Laser touch-up

Many thanks. One eye test found my post op eye is +0.75 sph, -0.5 cyl, another found it was +0.50 sph, -0.75 cyl, but I know the strength can vary over the day, or perhaps eyes are on the border of the two measurements. 

I suppose the priority is whether to request the surgeon to aim at 0 for the next eye?   That sounds safer than requesting 0.5 as it might then come out at -1, which would probably mean wearing glasses for driving, cycling, walking etc.   The surgeon's idea is that I wouldn't need glasses for the above. 

Then after the 2nd eye is done, decide whether to request a very subtle adjustment down for the 1st eye.

The symfony lens sounds great.  I will ask the surgeon whether it is available in the UK and on the NHS, although it would be worth paying privately if there is a high chance of success.

My optician said that multifocal lenses have less contrast (could be a problem reading in dim light) - maybe that doesn't apply to the symfony ?    A friend is happy with trifocal iols, but still needs 1.5 diopter reading glasses, and he basically only needs reading and distance, not the mid - range as I do!

re: "That sounds safer than requesting 0.5 as it might then come out at -1, which would probably mean wearing glasses for driving, cycling, walking etc. "

If your other eye has good distance vision, then your binocular distance vision is likely to still be good. That  is well within the range of monovision many people have who don't wear correction for distance. 

Even for monocular vision for that eye, although studies only give average results since it depends on the person's natural depth of focus and other aspects of their eye, and it depends on the model IOL you got,  typical results would put monocular distance vision for someone with a monofocal IOL at -1D to be 20/40 or even 20/32 or better, so it  might fall into the 20/40 range acceptible for driving even for that eye. What is important is binocular vision, and again that should be good if the other eye is good. 

In my case it was the reduction in depth perception that steered me away from monovision. I'd worn monovision contacts to deal with presbyopia and like them, and not noticed any issues with depth perception as the difference between the eyes increased for a few years. However then I tried multifocal contacts and noticed things seemed more subtly 3D than they had before so I preferered that. However a minor amount of monovision, <= 1D is likely to not have much impact on stereopsis. Since my other eye has at least 20/15  distance vision, I figure even if I aimed for -0.5D and got -1D that it'd still be ok. 

Multifocals do reduce contrast sensitivity. Multifocal IOls are likel better than soft multifocal contacts due to higher quality optics. When I wore soft multifocal contacts I did notice reduced vision in dim light, e.g. trying to see the menu in a dimly lit restaurant I have a weekly meeting at so I was used to what it was like. However I never considered it to be a real problem, I mostly forgot about the issue after I first noticed it. Multifocal IOLs do split light and see some reduction in contrast sensitivity, thought the newest trifocals don't see much reduction, and the Symfony is better than multifocals due to its different optical design that extends the depth of focus rather than splitting it into multiple focal points.

The Symfony was a noticeable improvement in dim light over the multfocal contacts. Its contrast sensitivity is reported in a number of studies to be comparable to a monofocal, and others just show a slight reducton but still better or comparable to age matched subjects with their natural lens. 

Altough its only an anecdotal data point, I know someone here who is about the same age as me who got the Crystalens (and did a long writeup about it), which is a single focus lens which may accommodate a bit, but he sees more of a reduction in dim light than I do. In a well light auditiorum after a talk we met and he held a file folder over a near vision chart to cast a shadow, and it reduced his near by some lines, but didn't change mine a bit. 

 

Its suprising your friend needs readers, most people with trifocals don't. Perhaps 10-20% of people with the Symfony need low power readers, but most with trifocals don't since near vision is where they excel. There is a slight drop off in intermediate with a trifocal (though its still good usually, not as good as the Symfony), and I preferred that since intermediate is useful for computers and everyday social and household tasks, even for where to place your foot on a rocky/icy trail, etc. I figured I could always get readers for the occasional needle threading or other close tasks. 

In my case with the Symfony I have at least 20/15 distance vision (they didn't have a line below that to check and that was easy), at 80 cm its 20/20 plus a bit, and best near is 20/25. At 40cm exactly they didn't have a 20/25 line, so it was 20/30 but I saw some on the 20/20 line so its likely 20/25.

