Transcript Document

DR. KUMAR J DOCTOR
Title:
Intra Operative Online Pachymetry in
LASIK with Wavefront-Guided Ablation
Optical Coherence Pachymetry with the ESIRIS
DOCTOR EYE INSTITUTE
ANDHERI
MUMBAI
[email protected]
NO FINANCIAL INTEREST
Purpose:
To investigate Intraoperative Optical
Coherence Pachymetry during various
steps of LASIK while treating patient
with Wavefront Guided Ablation
Online OCP Optical Coherence Pachymeter
ESIRIS SCHWIND LASER
mirror
light source beam
splitter
s(t)
eye
detector
OCP-signal from Michelson Interferometer
The direct integration of Online
Pachymetry into the ESIRIS
It comes with fiberglass
coupling and through
Automated
measurements of
changes in corneal
thickness, allows
continuous and real time
values with 10
measurements per
second, without having
to interrupt the
treatment.
LASIK-Cut
Pre-cut
Post-cut
540 µm
394 µm
0 µm
t
The reproducibility of current
System is 1 to 2 microns.
Method
25 patients IN Aug. 09
 Myopic Eyes
 Corneal Thickness Assessed During
Various Steps
CP Microkeratome
 110 micron head – 50 eyes
One Blade Used Per Eye
Wave Front Guided Treatments done

Flap Open
Ablation
Flap Closed
The data signal:
503 µm
Front cornea surface
2,2
2
Back surface cornea
1,8
1,6
1,4
1,2
1
0,8
Scan over time
503 µm
t
Signal
Wavefront-Guided Ablation
Every 3 micron distortion on the Cornea creates
1 micron of Wavefront Error “Corneal Wavefront is
the component of eye refraction owed to the
Cornea (or OPTICAL PATH DIFFERENCE OPD)
Aberrations:
“Ocular” = “Corneal” + “Internal”(or “Total”)
From WA
From TC
(100%)
(80%)
Results
Mean Spherical Equivalent - 4.0 D,+/3.0 D
 Mean Stromal Depth 80+/-22 microns
 Mean Flap Thickness of 110, +/- 9
microns
 Residual Stromal 300 microns &
above in all eyes.
 All optical zones 6.00 mm

Table 1 Central corneal thickness measurements in
eyes PRE-OP laser in situ keratomileusis
Devices
Mean SD [M
Range [M
On Line Pachy
502.8
431-599
Table 2 Central corneal thickness measurements in
eyes POST-OP laser in situ keratomileusis
Devices
Mean SD [M
Range [M
On Line Pachy
438
463-512
Advantages of Online Pachymetry.
The greatest advantage of Online Pachymetry is indeed the
improved quality assurance, objective monitoring of the
complete LASIK procedure for the first time.
The special feature of Online Pachy provides

Extensive Diagnosis – Each step of the surgery can be
checked during operation

Contact Free measurement of Corneal Thickness online,
hence no chances of infection

Also the individual ablation depth and possible dehydration
effects of the cornea were monitored continuously

Improvement in Intraoperative Safety and Quality of LASIK
Conclusion

Evaluation of residual corneal thickness is
crucial to avoid the condition of excessive corneal
thinning (ectasia)
Important safety feature to monitor the
thickness of each cut
 Assessment of flap and residual stromal
thickness.
 Accurate Measurement of ablation depth
during laser treatment.
 TO CHECK A WELL OPPOSED INTERFACE
AFTER WASH
