21/09/04 www.drmathys.be ESCRS 2004 PARIS Wavefront- and Topography-guided PRK for Myopic Eyes Bernard Mathys, MD Brussels Vision Clinic
Mar 29, 2015
21/09/04 www.drmathys.beESCRS 2004 PARIS
Wavefront- and Topography-guided PRK for Myopic Eyes
Bernard Mathys, MDBrussels Vision Clinic
21/09/04 www.drmathys.beESCRS 2004 PARIS
Zyoptix (B&L) for PRK
• 100 000 Procedures for Z – Lasik
• Orbscan and Aberrometry-guided ablation
• Tissue saving, wide optical zone, reduce treatment-induced aberrations
• Adapted for PRK – using the same preop measurements
21/09/04 www.drmathys.beESCRS 2004 PARIS
Why Zyoptix ?
• Thin cornea: < 520 µ
• Large pupil
• Tissue saving
• Aberrations preop > 0.30µ RMS
• PSF
21/09/04 www.drmathys.beESCRS 2004 PARIS
Technique
• Topography and aberrometry by the same well-trained technician
• Alignment under the laser, head position: crucial
• PRK: std technique
• Postop treatment: std
21/09/04 www.drmathys.beESCRS 2004 PARIS
Results
4,6
0,051
2,08
0,251,4
108,9
10,51
0
2
4
6
8
10
12
D/VA
refraction Std UCVA BCVA
preoppostop
21/09/04 www.drmathys.beESCRS 2004 PARIS
Aberrations
• Measurements of all aberrations preoperatively
• Same postop: 1M, 3M, 6M, 12M
• Time development view
• Normal band view
• Orbscan
21/09/04 www.drmathys.beESCRS 2004 PARIS
Example 1: thin corneas
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Example 1: thin corneas
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Example 2: large pupil
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Example 2: large pupil
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Example 3: limited induced aberrations
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Contrast sensitivity
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RMS changes
Planoscan
Zyoptix
Patient Categorized By PreOp Higher Order RMS
Ch
an
ge
in H
igh
er
Ord
er
RM
S f
rom
Pre
Op
(A
vg.
1W
, 1
M,
3M
Vis
its)
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0-0.24um 0.25-0.49um 0.50-0.74um 0.75-0.99um
p=0.023
Greater RMS than Pre Op
Less RMS than Pre Op
n=7 n=30 n=8 n=1
n=5 n=31 n=7 n=2
6mm Pupil
21/09/04 www.drmathys.beESCRS 2004 PARIS
Discussion
• If thin cornea, PRK more suitable• However, higher correction may induce
more haze, delayed visual recovery, regression, etc…
• Our experience: exactly the same• But Z-PRK: less haze, better astigmatic
correction, wider optical zone, no contrast loss
21/09/04 www.drmathys.beESCRS 2004 PARIS
Conclusion
• Very interesting technique
• Need a correction factor for the aberrometer measurements (ours: 90%)
• Alignment crucial
• Cyclotorsion
• Corneal marking for astigmatism
21/09/04 www.drmathys.beESCRS 2004 PARIS
• No higher RMS postop for high correction
• No higher RMS postop for large OZ
• Seems to reduce RMS for OZ 6 – 6.5
• Safe and effective: no loss of VA
21/09/04 www.drmathys.beESCRS 2004 PARIS
Thank you for your attention