monovision

[shamir]

One week ago I  had a cataract surgery with my right eye with a monofocal IOL. Before surgery my right eye was short sighted  – 8 diopters and now it is short sighted with – 3 diopters. I can now read with the right eye without glasses. My left eye is short sighted with -8.5 diopters and 1.5 cylinders (astigmatism) and it has cataract. Next week I shall have a new surgery for the left eye with a monofocal IOL. Assuming that this IOL would give perfect correction for short sight (0 diopter) so I would have good vision with the left eye for far sight without glasses, shall I get a good quality monovision without glasses? My surgeon thinks that the 3 diopters difference between the left and the right eye might be too high for good quality monovision and that a difference less than 1.5 diopters would be much better.
Assuming that there might be a monovision problem because of the – 3 diopters difference between both eyes without glasses, could I still have a good vision by using multifocal progressive glasses?

[John C Hagan III, MD, FACS, FAAO]

Trying a a contact lens would still give you a feeling for monovision, especially if your cataract eye see's 20/50 or better. It's still worth a try.

If you aimed your left eye to 0.00 and you right is -3.00 aiming for monovision AND you didn't like it and you couldn't wear glasses or contact lens then you could have LASIK on the -3.00 eye to move them both to distance. You would need glasses for anything closer than 20 feet that is mid-range and reading.  LASIK does NOT work well taking a 0.00 eye and making it more nearsighted like -1.50 to -3.00.  You also would have the extra expense of paying for LASIK to change -3.00 to 0.00.

In my experience most patients are happier leaving the second eye a myopic but less than the first ie on the secsond eye shoot for -1.00 to -1.50.

JCH III MD  Ophthalmologist

[shamir]

You wrote: " You could ask your surgeon to put a -8.50 soft contact lens for several hours for you to see what it would be like with 0.0 in that eye after surgery.  Then he could put a -5.50 soft contact lens in the left eye to let you see what -3.00 would be like. We do this all the time in our practice for people contemplating monovision. "
My remark about that: my left eye has now cataract. I am afraid that if I put a -8.5 contact lens in my left eye I will not see well because of the cataract and it would be difficult for me to come to a conclusion about monovision.
Assuming that my surgeon corrects now my left eye to -3 with a IOL could I later get to monovision with laser corrections? What would be the risks?

[John C Hagan III, MD, FACS, FAAO]

The margin of error for normal sighted eyes is less then 1 diopter, in most cases .50 diopter or less. As eyes become very short or very long or if they have had RK the margin goes UP.

That's why eye surgeons generally try and leave eyes a little on the mypic side. If someone is left farsighted they need glasses for far, near and mid-range.

JCH III MD

[shamir]

Thank you for your answers.
I am no more interested in a monovision option as I understand all the potential problems.
Still considering the next surgery ( next week) on my left eye with a present -8.5 and my wish to bring it  to -3 with a monocular IOL in order to have equilibrated eyes ( my right eye is now after surgery at -3) could you tell me what is the expected accuracy of the procedure?
After the surgery I intend to wear progressive glasses to correct short sight and astigmatism.
My right eye is now at -3 one week after surgery. How much can this be changed in the next month?
This information would be very useful to me for my next talk with my surgeon (to morrow) and also to have a better understanding of the possible outcome of my two cataract surgeries.

[John C Hagan III, MD, FACS, FAAO]

This forum is never meant to replace a person to person discussion between patient and their ophthalmologist (Eye MD). These are generalizations:

1. What will make you "happy" in terms of targeted corrections is up to you. Discuss it with your surgeon to be sure its realistic.
2. Choosing a implant to leave a person at an exact number (like -2.00 or 0.00) is not an exact science and as the eyes get longer or shorter becomes less exact. However your surgeon can put in a "fudge factor" based on your outcome in the first eye.
3. Unless its an emergency you never have to rush into surgery.
4. You could ask your surgeon to put a -8.50 soft contact lens for several hours for you to see what it would be like with 0.0 in that eye after surgery.  Then he could put a -5.50 soft contact lens in the left eye to let you see what -3.00 would be like. We do this all the time in our practice for people contemplating monovision.

Good luck.
JCH III MD Eye Physician and Surgeon

[shamir]

Thank you for your advice. If I do not choose the monovision option what would be the best choice for a monofocal IOL for my left eye during the second cataract surgery?
At the first surgery the goal was -2 diopters for the right eye and I got -3 diopters. The surgeon explained the 1 diopter difference by saying "that it is not mathematics". My preferred choice now would be a result of -3 for the left eye. Both eyes would work together and I would not need some more surgery for corrections. I am not at all interested in going through further surgery after my second cataract operation. I understand that if the left eye (now at -8.5) was corrected at -2 or -1.5 there might be some advantages (like computer work without glasses) but I am afraid of complications like getting a larger difference between eyes than predicted.
If the goal is -3 diopters for the left eye should the surgeon aim at -2 diopters as it was for the first operation? How much is the uncertainty on the outcome of the second operation?  Is the uncertainty on the outcome of the second operation reduced after the first operation? My last question is: is it reasonable to do the second surgery 2 weeks after the first one as the near sight of my right eye could still change during the next weeks? Should I wait longer? How much can the near sight change?
One reason why I thought to monovision is that I manage very well with the present situation having -8 at the eye and -3 at the right eye and using glasses. But it seems that I see mainly the image of the right eye which is much better than the image of the left eye which is still with cataract. Therefore when the left eye will be without cataract I do not know how I would manage if the two eyes were -3 diopters apart.
I shall continue with glasses as it was for the last 60 years.

[John C Hagan III, MD, FACS, FAAO]

Your surgeon has an excellent point and is relying on experience and problems some people have with a 3 diopter difference between the eyes (in your case right eye -3.00 and left eye 0.00).   First if you have never tried monovision before with contact lens you might not like it. You don't see as good because you are using only one eye for distance and one for near. Your depth perception won't be as good. You will have midrange problems (computers, shopping, speedometer, name tags at parties, etc).

Additionally many people cannot adjust to glasses with more than 1.5 diopter difference in the two lens. Thus a prescription of RE -3.00 Left eye 0.00 may be uncomfortable to you or you may not be able to wear them at all.  It this happens you're in a fix. You might need lasik on the -3.00 eye to make it 0.00 or -1.50.  An implant exchange is sometimes more of an operation than the original cataract surgery.

Think hard about taking your surgeon's recommendations.

JCH III MD  Eye Physician and Surgeon