If both IOLs are set for the same target, is this generally achieved or is the vision in one eye often slightly different than the other? In other words, even if your surgeon aims for the same target in each eye, do you often have inadvertent mini-monovision when all is said and done?
I do, to the tune of half a diopter (so technically, more like micro-monovision). I love the outcome (-2 and -2.5) but I can imagine that if someone is targeting plano and winds up hyperopic, they might not be so happy.
No matter how skilled the surgeon, eyes aren’t machines into which you slot a new part; as the capsule contracts around the IOL, things can shift a bit one way or the other.
The short answer is Yes! You are doing extremely well if the surgeon can hit a target that is within +/- 0.25 D. So if one eye is +0.25 over the target, and the other is -0.25 D under the target then the two eyes will be 0.50 D apart. And, statistics show that only 75% of time are they within +/- 0.5 D.
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That it is why it is very important to only do one eye, and then wait 6 weeks to be tested to find out what the actual outcome is. That outcome will help the surgeon be more accurate on the second eye.
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But, the important thing to consider is that there is absolutely no advantage in having both eyes exactly the same. If they are 0.25 or 0.5 D apart that will improve your depth of focus, and I would suggest having them even more apart than that.
Thanks! Do you have any idea of this is more common than not?
I’ve thought of requesting mini-monovision but you never know how fate will intervene.
I have no idea. But it was a reason that I wanted the same power IOL in both eyes, in case of a shift.
Ron makes a good point about waiting the 6 weeks in between if you can, but in my case the discrepancy between my eyes after the first surgery was too great for much useable vision - I barely left the house and certainly couldn’t drive - so I had them done 2 weeks apart.
If had targeted monovision and the lenses had shifted in opposite directions I might have had more monovision than I would have been comfortable with. Being a very risk-averse person, especially when it comes to my eyes, I opted for the same power in both.
Thanks Ron! That’s good news!
My second surgery is scheduled for 4 weeks out. Hopefully that will be long enough to indicate an approximation of the final result.
Thanks again! How did your -2 and -2.5 results come about? Sounds like you’re happy which is great! Are you wearing glasses most of the time? I would be fine with glasses most of the time with the exception of having to cope with readers. That said, many people feel the opposite!
I have -2 IOLs in both eyes, as I wanted to retain my near vision. I only wear glasses when I leave the house or watch TV; I can do everything else at home without them. I work from home and do a lot of reading (actual books) and computer work, so this has worked out very well for me.
That sounds perfect!
For someone who spends more time outdoors, doing a lot of driving or sports, and who hasn’t been extremely nearsighted since about age 7, this wouldn’t be the right choice. But it was for me. My vision is better now, at age 65, than it was when I was a child.
There is always the possibility of up to 0.5D error due to the IOLs only come in 0.5D steps.
Also there is the unpredictability of the healing of the incision made in the eye to insert the IOL, that can introduce additional error and can add some residual astigmatism.
There is now the new LAL IOLs that can be adjusted with ultraviolet light weeks after surgery to correct any errors, but with the older standard IOLs the result is never exact.
I would stretch the interval to 5 weeks if that is possible, and make sure you get an eyeglass refraction test done of the IOL eye as close as possible to the end of the 5 week interval. Let the surgeon know the outcome, and if necessary they will make an adjustment to the formula used to calculate the power for the second eye.
Some surgeons claim they can reduce astigmatism with the IOL incision location. However I suspect the range that they can do that in is limited. It must be easiest for them to make the incision on the temporal side of the eye.
Thanks Ron! I’ll look into that!
Here in my city, most cataract surgeons seem to wait only two or three weeks.
I also came across this 2021 study from the Ophthalmology Advisor “Cataract Need Not Wait One Month.” That said, Ron is probably right that you get a more accurate refraction if you wait 5 or 6 weeks.
I think some cataract surgery professionals look at it based on their own personal convenience and workflow of the patients through their practice - the quicker the better. To be frank, if the surgeon does not plan to adjust their IOL power calculation method based on the outcome of the first eye, it really does not matter how long you wait between eyes. They could do both eyes in one appointment. They are going to do what they are going to do!
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The only valid reasons for reducing the interval between eyes is a patient consideration. If they have to travel long distances to get the procedure done, they may be willing to risk doing both eyes in one appointment. The other reason is that with very high corrections back to plano doing one eye may result in a big differential between the eyes, and for some that may be hard to deal with. Contacts can mitigate that concern, but many elderly patients are not prepared to use contacts if they have not used them before.
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I think for the bread and butter elderly cataract patient the surgeon probably thinks that they will need glasses anyway, and whether or not they hit the target exactly is not a high priority. For those that want to be eyeglasses free, it is a much higher priority to hit the target. If you want to be eyeglasses free you need to be more selective in who you choose as your surgeon.
“f you want to be eyeglasses free you need to be more selective in who you choose as your surgeon.”
That is exactly right, but I don’t think most patients do that, not just for cataract surgery but for other medical and surgical procedures as well.
Indeed. Being from a family/culture where going only to highly credentialed/recommended doctors at major teaching hospitals is par for the course, I’m always amazed when people just accept the local doc’s judgment without getting a second opinion or going to a major medical center.