What questions should I ask my surgeon in determining the best range of focus for my IOL?
Posted , 7 users are following.
I had a consultation that that left me completely unsure of what to expect. I have a cataract in one eye. My vision is -3.5 according to my contact lens prescription. I told him that I wanted a lens that would enable me to read and use the computer without the aide of glasses. He suggested a near vision IOL (the standard kind because that's all my insurance will pay for). If I recall correctly, I asked him a couple of times to specify what kind of vision I can expect, but he never really gave me a clear answer. Later, I was kicking myself for not being more direct.
A few days go by when I decided to reach out to him, but he'd taken the rest of the week off and wouldn't be back until my surgery date. Yikes! His secretory tried to assure me that I'd be able to see at "arm's length," but what does that even mean? Will objects be clear from 3 inches away and will they remain clear at 30? I ended up rescheduling my appointment in the hopes that he will call and clear this up.
Question 1. Am I being unreasonable in asking him to call for a few minutes? I just want to know what to expect.
Question 2. What exactly should I ask him. Should I just ask, "what will my field of vision be" or are there better, more precise questions to ask? I appreciate any advice.
0 likes, 11 replies
RonAKA n62983
Edited
No you are not being unreasonable at all. A cataract surgery should be a once in a lifetime event for each eye. It is something you want to get right and be aware up front what the outcome will be.
.
Surgeons work in diopters as a target. That is what they punch into the computer program to determine the power of lens to use. To put things in perspective a bit when you get progressive or bifocal glasses the almost standard addition to give you near vision is a +2.5 D. When you have full distance vision and a +2.5 D add is made to your glasses that effectively makes you -2.5 D near sighted or myopic. Most people find that excellent for near vision reading. A little more than that would be -3.5 D or what you seem to have now without your contact in. As you must know, however when you look up and into the distance with that amount of myopia things are pretty blurry, which is why many choose a progressive lens in their glasses. Then the -2.5 D is the power at the bottom of the lens and as you move up the add progresses so there is less and less until you are at 0.0 for add at the top of the lens. I have both eyes done with basic monofocals, but I have had one eye done at -1.5 D to give me closer vision. It is not as powerful as the -2.5 D, but it still gives me pretty good close vision. I can see my computer well and even read my iPhone, and any standard text document. The TV at 7 feet away or so is pretty clear but not perfect. For very small print and especially in dimmer light I need to use some +1.25 readers.
.
So what do you ask the surgeon to target? You know with your natural eye what -3.5 D gives you. That is probably a bit much. -2.5 would give you standard close vision as used in eyeglasses. -1.5 will not give you super close vision, but I find it quite acceptable close vision. My other eye is corrected to give me full distance vision. Between the two eyes I can see from about 10" out to full distance without glasses. Why would I not go with -2.5 D for even better closer vision? Well it is because the large majority of people can handle a difference of 1.5 D between the eyes, but most don't do so well with a differential of 2.5 D, although that has been attempted in the past, but has fallen out of favour. A differential of 3.5 D would be really tough, but you will know what that is like now when you don't have a contact in that eye, but do have one in the other eye. You also can easily simulate a differential of 1.5 D by using a -2.0 D contact in your eye that requires -3.5 D. That will will leave you -1.5 D under corrected or myopic. This will be a reasonable simulation of what you will see if the surgeon targets -1.5 D in your cataract eye. And down the road you will have the option of targeting the second eye for full distance correction, and be essentially eyeglasses free. This works very well for me, but not everyone is sold on it. However for you, already wearing contacts, all you need is a trial sample of some -2.0 D contacts to give it a try.
.
You can of course go for -2.5 or -3.0 but when you go down that road, you are kind of locking yourself into needing eyeglasses for distance.
.
But for sure don't get rushed into a decision. Give yourself some time to make a thought through decision and ideally by testing it with contacts.
n62983 RonAKA
Posted
Thank you!
MsJ101 RonAKA
Posted
Ron, you're so good with these numbers. Let me ask you, what would you say the practical observation would be of having your distance IOL at -1.0 instead of plano? What does that really mean when visually scanning a landscape or farther distances or while driving? Is there a literal number of feet that equates to, or is there an amortizable (?) effect, for lack of a better term. Thanks!
RonAKA MsJ101
Posted
If you target -1.0 D with a standard monofocal your distance vision will be about 20/40. That is an average of a number of people, and your result could be a little better or a little worse. In most jurisdictions 20/40 is the minimum distance vision you need to get a driving license without an eyeglass restriction.
Spring1951 n62983
Edited
I have been trying to get the same answers for about two weeks now! It seems some of the Surgeons do not like to be pinned down with that question. In fact today, I wrote my doctor again asking for some idea of what I will be able to see after the monofocal intermediate IOL's are put in!! I gave her two scenarios to choose from even. I even called twice and asked for another tel. interview which they did set up. I have asked her over 3 times for an answer but never seem to get one. She sent me an article which was complex and didn't answer the questions but did give me a vague drift of how it works! One person I ran into said his monofocals in his near eye rendered good vision from about 13 inches to 53 inches and he has a distance monofocal which takes care of the rest. That is the only time I have seen anything that detailed listing an actual measurement that I can relate to! Anyway, good luck, keep persisting and you might get the information that you need. I honestly think I am going to get an answer when I speak to my doctor since she cannot escape at this point!
n62983 Spring1951
Posted
Thank you so much for sharing your story! I thought that I was the only one! It's incredible that you went through all of that trouble and still haven't gotten a simple and direct reply. I wish that they would say, "you'll be able to see clearly from distance X to distance Y. Anything before X and anything after Y will be out of focus." Then we would at least know that we've made the right choice based on our needs.