The Symfony is available in the UK, but I'd seen mention the UK only covers monofocals on the NHS. I'd considered going to the UK for my surgery a couple of years ago to get the Symfony.  I'm in the US where the FDA is slow about approving new IOLs and keeps us several years behind the UK and elsewhere. The Symfony was finally approved here 1.5 years after I got my surgery, though we still  don't even have any trifocals approved here. So I had to travel outside the US to get a better IOL, and Canada and Mexico didn't yet have the Symfony.   I wound up instead going to the Czech Republic, where I gather many folks in the UK go for medical tourism.

Google "High rates of spectacle independence, patient satisfaction seen with Symfony IOL" for one   summary of the major study data for the Symfony. Since the Symfony was new when I got it there wasn't much data out, so I keep checking out of curiosity to be sure I placed the right bet, and it all seems to confirm my impression of it. The better near for the trifocal is tempting when I see it, but in reality I don't usually need any more near so the better intermediate makes more sense. One study put the Symfony as having better acuity from 46cms out than the other premium IOLs at the time, a year or so ago I think. 

There is a risk of problematic night vision artifacts with any premium IOL however, a tiny but vocal minority, so there is the need to be prepared for a very tiny chance of a lens exchange with a premium IOL.

 

1. Actually, there is hardly any difference between the 2 readings. For all practical purposes, those are the same. One has usually more variation than that during the day. For example, when you get up in the morning, it is slightly different from what you have later in the day.

2. Regarding the laser enhancement, I have had good experience with that in both of my eyes.

3. If you had your cataract surgery recently, Your right eye is probably still changing changing. You may want to wait until your left eye has also gone through the surgery to make a final decision on your right eye.

4. I have a Symfony lens in my right eye for distance( and a monofocal lens in left for reading).  I have good day vision with the Symfony lens, but have had night vision issue of seeing multiple concentric circles around lights with Symfony lens. I have discussed this issue in my post, "Has Any One Else Noticed this Unusual Vision Issue with Symfony Lens" on this forum. Many other people seem to have had this issue. Rather than repeating that discussion here, you may want to read the comments there.

?2. Perhaps monofocal iols, followed by a laser touch up to bring the left eye's over-correction down to the range 0 to -0.5, and the left eye also adjusted if necessary, is the safest option.  

3. My left eye was had cataract surgery in mid October - might it still be changing ?

4. It does seem as if any premium lens, including the symfony, has some risk of seeing concentric circles around lights at night.  That could be a problem for driving. My optician also mentioned premium lenses give less contrast, although a friend is happy with Trifocal iols, but still 1.5 diopter needs reading glasses.  

5. Am I right in thinking there is a very low risk with a small lasik adjustment, because the degree of thinning involved in the procedure is very small ?

 

I may have been a little confused, but I thought that you have had the cataract surgery in your right eye and are going to have the cataract surgery in your left eye in July. Will appreciate it if you can clarify that so that I am saying the right thing when I suggest any steps.

Have three other questions for you:

1. Which is your dominant eye; right eye or left eye?

2. Are you open to using some amount of monovision, where the eyes have the best focus in slightly different regions? I have had success with this and don't need glasses for reading or intermediate or distance. However, others may have some difficulty in having their brain used to it (it took me about 5 minutes to adjust to it when I first tried it with contact lenses)

3. How important is it for you to not have to use glasses for reading or for intermediate distances?

Regarding your question about LASIK, there should be very low risk of using LASIK enhancement because the required re-shaping of the cornea should be small. Any way, when the time comes, the LASIK surgeon will evaluate that during consultation (which many LASIK places offer free of charge).

Thanks for checking - the left eye was done in October, the right is scheduled for July this year.  

1.The right eye is dominant.

2. I would like to try monovision, but would prefer not to have this with iols as it wouldn't be reversible if I didn't get used to it, would be difficult to work properly during a trial period, and I think a lens exchange might be too risky, as I am very myopic (about -15).   

3. I don't mind using glasses.  My concern is how I will manage focusing on distances from close reading and mobile, to reading music about a metre or yard away.  Varifocal glasses are probably the answer, but they make take time to get used to.  Previously I could read and see in the distance (slightly under-corrected) with a single pair of glasses, and am using my right eye with the old -15 glasses at the moment.

re: 3, usually its only 3 months after surgery before they consider a laser enhancement. In this case though again I'd suggest doing the IOL in your other eye first to see where it winds up. I'd suggest a contact lens trial now perhaps to consider where to target that eye, and whether to go for a premium lens,  then doing a contact lens trial after the 2nd eye is done to decide on level of laser correction.

re: "the left eye also adjusted if necessary, is the safest option. "

It is the lowest risk option in terms of not needing future surgery. Everyone needs to decide based on their own risk preferences.

