1. Phacoemulsification some Basic Ideas…
Khalid M. Al-Arfaj, MD
Dammam University

2. 1-Quiz …
2- lecture …
3-Vedio …

3. Basic Phaco Settings

4. Basic Phaco Settings
Sculpting
60 / 80 / 24
US, Vac, Asp.

5. Quadrant Removal/Burst
45 / 400 / 37 BW

6. Quadrant Removal/Pulse
45 / 376 / PR 6

7. Horizontal Choping

8. Vertical Choping
Courtesy of David Chang, MD

9. Evolution of IOL Calculation Formulas
Clinical History Formula
Used before 1975
Simple formula to calculate IOL power
P = 18 + (1.25 x Ref)
Poor accuracy
>50% had >1D error
“9 D surprise” – some huge errors due to the inaccuracy of calculating refractive error prior to cataract formation

10. Formulas and Their Derivations
Regression Formulas
Derived from retrospective computer analysis of postoperative data from a large number of patients
SRK Formula
P = A – 2.5L – 0.9K
Derived by Sanders, Retzlaff and Kraff1
Required measurements
L – Axial length (mm)
K – Corneal power (D)
A – A Constant
1 Sanders DR, Retzlaff J, Kraff MC. Arch Ophthalmol 1983;101:

11. Formulas and Their Derivations
SRK and early Theoretical formulas fairly accurate for eyes of moderate length
Inaccuracies occurred at extremes of axial length

12. Modern Theoretical Formulas
Most important concept is postop Anterior Chamber Depth is related to IOL placement in the eye, not to preop ACD
All have a personalizable factor to improve accuracy of calculations
Holladay/Holladay 2
S factor – personalized surgeon factor
SRK/T
A constant – based on multiple variables (IOL manufacturer, implant style, surgeon’s technique, etc.)
Hoffer Q
Personalized ACD value

13. Modern Theoretical Formulas
All based on Thin Lens Optics

14. Modern Theoretical Formulas
Found to be more accurate than older formulas
All basically the same in predicting IOL power in average eyes
Differences occur at extremes of AL and K’s
Personalized factors based on optimal cases (PCIOL, intact capsule)
Must change when surgical plan changes (Sulcus PCIOL or ACIOL)

15. Axial Length Measurement
Current methods
Contact A Scan Biometry
Optical Biometry
Partial Coherence Interferometry

16. A Scan Biometry Use of A scan ultrasound to measure axial length
Contact

17. Normal Phakic Contact A Scan
C1 – Anterior surface of Cornea
C2 – Posterior surface of Cornea
L1 – Anterior surface of Lens
L2 – Posterior surface of Lens
R – Retina

18. Optical Coherence Biometer
IOL Master
Fine beam of infrared laser used to measure axial length

19. ultrasound vs. optical biometry
Ultrasound A-Scan
10MHz sound wave
IOLMaster
780nm laser beam
ILM
RPE
averaging across foveal cup
reflection at Bruch's membrane
Foveal thickness is about 150µ (±20) from ages 10 to 80 years.
The parafoveal area is between 0.10 mm and 0.16 mm thicker.

20. alignment precision: ultrasound vs. optical
Ultrasound A-Scan
10MHz sound wave
A-scan US does not measure to the exact center of the fovea, but samples an area around it due to the broad angle of the U/S beam and fixation light. ?
fixation blob
IOLMaster
780nm laser beam
IOLMaster uses a point fixation light, measures along visual axis to the RPE at foveal center and then adds back the foveal thickness.
fixation point

21. Comparison of three methods
myopia
hyperopia
partial coherence interferometry non-contact laser device phakic, pseudophakic, phakic IOLs posterior staphyloma, silicone oil not limited by wavelength or retinal thickness variations
myopia
hyperopia
applanation A-scan
falsely short axial length
variable corneal compression
corneal micro-abrasions
highly operator dependent
source of IOL power errors
90%
80%
70%
60%
50%
40%
30%
20%
10%
90%
80%
70%
60%
50%
40%
30%
20%
10%
spherical equivalent prediction error (D)
Data courtesy of Warren E. Hill, MD, FACS

22. Pearls and Pitfalls Measure axial length of both eyes
Take multiple readings of each to assure accuracy
Compare eyes
Shouldn’t be a significant disparity in axial lengths unless a significant difference in refraction
Axial Length
measure too short - myopic surprise
measure too long - hyperopic surprise
Normal Eye: 1.0 mm error  2.5 to 3.0 D surprise
Short Eye: 1.0 mm error  7.5 D surprise
Keratometry
1D curvature error  1D surprise

23. What is your target postop refraction?
IOL Power Selection
What is your target postop refraction?
Examine patient data
Discuss with patient
Match other eye?
Monovision?
Binocular distance?
Binocular near?

