Transcript Comparative Evaluation of Photorefractive Keratectomy With

Comparative Evaluation of Photorefractive
Keratectomy With Use of Excimer Laser and
Solid-State Laser System
G. A. Kontadakis; G. A. Kounis; G. D. Kymionis; A. Stratos; I. G. Pallikaris
Institute of Vision and Optics, University of Crete, Heraklion Crete, Greece.
The authors have no financial interest in the subject matter of this poster.
introduction
• Solid state laser technology was introduced in refractive surgery as an
alternative to the excimer laser. The gain medium in these devices is
Nd:YAG crystals that generate beam of 1064nm. The radiation that is
produced by transmitting the 1064nm beam throw a setting of non linear
crystals has a wavelength of 213nm. It has been proved to be suitable for
corneal ablation and also to have similar ablation profile with the 193nm
pulsed radiation. The main benefit of the 213 nm wavelength beam is that
it less absorbed by salt solutions and therefore the ablation rate is
probably less dependent on corneal hydration during surgery.
Purpose:
•
To compare refractive results of photorefractive keratectomy (PRK) with
the Solid State laser and Excimer laser.
Methods
• This retrospective cohort study comprised 82 patients (147 eyes) who
received PRK with the excimer laser Allegretto 400 Wave Eye-Q (group 1),
and 73 (145 eyes) who received PRK with the solid state laser Pulzar Z1
(group 2).
• All patients had a complete ophthalmic examination preoperatively to
exclude ocular disease. All procedures were performed by the same
surgeon (I.G.P.) using an identical technique.
• Preoperative and postoperative assessments included: uncorrected
distance visual acuity (UDVA), corrected distance VA (CDVA), manifest and
cycloplegic refractions, slit lamp examination and corneal topography.
• Normality of distribution of continuous variables were assessed with the
Kolmogorov-Smirnov test. Variables with normal distribution were
compared with independent samples t-test. When distribution was not
normal Mann-Whitney test was used to asses the differences.
Methods(2)
Treatment
Category
Low Myopia
0 to -3D SEQ
Moderate
Myopia
-3 to -6D SEQ
High Myopia
-6D to -12D
SEQ
73
(145)
34.1±8.5
[56-21]
(42/31)
Customvis Pulzar Z1
Patients
(Eyes)
Mean Age
Age Range
Sex (F/M)
Eyes
Mean Age
Mean
mmc
Time(sec)
40
34.4±9.7
4.1±5.6
87
33.5±7.8
10.1±8.2
18
35.1±9.0
20.6±8.1
Wavelight Allegretto 400
• Patient demographics:
82
(147)
31.9±6.1
[50-21]
(52/30)
Eyes
Mean Age
Mean mmc
Time(sec)
41
31.9±4.8(p
=0.57)
6.3±4.3
87
31.8±5.9
12.8±5.6
19
33.7±8.8
23.8±6.5
SEQ: sherical equivalent; mean mmc time is the mean time of intraoperative
Mitomycin C application. All parameters did not show statistically significant
differences between the groups.
Postop results for Customvis Pulzar Z1
Results:
3 Months PostOp
Low Myopia > 3.0D
Moderate
Myopia
-6.0 < ≤ -3.0D
Rem SEQ†
0.02±0.52
-0.07±0.63
Mean Rem
Refraction†
0.16/-0.28@178°
LogMar CDVA‡
LogMar UDVA‡
12 Months PostOp
Low Myopia > 3.0D
Moderate
Myopia
-6.0 < ≤ -3.0D
High Myopia
≤ -6.0D
0.31±0.97
0.01±0.52
-0.11±0.65
0.24±0.77
0.10/0.35@174°
0.6/-0.58@2°
0.25/-0.48@13°
0.04/0.31@180°
0.46/0.43@15°
-0.05±0.05
-0.04±0.04
-0.01±0.09
-0.06±0.04
-0.05±0.06
-0.05±0.12
-0.02±0.1
0.01±0.08
0.08±0.14
-0.03±0.05
0±0.1
0.05±0.11
High Myopia
-6.0D
≤
Postop results for Wavelight Allegretto 400
3 Months PostOp
12 Months PostOp
Low Myopia > 3.0D
Moderate Myopia
-6.0 < ≤ -3.0D
High Myopia ≤ 6.0D
Low Myopia > 3.0D
Moderate
Myopia
-6.0 < ≤ -3.0D
High Myopia ≤ 6.0D
Rem SEQ†
0.12±0.46
0.37±0.61
0.87±0.65
-0.04±0.47
0.32±0.51
0.29±0.42
Mean Rem
Refraction†
0.17/-0.11@170°
0.44/-0.13@7°
0.99/-0.24@178°
-0.03/0.02@21°
0.42/0.21@175°
0.41/-0.25@43°
LogMar CDVA‡
-0.07±0.07
-0.05±0.07
0.03±0.11
-0.06±0.07
-0.07±0.07
-0.05±0.05
LogMar UDVA‡
-0.05±0.08
-0.03±0.08
0.04±0.13
-0.01±0.12
-0.03±0.11
-0.02±0.09
Rem SEQ: (attempted correction)-(achieved correction) in spherical equivalent
Differences between parameters in corresponding laser groups were not statistically
significant
Solid state laser
Results:
safety
Excimer laser
Both laser
platforms
performed
similarly in terms
of safety of the
procedure
Solid state laser
Excimer laser
Results:
predictability
Procedures performed
with both laser
platforms performed
demonstrated
satisfying
predictability
Results:
stability
Refractive results
showed similar
stability after
procedures performed
with both laser
platforms
Conclusions:
Both systems performed similarly in
terms of safety, efficacy and
predictability. The use of the Solid
State laser for the correction of
myopia with photorefractive
keratectomy is an effective alternative
for the Excimer laser.