The risk tradeoff is that a monofocal IOL is guaranteed to provide a lower range of good vision than a premium lens, while there is a tiny risk with a premium lens of problematic night vision artifacts leading to another surgery.  A larger range of vision is a safety issue in that it leads to less distracted time driving when trying to see dashboard or maps, and studies show progressive(/varifocal) glasses reduce reaction time due to the need to move the head and not merely the eyes, and that in the elderly monovision correction or progressives or bifocals lead to a higher risk of falls (due to either depth perception reduction in monovison, or looking through the wrong part of glasses, etc). 

 re: " It does seem as if any premium lens, including the symfony, has some risk of seeing concentric circles around lights at night. "

Yup, though the risk is very low with the Symfony (but unfortunately someone winds up being the "statistic" and posting about it, and some who do seem to have trouble grasping that others really don't have the same problem). Even many folks with monofocals have trouble with halos, they are merely shaped differently, and the odds aren't that much different with the Symfony.

I addressed 4 in other posts. re: 5, yup the risk is lower with smaller corrections.

re: "I would like to try monovision, but would prefer not to have this with iols as it wouldn't be reversible if I didn't get used to it, would be difficult to work properly during a trial period, and I think a lens exchange might be too risky, as I am very myopic (about -15).   "

Monovision with IOLs is reversible with a laser correction. Again, I'd suggest a contact lens trial beforehand (though it depends on how bad the cataract is in your other eye how accurate that would be, and if you are young enough to retain some accommodation in your natural lens in that eye it wouldn't be quite the same). 

If you work at a desk job then monovision shouldn't be a problem, and regardless you can always wear correction over it while working to balance it out while you adapt in non-work time. Most people adapt quickly. I'd suggest its likely harder to adapt to progressive(/varifocal) glasses than monovision. I mostly wore contacts before surgery and only wore glasses rarely as a backup, so I  didn't wear progressives long enough to adapt to them, though I tried to force myself to wear them fulltime for a week or two I think it was to at least be somewhat used to them.

Although its true that a high myope has higher risk of some complications after lens surgery, the risks are still very  low. In fact at least one study suggested that high myopes actually don't have a higher risk of retinal detachment after modern cataract surgery, that they merely have a higher risk to begin with and that the surgery doesn't noticeably change that. Unfortunately some of the data on retinal detachment that serves as scare stories is very old and based on the far more traumatic older generations of lens surgery before modern equipment and techniques. Lens exchange isn't exactly the same as cataract surgery, but not much different aside from the need to chop up the artifical lens, but that is distant enough from the retina that its unlikely to change the stats much.

In terms of halos, I recently ran into this article giving perspective and making me wonder if they should be comparing incidence of halos with phakic eyes in studies and not merely vs. a monofocal control:

"The study, titled Needs, Symptoms, Incidence, Global Eye Health Trends (NSIGHT), surveyed 3,800 spectacle and contact lens-corrected subjects, 15 to 65 years of age, from seven countries (China, Korea, Japan, France, Italy, United Kingdom and the U.S.) to better understand the eye-related symptoms that vision-corrected patients experience. The NSIGHT data provided valuable information on how often patients experience halos and glare and the degree to which they found them bothersome. 

About half of the spectacle and contact lens wearers surveyed reported suffering from the symptoms of halos (52 per cent and 56 per cent, respectively) and glare (47 per cent and 50 per cent, respectively) more than three times a week. More than four of five patients who experienced these symptoms found them bothersome (84 per cent and 89 per cent for halo and glare, respectively). " 

Thanks for the information.

I think that the following straightforward approach may work out best for you:

1. Since you need only a slight change in the presciption for the left eye (you are probably seeing close to 20/20 in that eye right now anyway), you should postpone any laser enhancement in that eye for 5-6 months. By that time, your vision in the right eye also would have stabilized after the cataract surgery. which may affect the best choice for the left eye.

2. There is more than one way to do it, but my suggestion would be to target the right eye for about 40 inches distance (which corresponds to about -1.0 D spherical correction). If that is achieved and you don't have an issue with the slight amount of monovision (most probably, you won't), you will probably be seeing better than 20/25 at distances from 26 inches to far away. If you find that the monovision does not work at all, you can get LASIK enhancement to get the best focus to about -0.5 to 0 D range (just as you may get LASIK enhancement to correct any significant astigmatism or deviation from target, as you are planning for the left eye).