24. How do you choose IOL? Material Configuration Delivery system Silicone
IOL Choices
How do you choose IOL?
Material
Silicone
Acrylic
PMMA
Configuration
One piece
Three piece
Delivery system
Fold vs. Inject

25. Basic IOL Design Features
Haptic
Edge
Optic

26. Basic IOL Design Features
Haptic
1-piece
3-piece
diameter
Edge
Optic

27. Haptic Design 1
13.0

28. Basic IOL Design Features
Haptic
Edge
square
rounded
Optic

29. Square Rounded anterior reduced PCO reduced PCO dysphotopsias?
Edge Design
Square
reduced PCO
dysphotopsias?
Rounded anterior
reduced PCO
reduced internal reflections

30. Optic Design Material Focality/Sphericity Diameter Rigid Foldable
PMMA
Foldable
acrylic
silicone
collamer
Focality/Sphericity
Monofocal
spheric
toric
wavefront
aspheric
Multifocal
accomodative
pseudoaccomodative
Diameter
5.0 to 7.0 mm
6.0

31. Consider matching IOL design features with individual patient needs
Which lens?
Consider matching IOL design features with individual patient needs

32. High myopia Considerations: IOL size, power
Lens choice
High myopia
Considerations: IOL size, power
longer haptic span, larger optic diameter
low power

33. High hyperopia Considerations: IOL size, power
Lens choice
High hyperopia
Considerations: IOL size, power
smaller haptic span, smaller optic diameter
high power IOL

34. Presbyopia Considerations: spectacle independence
Lens choice
Presbyopia
Considerations: spectacle independence
multifocal IOL (accomodative, pseudoaccomodative)
monovision using two monofocal IOLs

35. Astigmatism (corneal)
Lens choice
Astigmatism (corneal)
Considerations: correct corneal astigmatism
Toric IOL

36. Improved functional vision
Lens choice
Improved functional vision
Considerations: maximize contrast sensitivity
aspheric

37. Macular degeneration Considerations: block toxic UV light
Lens choice
Macular degeneration
Considerations: block toxic UV light
blue blocking chromophore

38. Pseudoexfoliation Considerations: Long term zonular stability
Lens choice
Pseudoexfoliation
Considerations: Long term zonular stability
avoid silicone material (capsular phimosis)

39. Crystalens
“ Accommodating” Lens –single optic

40. Crystalens

41. Crystalens

43. The good Less capsule issues
The Multifocals
ReZoom & ReSTOR
The good Less capsule issues
Known material
Good near vision
The Bad: Unwanted photopsia
Contrast sensitivity

45. ReZoom

46. AcrySof® ReSTOR® Apodized Diffractive IOL

47. Anatomy of the Apodized Diffractive IOL
Step heights decrease peripherally from 1.3 – 0.2 microns
Central 3.6 mm diffractive structure
A +4.0 add at lens plane equaling +3.2 at spectacle plane

48. Patient Selection Pre-operative Exclusion Criteria
Subjective Exclusion
Hypercritical patients
Patients with unrealistic expectations
Occupational night drivers
Medical Exclusion
>1.0 D of corneal astigmatism?
Pre-existing ocular pathology
Previous refractive patients

49. Patient Satisfaction
Crystalens, ReZoom, and ReSTOR all have clinical studies extolling the level of spectacle independence, excellent near, intermediate, and far vision of patients with these lenses.

50. Future Technology
The HumanOptics IOL ( 1CU) is a single optic accommodative lens continuing in clinical trials in Europe.
(Image courtesy of HumanOptics, Ophthal Clinics of N. Amer. March 2006.)

51. Future Technology
Accommodative intraocular lenses with two optics. Gross photographs showing the injection of the Synchrony lens (Visiogen).
Source: Liliana Werner, M.D., Ph.D. and Nick Mamalis,M.D.

52. Sarfarazi Lens
Reproduced from Ophthal Clinics of N. Amer. March 2006 courtesy of Bausch & Lomb
The Sarfarazi IOL, currently licensed by Bausch & Lomb, is comprised of a minus-powered optic positioned posteriorly to a positive-powered optic joined by compressible bridges.

53. Other Technology
Lens replacement with flexible polymers injected into the capsular bag.