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Definition of 'Power' in monofocal IOL's ?

# 1
       when 'measured'  pre-operatively for monofocal IOL for two eyes (to be done 2 weeks apart) is it 'usual' to have the measurements taken for both eyes at the same visit ?  Or is the 2nd eye's measurment determined by the outcome of the first eye's surgery results?
                When i see the word ''power' on the identification card for each eye, the numbers are different i.e. 15.5D and 16.5D .   I thought that 'power' in this case refers to a 'correct' power of vision (same idea as when one gets refracted for eyeglasses)  OR do the 'monofocals' (for distance only) come in 'one size fits all' insofar as 'distance' vision is concerned? Should both eyes have the same 'power' number?    as you can tell i'm 'confused' .
          Thank you so much in advance - Edythe
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233488 tn?1310693103
MEDICAL PROFESSIONAL
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Avatar universal
Hello  ... - seems i have 'more' questions 'after' then 'before' the surgery! - LOL  but now i understand enough to realize i know 'nothing' !!  
            .. Since i opted for the standard IOL and had nothing done about the astigmatis then i understand that  i will definitely then need the astigmatism/intermediate/near glasses that will be prescribed in about 5 weeks and  as of yesterday's post-op check up both eyes are now seeing 20/20!!   (after all the visits tho i'm wondering if i memorized the eye chart?! - only kidding)  but i'm thrilled with the results and after a lifetime of being severely nearsighted (think Mr. Magoo)  it's nice to know i can 'socially' exist without glasses for distance.  
          Thank you again for your kind assistance and for patiently answering my questions - Most respectfully - Edythe
Helpful - 0
233488 tn?1310693103
MEDICAL PROFESSIONAL
1. Picking IOL powers is NOT an exact science and there is an error factor of =/-  0.50 diopters (larger in very long or very short eyes).
2. A spherical IOL will not correct astigmatism. That would need to be done with placement of the incision, toric IOLs, limbal relaxing incisions or glasses or contact lens after the surgery.
3. You will not hurt you eye by not wearing glasses and you can go without them any time you want.

4. May people with perfect "plano" (window glass) RX after surgery for distances of greater than 20 feet wear no-line progressives, or trifocals or bifocials after surgery to see at intermediate and near.

JCH MD
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Avatar universal
if i understand what you said when i get tested for glasses i will have 'no' correction for distance since my IOL's are distance only - Alcon Acrysoft IQ SN60WF  (13. Omm) & 6.Omm, both eyes -15 5.D & 16.5.D  but can receive correction for tri-focals (intermediate distance & close-up)...
           I also have an astigmatism - is correction for that condition ''added' to the distance vision also requiring that i wear glasses all the time for distance?  i would enjoy not wearing glasses for social occasions - walking into a room and actually faces !!
           Lastly,  even if the distance correction in glasses includes correction for the astigmatism, could i remove my glasses when desired for distance and still 'function' ?   been so nearsighted all my life the 'novelity'  of occasionally not wearing glasses for distance would be wonderful ... thank you again for your help = Edythe
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233488 tn?1310693103
MEDICAL PROFESSIONAL
Your tests will generate a set of theoretical IOP powers that will leave you with residual refractive errors of "zero" (that would give good distance vision)  -1.00 (Good intermediate vision) or -2.00 (good reading vision). The ophthalmologist and patient then set the goals of uncorrected vision.

JCH MD
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2 Comments
Now I am confused. My optometrist told me 2.00D for reading (left eye), 0.5D (Right eye) for distance. He knows I will use a form of sunglasses outside always, corrected to give 20/20 to both eyes.  What focusing range can I expect for each eye.
That can't be answered as it depends on your age and the amount of residual focusing power your ciliary body/lens still has and variables such as the size and mobility of your pupil.
Avatar universal
Hello - i hope i didn't confuse the issue with my question regarding the two different D-readings ... i didn't know about the 'lower power' contributing to better distance, etc.   I just wanted to explain that i thought i was fitted for 'distance  only'  for the  IOL's in both eyes    - i will be getting a prescription later for 'reading/computer'  etc... but do i understand even ''without' the reading-glasses there is still some 'reading' vision in the 'monvision' -distance IOL's ?  if afirmative, will that 'difference' cause any problems distinguishing 'distance' since each eye 'D' number is different?  And is the  'difference'   between the two eyes in the D-readings done for 'that' purpose or was it just 'my' readings happening to end up like that?  Reason i ask is i heard that one can have a 'distance' IOL in one eye with a 'close' IOL in the other - i would not have elected for that ...  Many thanks again ...Edythe
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233488 tn?1310693103
MEDICAL PROFESSIONAL
Generally the eye with the lower IOL power will have better distance vision and the larger number better reading vision WITHOUT glasses.

JCH MD
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Avatar universal
Thank you so very very much for answering my questions !!!  
First eye done june 11th...2nd june 25th.   Seeing distance clearly - amazing since i was very very nearsighed all my life. i am 71    :(
    one thing concerning me is that the  2-week old eye with the lower diopter (15.5)  done on june 11th is not seeing as 'sharply' for print material ( i.e. letters on t.v. screen closed-caption, etc) as is the most recently corrected eye (5 days ago).with 16.5D ....will this variance affect my distance when i try to focus on driving , read traffic signs, etc.
       don't know if this is relevant but in both eyes  i'm close to 20/25 post-op, plus the most recent eye with the 16.5 still has a very small pupil .... the surgeon stated it  will eventually match the 15.5D eye ((if its 'size'  has any 'cause/ 'affect' on what i described above)
        I still have to receive a prescription for my close-vision and i did have an astigmatism prior to surgery and i don't think that was corrected... i wanted to go with the 'simple' approach which would require glasses after surgery and i was wearing trifocals for at least the last 30 years.
        Thank you so much again for helping - it is greatly appreciated-Most Respectfully - Edythe
Helpful - 0
233488 tn?1310693103
MEDICAL PROFESSIONAL
1. BOth eyes are normally tested at the same time.
2. D in the IOl power is "diopter" a unit of bending power of light.
3. One size doe NOT fit all as far as power. One diameter fits all but the power will vary from person to person and eye to eye.

JCH MD
Helpful - 0
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