If the above approach works, you will still be using glasses for reading, but that is relatively easier to do.

Thank you.  The range of focus you mention would be very useful.  My only reservation is that, if there is a margin of error of say plus or minus 0.5, targetting -1 diopter could result in being in the range 0.5 - 1.5 diopters. 1.5 would be rather low, and would produce a 1.5 diopter differential between the two eyes.   Maybe targetting -0.5 is a safer option ?    I ought to make another appointment with the surgeon before the operation to discuss and clarify this.

This is just something which you will need to decide for yourself.

Personally, my feeling is that you will be happier with the right eye ending up at the -1.5 (if you were really off by -0.5 from the desired value of -1.0) compared with it ending up at 0. (if you are off by 0.5 from the desired value of -0.5). The former will give you good vision from about 20 inches to 40 inches away, fair to good from 40 to 80 inches away, and good from 80 inches to far away. The later will give you good vision from 80 inches to far away and fair to good from 40 to 80 inches, but poor to fair from less than 40 inches.

In the above message, I should have added that all the distance estimates assume that your astigmatism is low.

It is indeed low:  measured at  -0.5 or -0.75.   I feel subjectively rather 'closed in' by the small range of focus - whether not wearing glasses, or wearing over-the-counter readers.  However, friends say that varifocal glasses are good for everyday use when you need to see clearly at various different distances.

Hopefully, the astigmatism will be small in the right eye too after the cataract surgery..

Part of the reason you have a small range of focus right now is that  you are slightly farsighted. Thus, you are losing all the useful range (typically +0.5 to -0.5 from the nominal value for a monofocal lens) to correct for the farsightedness. If, for example, your needed spherical correction were -0.25 (and there was no astigmatism), you could probably have been able to see well from 53 inches to far away.

I think that if everything works out well, as we have been aiming for, you should not need varifocal lenses because you would be using the glasses for reading only.

Again I would suggest a contact lens trial to see what -1D or -1.5D would be like for you, worst case. Personally for my +0.5D eye, although I hadn't had a contact lens trial, I'd figured I'd likely aim for -0.5D since I'd prefer to be sure it definitely isn't left farsighted, and I'm guessing the margin for error would likely be less than 0.5 for a small correction using modern topographic or wavefront guided methods (I hadn't checked on what is best, or what is viable with a diffractive IOL, I assumed wavefront wouldn't be but I saw something recently that suggests it might).

You mention that "friends say that varifocal glasses are good", I don't know if you might wish to give them a try before surgery if that is one of the factors leading you away from a premium IOL. In my case I was used to always wearing contact lenses, with glasses as a rare backup, so that may be part of why I disliked progressives (/varifocals), since I didn't wear them long enough to adapt to well (i forced myself to wear them for I think a week or two fulltime to try to get used to them for if I ever needed them). You mention feeling "closed-in" currently. In my case that describes how I felt  with progressive glasses due to the narrower field of view for any  particular focal point. If I wore them all the time I may have adapted to them, though I was still only an early presbyope, 49, when I tired progressive glasses and so there was a lower add needed than the high add needed with a monofocal IOL.  That is partly why there is increased risk of falls in the elderly with progressive glasses (which in my case seemed far off, but I figured it made sense to plan for the future, and figuring even low risks add up, if I was comparing the very low risk of needing  a lens exchange vs. the convenience of a premium IOL).

 

 

I think the first decision should be whether to request full distance, or slightly below, when the right eye is operated on this summer.  -0.5 seems sensible, if the margin of error is indeed plus/minus 0.5.    

Meanwhile I could try a -0.5 or -1 contact lens in the left eye as a test, particularly for night driving, which I think is th best way to test distance vision ? 

 

1. The left eye was done in mid October, so should have stabilised now. The surgeon said a laser adjustment to -0.5 might in fact bring it down to -1 then I would be back for a further adjustment up to 0-5, so he didn't recommend adjusting it.  The right eye will be done in mid July.  

2. The distances I need are roughly:

Reading and phone: ?37cm = 15ins

Laptop 43cm = 17ins

Playing piano or organ c.48-53cm = 20ins

Following student's music c.90cm = 36ins

Near full distance for night driving

 

Your plan of aiming for -0.5 for the right eye is as good as any other. So. go for it.

