you’re exactly right. Okay. Question two. At what level does residual astigmatism begin to cause blur? 1 diopter, 0.5 diopter, 1.5 diopters, 0.25 diopter?
Okay. Let’s see your answers. Okay. Yeah. Half a diopter or more begins to cause some blur. 0.75 of a diopter or more definitely does. So 1.5 diopters, they’re gonna get a significant blur. 1 diopter, they will get some. But you want to try to have 0.5 diopter or less.
Okay. Let’s have the next one. How much difference in refraction (anisometropia) begins to cause symptoms? 1 diopters, 1.5 diopters, 2 diopters, 2.5 diopters?
Okay. Let’s look at the answers. Most people will notice it at 2 diopters or more. That’s right. That’s good. Because you get an image size difference and it’s hard to fuse. Question four. In what patients should you not use generally multifocal lenses?
Dry eye syndrome, corneal dystrophy, macular degeneration, or all of the above?
And the answers. Exactly. You need to be very cautious with multifocal lenses. People who are good candidates. And particularly who hate to wear glasses generally will do very well with them. The ones that are not good candidates and have problems can take up an awful lot of time and effort.
Okay. Now, we had some questions before that were put in. Okay. Whoops. I think… We have specific surgical correction… I’m sorry. How early can we intervene in patients who are myopic or hypermetropic? Generally want to have people who are having significant cataract symptoms. Glare, blur, difficulty with tasks that they need to do. There’s no specific number. It just depends, I think, more on symptoms than anything.
Possibilities to avoid glasses after this? Yes, several. Mini-monovision, monovision, or multifocal lenses can all make people largely glasses-free. What do I do about astigmatism? Make sure what the corneal astigmatism is preoperatively. Sometimes there’s not good correlation between refractive and corneal cylinder. You want to try to correct the corneal cylinder. Because you’re removing the lens with any astigmatic change it has. Which is often significant.
My opinion about extended depth of focus lenses? I have not had very good luck with them. I have had good distance and intermediate vision, but a fair number of complaints about near vision, and people have had to often wear reading glasses a lot. How to make people glare-free. If you get out the cataract, that often helps a great deal with glare. Took care of mine completely. And I was blinded driving at night,
before I got up the courage to have surgery. Surgical options in terms of laser keratoplasty, for successfully treating presbyopia? Not that I’m aware of. Patient satisfaction, brands of available lenses that can be used… All the lenses that are available currently I think are good as far as optical qualities. You even just may have to pick different lenses for different fixation needs.
Best option for presbyopia correction? That depends on the individual patient and what their needs are for distance, near, and intermediate vision. But people do generally do most of the things that we do now at near, so it’s a great deal of help to have some near vision. In my case, I’m 20/20 distance, 20/25 near without glasses. If I correct my non-dominant eye, which is -1, my near vision binocularly drops to 20/70. That’s not very helpful.
People with presbyopia often don’t want to have surgery. In India. How can we increase their awareness? Generally once they get enough cataract that they need to see better, the majority of people will eventually decide to have surgery. Now, this is changing tremendously. I have seen that over the last 30 years. The way that we could correct cataracts when I started this was with glasses. Aphakic glasses and no intraocular lenses.
As we got intraocular lenses and people began to see that people got good vision with them, that just greatly increased people’s willingness to have surgery earlier. And I think we can continue to do that. By doing good surgery. Happy patients who see well are our best advertisement. And the best salespeople for other people to get surgery.
Okay. If a -5 diopter myope wishes to have intermediate clear and near vision, what kind of intraocular lens would I suggest? I think we went through that pretty well. Your choices are multifocal lenses — again, the trifocal has worked best for the multifocal lenses I’ve seen. Monovision or mini-monovision work well in many people.
Is there a method for correction of presbyopia with laser? Not that has been proven to be useful, as far as I’m aware. Any other questions?
What about halos and multifocals? They all have some halos. You need to tell people that. In almost all of them, unless they get fixated on them, they will get less over time. And if you tell them… Yes, that’s normal. Show them the advantage of the multifocal, by showing them what they would be able to see at near without it. With -3 lenses.
And try to have them be patient. Most of them are happy. What’s the difference between spheric and aspheric? You get peripheral aberration in high plus lenses. And our eyes have some spherical aberration. The aspheric lenses — minus aspheric lenses, which are mostly what are used now — give you better depth of field. And a little sharper vision. Can I explain more about monovision planning?
Okay. I have people who… Someone who has significant cataracts in both eyes. Find out what their visual needs are. Most of the time, they need to be able to see fairly well at near. If they are not good candidates or can’t afford a multifocal lens, I would explain to them about making their non-dominant eye a little bit nearsighted, and that does give them a much better range of vision.
That if they’re going to do very detailed close work for any period of time, they will need reading glasses, but that can greatly decrease their need to wear reading glasses all the time for close work. How do you decide which is the dominant eye? A number of ways. You can stand 15 or 20 feet away and just have them point. Hold up your finger. Have them point to your finger. And see which eye lines up with their finger.
I use a card which has a hole in the center. I have them hold it out. At arm’s length. And look at my finger. Or look at me. With both eyes open. And then bring the card in, until it’s against their face, and they’ll bring it in to their dominant eye. Those are two good ways. There are a number of others. Do ophthalmologists ever choose multifocals for themselves? Yes. I would have, if I had had a good cornea.
They are good enough now that I definitely think they work well in people who want to be glasses-free as much as possible. Particularly with the new trifocal intraocular lenses. Okay. The advantage of the trifocal intraocular lens is it gets decent intermediate vision, and a lot of us spend a lot of time on computers or other things at arm’s length. With the bifocal lenses, with usual add of 3, which actually is about a 2.5, effectively, they get generally good distance and near vision, but there’s an area in intermediate arm’s length vision that’s not quite clear. They either have to get further away or closer. So I’m just currently using the trifocal lenses in people who want multifocals. Do I measure pupil size when I do multifocals? Not usually. No. I measure pupil size in people I’m going to do laser corneal correction refractive. But not in patients with intraocular lenses.
We note it, but don’t usually measure. Okay. If mini-monovision patients need to use near add glasses, they generally do fine just with over-the-counter readers. Correction. With prescription works a little better. I have both. And I’m a little bit clearer if I use my near correction in each eye. Good question. Okay.
Okay! Well, thank you very much. I hope that’s been useful. Think about monovision. Try not to leave people hyperopic. They’re gonna be much happier if they have some near vision. I have been amazed how much near vision I have just with a -1 under correction in my non-dominant eye. Thank you.
January 17, 2020