Professor Ioannis Pallikaris Professor Ioannis Pallikaris MD, PhDMD, PhD

Different mediums (Nd:YAG Crystals vs ArF Gas)

Less optics for the shaping of the pulse No use of toxic gasses Improved beam quality and shape Reduced thermal effect and collateral damage Hydration dependence on 193nm

Hydration dependence on 193nm

Corrosive, toxic and high cost gases

Big spot size Absorption

coefficient suggest 193nm affected more by BSS or NaCl 0.9%

Mirror 90%

Medium

Pumping

ArF

193 nm@400hzMirror 100%

Medium

Nd:YAG

1064 nm

213 nm@300Hz

Non-linear optics

All treatments performed by CustomVis Pulzar Z1 & Allegretto 400

Last follow-up to 12 months PRK Mean SEQ = - 4.50 ± 1.81D

[-6.50D to -1.50D Sph and up to –2.50D Cyl] 160 eyes in Excimer and 160 in Solid MMC solution was applied to PRK cases in

both systems according to given attempted correction

LASIK and PRK for treating Myopia and Myopic

Astigmatism. A retrospective study.

89% between + 1.00/-1.00 D at 12 months postop for Excimer

96% between +1.00/-1.00 D at 12 months postop for Solid

35%% of eyes gained more than 1 line in Solid 31% of eyes gained more than 1 line in Eximer

157 eyes

0% of eyes changed more than 0.50D between 3m and last postop

Solid

•Smooth ablation surface

•No edema or distortion of the adjacent corneal stroma

•Normal structure of the endothelial layer in both groups

S

E

S

E E

S

The Descemet’s membrane and the endothelium did not demonstrate any morphological difference with intact tissues

S

E

S

E

Solid

ExcimerS

E

No statistical significant difference found between two groups in any postoperative interval (p>0.05).

Study group, 30 eyes underwent myopic PRK with the CustomVis Pulzar Z1 laser system.

Control group, 30 eyes underwent myopic PRK with the a Allegretto Wavelight 400Hz Excimer system

Coma Y Decrease 0.04

Coma X Increase 0.05

Spherical aberration Increase 0.04

HO rms Increase 0.08

0

0.04

0.08

0.12

0.16

0.2

0.24

0.28

0.32

0.36

0.4

0.44

0.48

0.52 preop

1month

3 months

6 months

12 months

PRKN=40 eyes

Attempted SpEq: -6.45 ± 2.5 D

Pupil diameter 6mm

Alcon LADARVision4000 System Wavefront-guided Excimer Laser Ablation Using PRK Mean attSphEq : -4.21D Diopters

6months postop :Pupil diameter 6mm

RMS HO: decrease 0.29Spherical Aberration: decrease 0.06Third order RMS: increase 0.13

Daniel S. Durrie,, et al JRS 2008

WaveLight ALLEGRETTO Laser Wavefront Optimized Treatments in Surface AblationMean attSphEq : -3.64 ±1.92 Diopters

3months postop:Pupil diameter 6mm

RMS HO: increase 0.03Spherical Aberration: increase 0.01Third order RMS: increase 0.03

Aleksandar Stojanovic, et al JRS 2008

Predictability presented similar results between the two systems The excimer seems to give more

overcorrection effect due to the use of MMC compared to the Solid system

Both system are safe for correction with PRK and LASIK

Stability of refraction is the same for both systems with stability level being equal at 12 moths PostOp period

Histology has proved to have similar results to the samples of Excimer laser

There are no statistical significant changes in corneal endothelium monolayer in post PRK patients (up to one year) with solid state (213 nm) and excimer (193 nm) laser systems.

Similar changes to high order aberration were found between Solid and Excimer