Question:
When I go in for my cataract pre-surgery sessions in about 6 weeks, is it really
_practical_ to have a 20/20 iol put in. I wonder about asking them to aim for a
light myopic lens.
My wife recently had a similar cataract op and when they asked just prior to
surgery what sort of vision she wanted she (naturally enough) said, 'why perfect
of course'.
So now she realises that the intraocular lens they inserted has less
accommodation than a natural lens. Vision up to 4ft is blurry. Hence she
requires reading glasses for most daily tasks - working, cooking, reading,
sewing, etc etc.
It occurred to me that a mild myopic ioc might be more useful, with accurate
close vision up to say 10ft, because for those daily tasks one could operate
well without glasses, then for distance vision, driving, etc, pop on the specs.
Seems that this second option would require less occasion for wearing glasses.
Then as I age the focal length might extend further, mightn't it?.
If I'm right, and a mild myopic iol is quite useful if it would give acuity up
to 10-20ft, what diopter would do this?
Am I wildly off the mark here, or is it a reasonable theory?
Answer:
You are right on target here! I oftentimes ask for my patients to end up
with a -0.50 spherical final refractive error after cataract surgery. Being
mildly myopic is a good thing when you are older. As you say, less
dependence on readers while still maintaining reasonable distance vision.
You could even propose to have 1 eye set perfectly for distance (plano) and
the other set slightly for near (-1.00 would be good). This is called
monovision. It can be difficult to adjust to at first but works quite well
in most cases.
I think your biggest problem will be the amount of astigmatism you presently
have. You posted that you have a cylinder correction of -3.00 in one eye
and -3.25 in the other. If this astigmatism is due to the toric shape of
your cornea (rather than lens tilt which is also possible) then standard
cataract surgery will likely leave you with about the same amount of
astigmatism even after the surgery. Thus your distance AND near vision will
be blurred regardless. Sometimes you can request that the surgeon perform
limbal relaxing incisions on your cornea during the cataract operation in an
attempt to remove/minimize that astigmatism. I would talk to your surgeon
about doing that or it really won't matter whether you are set perfect for
distance or slightly nearsighted after the surgery-- the astigmatism will
still make everything blurry and require that you use glasses full-time.
Talk to your surgeon about trying to set the final end point of your
refraction after surgery. Talk to him about possible solutions to your
astigmatism. Be aware that you can't exactly pick a final refractive end
point after cataract surgery-- it's impossible to be precise. Cataract
surgery IS NOT refractive surgery.
