p r k in 2005
DESCRIPTION
P R K in 2005. Bernard Mathys, MD Brussels. Brief history. 15 Y of follow-up Excimer laser Relatively easy technique Short learning curve. Limits. Pain Regression Haze ( > -6D). PRK fights back. Complications of Lasik Epithelial ingrowth Striae, folds SOS Ectasia - PowerPoint PPT PresentationTRANSCRIPT
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29/01/05 www.drmathys.beBSCRS 2005
P R K in 2005
Bernard Mathys, MDBrussels
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Brief history
• 15 Y of follow-up
• Excimer laser
• Relatively easy technique
• Short learning curve
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Limits
• Pain• Regression• Haze ( > -6D)
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PRK fights back
• Complications of Lasik– Epithelial ingrowth
– Striae, folds
– SOS
– Ectasia
– Flap induced HOA
– Problem flap size/wide OZ for hyperopia
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PRK improved
• Improved lasers: scanning, flying spot, Gaussian
• Improved OZ, transition Z, blend Z
• Improved nomogram
• Improved tracker: centration, cyclotorsion, frequency, mechanical response ?
• Aspheric profile: better for HOA ?
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Advantages
• Limits induced HOA
• Lower rate of irregular astigmatism
• Wave-front guided: Fourier > Zernicke ?
• Customized treatment
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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
Z-preopZ-postopS-preopS-postop
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• 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
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RMS changes
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29/01/05 www.drmathys.beBSCRS 2005
And so…PRK, Lasek > Lasik ?
• Flap induced HOA: nomogram correction
• FDA studies for Lasik. PRK ?
• In fact, photoablation creates HOA !!
• No « real » studies in litterature
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PRK Follow-up
• Pain
• Fluctuations
• Haze
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PRK best treatment
• Corneal cooling
• Quick removal of the epithelium
• CL
• AINS (ketorolac) 3d
• Tears
• Steroïds ?
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AINS (ketorolac)
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PRK haze ?
• Activated keratocytes – collagen I-III• More frequent if:
• delayed epithelial response• deep ablation, > -9D• broad beam, more energy, retreatment Gabbato,Ophtal. online, dec
2004
• Max 3 to 6 M• Decreases with time: metalloprotease Kato • After 1 Y: scar• MMC 0.02% 2 min
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Best healing response ?
• Amniotic membrane ?
• Interferon ?
• Growth factor ?
• PA ?
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So…PRK indications ?
• Up to -5 D
• K < 39 and > 48
• KT subclinical
• Thin cornea
• Dry eyes
• High astigmatism
• Army, pilots, athlete
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Even more indications…
• Hyperopes• Refraction error after IOL• Refraction error after RK• Refraction error after corneal graft
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PRK after RK
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And PTK ?
• Irregular astigmatism
• Recurrent erosion
• Reshaping
• Herpes (under treatment)
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Then:
• Do not be ashamed to perform PRK
• Many indications
• Haze problems tend to diminish
• Lasek = disguised PRK
• Not a single ectasia after PRK
• Good PRK much better than a bad Lasik !!
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Good PRK >< Bad Lasik
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Thin corneas
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Follow-up 1 Y
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Limited induced aberrations
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High astigmatism
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Same patient, topography
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Thank you for your attention