As an additional thought, not doing anything to the left eye at this time may be good for another reason. If you do achieve between -0.5 and 0 with the right eye, then you can try using a trial contact lens in the left eye to get to the best focus at 32-40 inches (-1.25 to -1.). If that works, then you get the laser enhancement to get the left eye to that.

I have made an appoint with my optician to try a contact lens of -0.5 or -1 in my left eye as a test - but have since realised the actual effect will be 0 or -0.5, as my eye is slightly over-corrected from the iol ?   Should I try -1 and -1.5 instead ??

What is your corrected vision in the right eye right now and what are you (or will you be) using in the right eye?

Assuming that your vision in the right eye is 20/20 or so with a contact lens, then for the left eye, you should try a contact lens of +1.5 power (not -1.5) to get the best focus distance to about 40 inches (equivalent to a prescription of -1.0).

The optician tried a lens in my right eye after my left eye op, but the vision wasn't very clear - she thought it was probably because of the developing cataract.  Point taken that the trial lens for the left eye should be +1.5, to be equivalent to an iol prescription of -1.   I think they would have lenses of those powers in stock, so there is no need to ask her in advance.   

If your right eye does not have good distance vision right now, putting a trial contacet lens in the left eye will not be a good test for monovision because none of the 2 eyes will have a good distance vision capability. Thus, it may be better to wait for that test until after you have had cataract surgery to achieve good vision in the right eye.

Just as a minor correction, looking at your prescription for the left eye again, even though your spherical correction is +0.5, the equivalent spherical prescription (because of astigmatism) is closer to +0.25, so that you may need only +1.25 contact lens to get to the best focus distance of about 40 inches.

Thanks - and good to know the left eye is only very slightly over-corrected after the op.

The reason for the left eye contact lens test was not to try out monovision, but rather to simulate the effect of having the right eye aimed at 0.5 when it is operated on.   So to simulate -0.5, I would need to try a +0.75 contact lens in the left eye, and to simulate -1 I would need to try a +1.25 lens?

I've tried +0.75 over the counter glasses, and found them good for full distance and indoor activities eg TV 9ft about away.  +0.5 is good as well.  +1.25 is not good for the above - so taking into account the +0.25 prescription with the iol I guess it is not suitable for the right eye iol prescription.  Incidentally vertical reflections on metal objects viewed at about 10 feet away look markedly 'splayed' through the left eye - I guess because of overcorrection in the vertical plane?  

You are smart in trying out various options..

Trying out +0.75 for the left eye should work, but it is nice to confirm that.

Based on your last prescription, you may also want to try out a contact lens with the astigmatism correction, say, +1.00 - 0.50x170 or -1.00 -0.75x170.

Yes - I have not yet tried the left eye with the astigmatism corrected.    As discussed I would like to try with being under-corrected by 0.5 and 0.75 and 1, but the optician will need to take into account the slight over-correction of my iol and also my slight astigmatism.  Then I will need to persuade the surgeon to aim for slight under correction when he operates - probably aiming at -0.5, producing a result between 0 to -1.

After that, as a separate step, I can see if I can get used to mini-monovision with glasses or lenses before deciding on a laser tweak to reduce the left.

 

I have asked my optician to try simulate, with a contact lens in the left eye, the effect of being under-corrected by 0.5 and 0.75 and 1, before deciding how to target the right eye.

Then I will need to persuade the surgeon to aim for slight under correction when he operates - probably aiming at -0.5, to produce a result between 0 to -1 - I believe the margin of error is plus/minus 0.5, given I am highly myopic !

After that, as a separate step, I can see if I can get used to mini-monovision, experimenting with glasses or lenses, before deciding on a laser tweak to reduce the left, either to balance with the right, or for mini-monovision.

Good plan! Aiming for about -0.5 for the right eye (after confirmation with the contact lens in the left eye) should work

After you have had cataract surgery in the right eye and the vision has stabilized, it will then be a good time to see if monovision works for you with a contact lens and do the needed LASIK enhancement, as needed, to achieve that. If you the target on the right eye, you made need to do the enhancement only on the left eye to achieve the desired monovision.

Many thanks.  This does seem the safest plan as it a) guards against the right ending up over-corrected, and b) allows for a contact lens test to get used to monovision.  As the right eye is dominant, the left is presumably the one to adjust for mid distance, although I do have more floaters in the left, following a retinal tear cryo repair some years ago.

Presumably I would still need to put on glasses for reading, or use progressives with the top part without a prescription?   (That would be  the same as for most folk over 40 who haven't had a cataract op)!