1. Biometry before catarct surgery
Ulrich Spandau
Department of Ophthalmology, University of Uppsala, Sweden

2. I will talk about: A-scan biometry – IOL Master biometry
Examination of a patient
IOL talk with the patienten
Clinical examples
Tipps & tricks

3. How good is today the quality of the calculation of an IOL ?
Question: How many patients with target refraction emmetropia become hyperopic?
Svar: 40%
Question : How many patients land at ± 0,5D?
Svar: Only 72%
Question : How many patients land at ≥ 10D
Svar: 40 patients
Europeiska katarakt register (n= patienter i 2014)

4. IOL-Master (laser, similar to TV)
Difficult measurement for ultrasound
Easy measurement för IOL master
IOL-Master (laser, similar to TV)
A-scan (ultrasound,
(similar to radio)
Ultraljud mäter med ljud, IOL master mäter med ljus
Difficult measurement for IOL master
Easy measurement for ultrasound

5. Ultrasound: A-scan
Measures from cornea
to ILM
ILM

6. IOL Master
Measures from cornea
to RPE
RPE 6

7. Important
Biometry with PMMA IOL: Big mistake with ultrasound; small mistake with laser (IOL Master)
Biometry with silicone oil filled eye: Big mistake with ultrasound (eye becomes 30% longer); small mistake with laser (IOL Master)
Caution: In case of mature cataract=> ultrasound; in case of PMMA-IOL and silicone oil =>IOL Master
Allt som är vattenfylld (biologisk, t.e.x matur katarakt) ultraljud; vid IOL, vid silikonolja IOL Master 7

8. IOL Master biometry Oculus Dexter Oculus Vänster IOL formula
Three important
parameters for formula
AL=Axial length
K=Keratometry
Oculus Dexter
Eye status
Different lins types
Oculus Vänster
OD=Oculus dexter och OS=Oculus vänster; Vänster alla paramter av formeln AL, k1, k2

9. IOL formula
Haigis
Hoffer
Holladay
SRK

10. SRK Donald R. Sanders, PhD, MD; John A. Retzlaff, MD;
Manus C. Kraff, MD
SRK/T (Teoretisk)

11. SRK I functions well for 22.0 – 24.5
SRK II was developed for long and short eyes:
< 20.0mm => add +3 to A constant
20.00 – => add +2 to A constant
21.00 – => add +1 to A constant
22.00 – 24.5 old SRK I formel
> 24.5mm => add -0,5 to A konstant
Problem: 20.99mm => add +3 BUT mm => add +2
=> Development of SRK/T

12. IOL formula P= A – 2,5 x L – 0,9 x (K1+K2)/2
P= IOL power in emmetropia
A= IOL constant
L= axial length in mm
K= corneal curvature i diopters

13. IOL formula contains
1) Keratometry
2) Axial length
3) A-constant

14. A-scan biometry Formula Tre essential parameter Different lins types
Lins typ A

15. Examination of patient
Examine ALLWAYS BOTH EYES
1) Autorefractor
2) Glasses
3) Biometry
4) Function of eye
Viktigast är autorefraktor och biometri

16. Biometry: Status of eyes
Pseudophakic
Phakic

17. Measurement of axial length with IOL master

18. Choose correct eye status

19. Empty space=> do a manual entry

20. Target refraction

21. Target refraction Cataract surgery first eye ? OR
Cataract surgery second eye?

22. Cataract surgery first eye
Free choice for
target refraction

23. Cataract surgery second eye
Do an objective refracation of the first eye
Target refraction of the second eye shall correlate with refraction of the first eye
Example: Pseudophakic eye: -2,0D, phakic eye: +1,0D, which vilken target refraction?
(-2,0D)

24. Target refraction => Talk with patient
Required measurements:
Refraction of eyes
Refraction of glasses
and biometry

25. Example 1
Patient is sailor and wishes to read his instruments in a disctance of 1,2m:
Target refraction?
Formula: 1/X => 1/1,2m=0,8D

26. Example 2: Hyperopia Refraction: +8,0D
Patient wears his glasses the whole time
Plan light hyperopia: +0,25-0,5D
He/she will no become myopic

27. Example 3: Grav myopia Refraction: -8,0D
Patient wears glasses constantly
Plan myopia: -1,0D
Patient does not want to be hyperopic

28. Example 4: Reading myopia
Refraction: -3,0D
Patient reads without glasses
Target refraction: -3,0D

29. Caution: Hyperopic shift
According to the cataract register many eyes become hyperopic after cataract surgery (cirka +0,5D)
=> In case of emmetropia plan for -0,5D

30. My favourite target refraction
Dominant eye: Emmetropia
Not-dominant eye: Light myopia (-0,75sph)

31. Wrong postoperative target refraction : Where is the mistake?
Everything between +/- 1,5D is acceptable
Double-check:
Did I implant correct IOL?
Was the biometry correct?
=> repeat biometry postoperatively (pseudophakic acryl)
Do OCT to exclude a membrane
5 det borde vara rätt

32. Postoperative anisometropia: Surgical action
1) IOL change 2) Implantation of an add-ON IOL

33. Lins change

34. Video: Lens change

35. add-ON IOL
Photocourtesy 1stQ, Tyskland

36. Tipps and tricks

37. Caution in case of white cataract !!
Swinging flash-light test:
RAPD pos => no surgery
RAPD neg => surgery

38. Tipps in case of mature cataract
Difficult to measure axial length with A- scan:
Change settings to ”aphakic”
BUT: AXL becomes too short
Add 0,3mm to AXL

39. Caution in case of LASIK!!
In case of LASIK surgery
=> Use formula Haigis-L

40. Caution!! Hard contact lenses
=> no contact lens use for 1 month, otherwise wrong biometry

41. Conclusion A-scan: measures from epithelium to ILM
IOL Master: measures from epithelium to RPE
Biometry: Are there strange values (for example IOL of 50D, AXL of 17mm)?
Dialogue with patient regarding lins choice (In case of reading myopia => target refraction: -3,0D)
3 är näthinnan avlossad?

42. Thank you for your attention