I'll say this a as a complete non-expert be careful if you're getting two different lenses to cover both near and distant vision. If they're too different you may find it hard to adjust. Some doctors even offer contacts to simulate the experience before having the patient commit to them. Again, I'm just learning as I go and relaying what I've read. This is just a head's up from a complete novice. I wish you the best!
RonAKA n62983
Edited
Perhaps this graph will give you a better idea what the options are. You can ask for different outcomes for nearer vision. This graph shows the quality of vision from 4 different options on the vertical scale. The horizontal scale is the distance in meters. The one option called Dominant eye is the outcome if you get a full distance correction. It is normally done in the dominant eye. Visualize a horizontal line at the 20/32 level. That is the limit of what is considered good vision. The other three lines are options for a nearer vision eye, that show the level of vision for increasing amounts of myopia; -1.0 D, -1.5 D, and -2.0 D. As you can see there are no hard drop off a cliff points, but they do hit the 20/32 vision points at various distances. If you look at each curve you see at what distance the line intersects with the 20/32 vision level. For example the full distance lens option intersects at about 0.75 meters or a little over two feet. You can do the same with the other lens options.
.
.
Then if you put a distance lens together with each of these near vision options you get curves like this which illustrates the combined vision with each nearer eye option. This is from a study that concluded the optimum amount of myopia in the near eye is -1.5 D.
.
soks RonAKA
Posted
the problem is the high diopters and narrow range it takes for near vision.
RonAKA soks
Edited
I am not sure what you mean by that. My nearer eye is about -1.40 D and I have very good near vision in that eye from about 10" out to 6 feet or so, and also 20/20 distance vision in my other eye. My only issue is that my nearer eye is at -1.0 D sphere, and -0.75 D cylinder. This combines to give me about -1.40 D. However, I am sure my near vision would be much clearer if I was simply -1.5 D sphere. And in fact -1.25 might work well too. That was my initial choice for a target.
.
I had counted on reducing that cylinder with Lasik, but it has turned out not to be possible. They can reduce the cylinder, but cannot increase the myopia up from -1.0 to -1.5. It is easy to make the cornea flatter, but very difficult to make it steeper.
Spring1951 n62983
Posted
Yes, you are right about mini-monovision and using two different lenses to cover both near and distant vision. Some do find it hard to adjust and it is a good idea to test with contacts. I am glad I could offer you my own experience with trying to get the same information from my doctor that you are seeking which I would think most people would want. I am still working on it and I think I am getting closer to getting an answer! One thing that may be hard to predict, however, is how similar are the natural lens which has lost flexibility with aging and the monofocal lens which doesn't have flexibility except in the focal area and then adding in the removal of astigmatism in the lens as well as cataract removal.....what does that all tally up to in terms of the "new vision" after the monofocal IOL is put in? Maybe that is hard to gage for the Ophthalmologist?
jimluck n62983
Edited
The doctors are evasive on this question because they don't know. My doctor emails with me freely. He is direct about it: He can't predict how much depth of focus a given patient will have. Corneas vary in ways beyond the power of their instruments to analyze.
I am very myopic (-6 or -7) and hugely astigmatic (-8.25 and -2.25). I use the computer a lot and was very unhappy with progressives. The doctors thought it was my cataracts. Finally I asked for trial lenses and sat at the computer holding different powers in front of my glasses. I determined 0.75 diopters of myopia was perfect for computer for me at about 21 inches. I had them make single vision glasses with that prescription and find that they are good for everything from driving to phone use. Yet I am 73 and have cataracts.
No eye doc could have predicted that.
Next I tried scleral contacts which automatically correct all the corneal astigmatism giving me the vision of perfectly spherical corneas. Vision is super sharp, but only at one distance. My fabulous depth of focus shrinks to nothing.
Corneas vary in ways too difficult to analyze . So no doctor can predict your depth of focus. They can tell you averages but what good is that? You are going to have one outcome, not multiple outcomes you can average.
I also got glasses that make me -2.0 myopic. For many people that would be good for the computer. But I can't use them with the computer. They are great for a book at 12 inches or so, but the computer screen is too far away. I almost never use them because the 0.75 diopter myopic glasses also work for a book so why bother switching.
For tiny print I just take off my glasses and close the 8.25 cylinder eye.
I am trying minimonovision with the contacts now at plano and -1.5. It works great for computer, but for distance the -1.5 eye's blur bothers me. For close , I have to use readers. So it doesn't give me as much depth of focus as my 0.75 myopic glasses. Way less.