Peripheral optimized CXL and high power
Theo Seiler
Institut für Refraktive und Ophthalmo-Chirurgie (IROC )
and
University of Zürich
Seite 1
PMD
thinnest point
steepest point
Seite 2
PMD vs KC
PMD
thinnest pachymetry / μm
KC
700
500
300
Seite 3
0
0.5
1.5
1
radial distance to apex / mm
2
PMD
Seite 4
PMD
Seite 5
CXL
In the majority of the keratectasia cases
the weakest point of the cornea
that needs CXL most
is 1 to 3 mm away from the center
Seite 6
study
OCT 1 month post CXL, 10 eyes,
inhomogeneity of the beam in curve th1
relative depth in %
100
90
th
80
th1
70
mav
60
50
0
0
Seite 7
1
2
radial distance / mm
3
proposal
In order to create a homogeneous CXL-effect also in
the periphery of the cornea
irradiation with a top hat-profile is not good enough.
3 mm away from the center the light intensity needs
to be increased by at least 25%
Seite 8
profile
UV-X2000
Avedro
I0
UV-X1000
8mm
Seite 9
4mm
0
4mm
8mm
profile
Crosslinking profile of the UV-X2000
Seite 10
CXL-types
volume-type
0μm
30 min
3.00 mW/cm²
surface-type
9min
10.00 mW/cm²
100μm
200μm
300μm
400μm
500μm
600μm
Seite 11
0.1%
0.5%
30 min
2 min
CXL-types
Pseudo-Bowmans
Seite 12
CXL-types
Seite 13
CXL-types
volume-type
CXL-depth 250 to 330 μm
Seite 14
CXL-types
Applications volume-type
(homogeneous riboflavin, low power)
• infectious keratitis
• melting diseases
• keratoconus ?
Applications surface-type
(high riboflavin gradient, high power)
• refractive laser surgery
• customized CXL
Seite 15
conclusion
1. In the majority of the cases a peripheral
CXL is mandatory
2. Second generation CXL lightsources need
an optimized beam profile
3. The surface-type CXL works only if the
central irradiance guarantees an
illumination time of 10 min and less
Seite 16