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iol calculation
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iol calculation

hi i have recently had iol lense exchange but my right eye is not what i was expecting so in laymans turms could you explain to me how the optometrist calculates the lense power needed
                                    kind regards wayne
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Avatar_f_tn
Measurements of the length of your eye and the curvature of your cornea are plugged into a complex formula.  This usually provides a pretty close estimate of the correct IOL power for you.  BTW, cataract surgeons are ophthalmologists with M.D.s.  Optometrists generally limit their practice to prescribing glasses and contacts.
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thanks for the reply jodie the reason i am curious about the calculations and formulas is i have had a tetraflex implant in both eyes and i was prescribed and fitted a 34 in my left eye and a 32 in my right eye (my left being the worst) i would like to know why fit a different power lens in each eye as i have been wearing contact lenses for years and for the last 5 years the prescription has been the same in both eyes so its making me wonder if i would benafit from a 34 in both eyes ?
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Avatar_f_tn
Your IOL power is not always consistent with your prescription.  I used a  different power lens in each eye, although my pre-surgery prescription was the same in both.  The formulas used for the calculations don't always work perfectly.  You might want to discuss your particular situation with your doctor if you're not satisfied with your outcome.  Possibly a LASIK touch-up would improve your vision.  
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If you had a 32 or 34 power implant - then you must have been very, very farsighted - perhpaps a +7 or +8.  Because  your measurements are so far off the norm (much more than 2 standard deviations) there is a much greater chance of having a refractive surprise.  Now if you just had an IOL exchange, the chances should be a litte better because you arlready know exactly how far off you are from the first surgery - so the second surgery should be just a refinement of 1 or 2 or 3 diopters.  It is common for eyes to be a little different and actually, your eyes are rather closes.  If you could keep refractive error within 1 or 2 diopters of plano that would be an excellent result considering your startig point.  Probably not a great tetraflex candidate because that choice in itself is giving you the idea that you will see well without glasses and because your calculations are so difficult - there is a fairly high chance that you WILL might glasses anyway - so why go with an accommodating type implant anyway?  It's hard enough to make you happy even with a monofocal implant -much less take on the possible new challanges of an accommodating implant.

MJK MD
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in all respect MJK that explanation was way above my head you obviously know what your talking about but all i am is a rolls royce engineer and knot a MD, my original prescription of contact lens was +5 in both eyes thats why i cant understand why they have put a 34 in my left and a 32 in my right eye in layman's terms what questions do i need to be asking and how will i know if they are bull shitting my
                                       very kind regards wayne
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Avatar_f_tn
Calculating IOL power is not an exact science.  I think that Dr. Kutryb was suggesting that the available formulas don't work as well for people (like you and me) who are severely nearsighted/farsighted/astigmatic.  (I had three excellent surgeons tell me that I'd probably need glasses/contacts for most activities post-surgery.)

Dr. Kutryb also suggested that based on the results of the surgery on your first eye, the calculations for your second eye might be modified slightly to get closer to your target.  Perhaps this is why the  IOL powers in each of your eyes is different.  (Do you have better vision from the eye that was done second?)  It's also true that your IOL power is not necessarily consistent with your contact lens prescription.  For example, lenticular astigmatism would effect your contact lens prescription but not the power of your IOL.

With a premium lens like the Tetraflex, it natural to expect to see well without glasses.  (After all, you paid good money for the "premium" lens.)  The question I'd be asking in your place is whether a laser vision touch-up would improve my vision.  In the US, some surgeons include the cost of a "touch-up" procedure in the premium lens. surcharge.    
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hi again jodiej thanks for your response my optometrist has already said that they will preform corrective laser surgery to finish my treatment within the price but i just wondered what the outcome would of been if they put a 34 in both eyes
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Avatar_f_tn
They say hindsight is 20/20--maybe a 34 in both eyes would have been better.  But as Dr. Kutryb stated, the formulas they use to calculate IOL power are less reliable with significant deviations from plano.  Let us know how you like the Tetraflex after your touch-up.  It's not available yet in the US, but I've seen promising reports about its success.
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i have my next check up next Wednesday so very soon after then i should have my correction laser treatment and yes i will let you know how it goes thanks jodie for your interest
                     very cool regards wayne
      
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hi jodie i know its been a long time coming but i had my correction laser surgery three weeks ago its got rid of the double vision but im now left with everything being blurred so now i think i am having to have another top up surgery but i dont know what sort laser or a new implant ?????? ill let you know xxxxx
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Avatar_f_tn
What a lot of problems!!  Hope they get it right soon.
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ye me too
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hay jodiej its me again i just thought id let you know after all the hastle iv had i asked the optometrist to diolate my pupil so he could see all the implant and guess what, yes you got itit was not inserted right so iv had to go 8 months with blurred vision they said i had a stigmatime so they lasered me and now they have found the implant has not unfolded all the way out so now iv got to under go surgery again to habe that removed and a new one fitted what you you think to that load of **** i am totally with ultralases surgens
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Avatar_f_tn
Amazing that it took so long to find the cause of your blurred vision!  At least you can look forward to improved vision once it's corrected.
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yes i suppose so but if i hadn't told them to do the test it would of never been found which is a bitter pil to swallow
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yes i suppose so but if i hadn't told them to do the test it would of never been found which is a bitter pil to swallow
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Avatar_m_tn
Hi

I had tetraflex iol exchange 3/4 weeks ago.

Right eye spot on calculation sph from -7.00 down to -0.25 great vision.

Left eye                                sph from -5.5 down to -1.5  blurred visionat all distances.

The left eye is astigmatic 3.0 a.
The company in charge is Optimax and they will make final corrections with laser surgery in a few months.


Tommy47.

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Avatar_f_tn
How is your near/intermediate vision in your right eye with the Tetraflex?
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Avatar_m_tn
Hi

My right eye is 20/20

Great far  and intermediate vision.
Reading excellent for  Computer, TV text and books. Newspaper print just about.
This should improve with practice.

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Avatar_m_tn
Hi

My right eye is 20/20

Great far  and intermediate vision.
Reading excellent for  Computer, TV text and books. Newspaper print just about.
This should improve with practice.

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Avatar_f_tn
Sounds good.  Please update us about your progress.  The Tetraflex may be available in the USA soon, and I'm sure that many people here will be interested in learning about your results.
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