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

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Aberrations

• Measurements of all aberrations preoperatively

• Same postop: 1M, 3M, 6M, 12M

• Time development view

• Normal band view

• Orbscan

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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