Difference of 1.5 Diopter
Posted , 5 users are following.
Where there is a difference of more than 1.50 diopters between the eyes post operatively glasses are often difficult or impossible to adjust to.
I really don't get it fully! So if after cataract operation the difference is 1.5 diopter then the brain has issues to adjust, I get that. Something to do with the difference is size of the image that the brain is getting.
So is it not an easy fix to use glasses to decrease the diopter difference?
...glasses are often difficult or impossible to adjust to
"CONFUSED" Why????
0 likes, 5 replies
Guest W-H
Posted
It also have to do with the defocus curve.
If you hit plano with a monofocal, this means that plano is at the peak of the defocus curve, giving maximum far vision. This monofocal lens would cover a range from plano to 1 diopter with usable vision, this is the normal defocus curve for a monofocal.
If the second eye is targeted 1.5, this means that 1.5 is the peak of the defocus curve, this lens will cover from 0.5 to 2.5 with usable vision, according to its defocus curve.
This way the lenses will have a small overlap between 0.5 to 1.0 with usable vision and you will feel continuous vision with both lenses from plano to 2.5
2.5 will normally give you usable vision at about 55cm. Maybe even closer with good lighting, and it will also depend a little bit on your genes, some just have better vision than others.
And yes, because of the overlap the brain can blend it together, so both lenses will add vision even in the range where they are not in focus and are not having usable vision on its own.
If there is a gap between the usable vision range within the two eyes, the brain can not blend them together, and you will loose the binocular advantage. So with difference more than 1.5 you can get in trouble, because the overlap will be insufficient.
When you have iols your eyes can no longer accommodate, and you can use whatever glasses you like, and move the focal points to wherever you want to.
So with glasses you can move both focal point to reading vision at 33cm if you like.
Because your eyes can no longer accommodate, in most cases it will not give you headache or make you dizzy and that stuff that you can experience, if you use wrong glasses with your natural lenses, with iols you can pretty much use whatever glasses that fits your liking.
But off course, if you move the focal points closer with glasses, you will no longer have far vision at the same time, because then far distance comes out of focus.
W-H Guest
Posted
So Dr Zeiss recommendation is in green. A difference of 1.4 diopter.
Seems bit risky to me.
Dr Rockstar's was difference of 1 diopter only. Dr Headstand's was, 75 or 1 diopter difference.
I worked at some other combinations that seem more safer?
Guest W-H
Posted
Personally I would go for dr. Zeiss recommendation, and let him do the best job he can, he has done it thousands of times before, I am sure he is not taking unnecessary risks, he knows what he can deliver with the lenses he uses.
Monofocals are not identical, maybe the Zeiss lenses have a slightly more flat defocus curve, then he would be within the same sweet spot like the others. There are many factors I think, and the surgeon knows this stuff, he keeps records of all the surgeries he have done, so he have a very solid statistic basis for his practice.
Off course it has also to do with personality, but personally I would kick myself, if I only got half of the package because I was being too careful.
When the smoke clears and it is all over, and you have a good result but knowing you could have had more without any expenses, I would hate that.
Off course that is just me, what feels right for your wife could be a different matter.
soks W-H
Posted
it is not easy to fix the diopter using glasses because you feel as if you are falling. but that was initially and after sometime i got used to it. iol at plano in one eye and -2.5 glasses in other.
elizabeth87225 W-H
Posted
After my first surgery my right eye had 2 and it needed a 6 and I could not adjust. I was seeing double besides the other problems probably due to the lens position. It seems my eyes were competing for control and since the incorrect lens was on the dominant eye, I would see double in one image. It was scary. I went to get corrective lenses and I was given an example of what I could see if I tried glasses...It was horrible, it did not do the job. So after 6 months of disaster I had an IOL exchange. That worked so far.