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How to Improve your Refractive Cataract Surgery Outcomes by Skilful Interpretation of Corneal Mapping
Arthur Cummings FRCSEd Wellington Eye Clinic, Dublin, Ireland
Course IC-16 ESCRS Copenhagen 10th September 2016
Consultant for Alcon / WaveLight/TearLab
AIMS of Course
• Help manage refractive expectations of cataract surgery patients
• Help with managing toric IOL’s
• Help with LRI’s, OCCI’s, effect of incision size and architecture
• Help with selecting multifocal IOL candidates
Why address astigmatism?
• Astigmatism is the KEY factor for success with multifocal IOL’s
• Correcting astigmatism provides better UCVA, BCVA for distance
and near
• Glasses that may be required are lighter, cheaper and easier to
wear / get used to
What is “Refractive Cataract?”
• The intended outcome is emmetropia
• The intended outcome has addressed astigmatism
• The intended outcome may have addressed presbyopia too depending
on patient wishes (multifocal IOL, monovision)
• The patient is free of glasses for at least distance vision (monofocal,
emmetropia) or completely free of glasses
Devices
• Placido disk (in relative detail)
• Scheimpflug (in relative detail)
• Cassini (Introduction)
Topolyzer (Keratograph)
• Placido disk
• Tear film reflections
• Central scotoma where camera is situated
• Auto-capture, very repeatable
Oculyzer (Pentacam)
• Scheimpflug camera
• Captures scatter so does not see tear film but
corneal surface
• No central scotoma
• Auto-capture, very repeatable
Diagnostic Applications
• Screening for IOL’s (toric, multifocal)
• Screening for corneal health
• Screening for AC parameters
Cassini Corneal Topographer
Multi-spectral LED technology from i-Optics
Given the faster acquisition time and insensitivity to radial aberrations, corneal astigmatism is measured more accurately
How does the iTrace work?
• Simultaneous corneal topography and whole eye
wavefront mapping
• Refraction
• Can separate corneal from intra-ocular optics
• Can therefore help manage post-op toric IOL’s
Summary
• Value of adding posterior corneal data is understood
• What about the geometry and geography of the
crystalline lens and the final position and orientation of
the IOL?
• Mirricon from ClearSight may have more answers?
Results
Lenstar radius achieves a Mean Prediction Error of -0.02±0.52 D Pentacam radius achieves a Mean Prediction Error of 0.22±0.68 D
“Perfect” eye, Mean Prediction Error ± Standard deviation Lenstar vs Pentacam
Results Scenario III: Average Eye, Acrylic vs. Silicone
Acrylic IOLs are considerably less affected by IOL design, whereas silicone IOLs exhibit a much higher dependency, with the poorest results obtained for convex-plano IOLs.
biconvex
plano-convex
convex-plano
Pre-Operative
• IOL calculations
• IOL type
• Incision type
• Incision shape: 3 step, 2-step, straight-in
Pre-Operative
• IOL calculations
• IOL type
• Incision type: Scleral, limbal, corneal
• Incision shape: 3 step, 2-step, straight-in
• Incision size: <2mm, 2.2mm, 2.5mm, 2.8mm, >2.8mm
Pre-Operative
• IOL calculations
• IOL type
• Incision type: Scleral, limbal, corneal
• Incision shape: 3 step, 2-step, straight-in
• Incision size: <2mm, 2.2mm, 2.5mm, 2.8mm, >2.8mm
• Incision location: Superior, Temporal, on axis
Incisions and OCCI’s on steepest axis My OCCI nomogram: • Astigmatism < 0.8D
– Single 2.75 mm incision – Make slightly shallower to allow
slippage • Astigmatism 0.8D < X < 1.2D
– OCCI 2.2mm • Astigmatism 1.2D < X < 1.5D
– OCCI 2.75mm • Astigmatism 1.5D < X < 2.0D
– OCCI 3.0mm
OCCI = Opposite Clear Corneal Incision
Toric IOL`s vs. OCCI’s over 3 Months
-1.8
-1.6
-1.4
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0
Preoperative Week 1 Month 1 Month 3
Toric IOL`s
Incisions
Data courtesy of Kjell Gunnar Gundersen MD, PhD (Norway)
42.1 44.2
42.5 43.3
Decreased corneal astigmatism by 1.3 D
Good placement of incision. Incision enlarged in width. Incision decreased in length.
Pre-Operative
• IOL calculations
• IOL type
• Incision type: Scleral, limbal, corneal
• Incision shape: 3 step, 2-step, straight-in
• Incision size: <2mm, 2.2mm, 2.5mm, 2.8mm, >2.8mm
• Incision location: Superior, Temporal, on axis
Shallow Anterior Chambers
• Mostly hyperopes
• Mostly shorter eyes
• 3 critical values
– AC volume < 100 mm3
– ACD < 2.1mm
– AC angle < 26 degrees
Post-Operative
• Detecting tight sutures
• Detecting wound gape
• Detecting irregular astigmatism
• Guiding suture removal with the Pentacam