42 old male, underwent phaco + IOL three days ago.
Due to failure of AL data capture using IOLMaster, AL, ACD values was provided by contact A-ultrasound measurement. SRKT formula was used for IOL power calculation.
AL: 25.11 mm; ACD: 3.95 mm, LT: 4.54 mm
K values were provided by IOLMaster: Kf 43.6D, Ks 44.35D
finally, a Hoya PC-60R (+16.0 D with target refraction of -0.58D)was implanted.
However, the postoperative refractive error for this patient was:
+1.0DS/+1.75DCX25° with BCVA 20/20, UCVA was 12/20.
we considered that the main reason of refractive error for this patient was the deeper ACD. In this condition, Haigis may be a good choice for IOL power calculation.
Is there any research about the ACD contribution on IOL power calculation in different AL?
Moreover, is there any other reasons for this big refractive error?
Thank you for your attention!
Hi! Yes, you are absolutely right! The main reason of your error is the VERY deep preop ACD! SO, in this case I am using only 4 or 5 generation formulas, or personal VRF formula, that take into account anterior segment size of the eye! The Haigis or Holladay 2 is appropriate choice too!
BR, Oleksiy!
The next error that was occur is the - ultrasound axial length measurament!
This method is very inaccurate! The 0,2-0,5 mm error may occur even in very experienced doctor! The eye may be shorter than you measured!
Last error is that you mixed K reading form IOLMaster and US AL data! The IOLMAster K reading some differ from K reading form Keratorefracmometer! As usual K from IOLMaster more steeper, so you get weeker IOL power than needed! So this 3 error coincided and you get big final hyperopic error!
BR, Oleksiy!
Have a nice day!
Thank you so much for your reply.
Is there any published paper about preoperative ACD and postoperative ACD changing contributed to postoperative refractive error? For example, the linear regression between them.
Personal VRF formula?
You are welcome! Pity, but I don't know articles about this theme!
Yes, VRF formula will be described in the near future in the AJOO periodical issue!
BR, Oleksiy!
I recently observed the same problem. While using IOL Master my calculation was ok. Using A-ultrasound measurements I have hyperopic shift! So in my opinion measurements done by different machines are not the same.
And as pointed mixing measurements from different machines is not a good idea- unless proven otherwise after a trial.
ACD as I observe is the reason why our calculation does not meet the refraction in real life. I aspeccialy noticed that in hyperopic eyes with shallow AC which more frequently remain slightly hyperopic after cataract removal.
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