P R K in 2005Bernard Mathys, MDBrussels

Brief history15 Y of follow-upExcimer laserRelatively easy techniqueShort learning curve

LimitsPainRegressionHaze ( > -6D)

PRK fights backComplications of LasikEpithelial ingrowth Striae, foldsSOSEctasiaFlap induced HOAProblem flap size/wide OZ for hyperopia

PRK improvedImproved lasers: scanning, flying spot, GaussianImproved OZ, transition Z, blend ZImproved nomogramImproved tracker: centration, cyclotorsion, frequency, mechanical response ? Aspheric profile: better for HOA ?

AdvantagesLimits induced HOALower rate of irregular astigmatismWave-front guided: Fourier > Zernicke ?Customized treatment

Results

No higher RMS postop for high correctionNo higher RMS postop for large OZSeems to reduce RMS for OZ 6 6.5Safe and effective: no loss of VA

RMS changes

And soPRK, Lasek > Lasik ?Flap induced HOA: nomogram correctionFDA studies for Lasik. PRK ?In fact, photoablation creates HOA !!No real studies in litterature

PRK Follow-upPainFluctuationsHaze

PRK best treatmentCorneal cooling Quick removal of the epitheliumCLAINS (ketorolac) 3dTearsSterods ?

AINS (ketorolac)

PRK haze ?Activated keratocytes collagen I-IIIMore frequent if: delayed epithelial responsedeep ablation, > -9Dbroad beam, more energy, retreatment Gabbato,Ophtal. online, dec 2004Max 3 to 6 MDecreases with time: metalloprotease Kato After 1 Y: scarMMC 0.02% 2 min

Best healing response ?Amniotic membrane ?Interferon ?Growth factor ?PA ?

SoPRK indications ?Up to -5 DK < 39 and > 48KT subclinicalThin corneaDry eyesHigh astigmatismArmy, pilots, athlete

Even more indicationsHyperopesRefraction error after IOLRefraction error after RKRefraction error after corneal graft

PRK after RK

And PTK ?

Irregular astigmatismRecurrent erosionReshapingHerpes (under treatment)

Then:Do not be ashamed to perform PRKMany indicationsHaze problems tend to diminishLasek = disguised PRKNot a single ectasia after PRKGood PRK much better than a bad Lasik !!

Good PRK >< Bad Lasik

Thin corneas

Follow-up 1 Y

Limited induced aberrations

High astigmatism

Same patient, topography

Thank you for your attention