INTRA OPERATIVE ONLINE PACHY METRY –A SAFETY TOOL Dr. KUMAR J DOCTOR DOCTOR EYE INSTITUTE MUMBAI INDIA NO FINANCIAL INTEREST
Feb 24, 2016
INTRA OPERATIVE ONLINE PACHY METRY –A SAFETY TOOL
Dr. KUMAR J DOCTORDOCTOR EYE INSTITUTE MUMBAI INDIA NO FINANCIAL INTEREST
On line pachymetry
Is a high resolution non contact method
which enables the corneal thickness changes to be measured intra operatively during all steps of the surgery.
It adds new safety dimensions to Lasik.
Importance OF OCP
Is in patients with Thin corneas High refractive errors Who need enhancement and
retreatments Fear of keratectasia
Online OCP Optical Coherence Pachymeter
AMARIS SCHWIND LASER
mirror
beamsplitter
light source
detector
eye
s(t)
OCP-signal from Michelson Interferometer
The direct integration of Online Pachymetry into
the AMARISIt comes with fiberglass coupling and through Automatedmeasurements of changes in Corneal thickness, allowscontinuous and real time values with 10 measurements persecond, without havingto interrupt thetreatment.
LASIKLASIK--CutCutPre-cut
540 µm394 µm
0 µm
t
Post-cut
The reproducibility of current System is 1 to 2 microns.
OCPRECORDING DURING SURGERY
Purpose:
To investigate Intraoperative Optical Coherence Pachymetry during various steps of Laser in Situ Keratomileusis (LASIK)
Method: With the Integrated Online Pachymetry 50
patients with Myopia were studied. LASIK was performed with 90 micron head for
all eyes using Carriazo Pendular Microkeratome. Online pachymetry measures the corneal
thickness before and after lifting the flap AUTOMATICALLY .
This reading was subtracted from the one before flap creation to get accurate flap thickness.
Post-op 1 month OCT for Flap thickness was done for every eye.
Observation Mean spherical equivalent refraction was – 5.0 D, +/-
4.0 D . Mean stromal depth of 100 +/- 18 µ was ablated. Mean flap thickness was 90 µ, +/-9 µ. Residual corneal stromal bed of more than 300
microns was preserved in all cases.
The immediate post op showed swelling of the cornea.
ResultsThe flap thickness measured by OCP
and OCT post I month.
Mean Thickness of Flap by OCP Mean Thickness of flap by OCT85
86
87
88
89
90
91
92
93
90 90
Thic
knes
s in
Mic
rons
Discussion Efficiency and safety of lasik procedure has
increased with the integrated OCP. Further horizons are widened for treatment of
thin corneas , to prevent keratectasia This has proved extremely beneficial in cases
that require retreatment or enhancement . OCP is a great link with the Excimer Laser
Conclusion:The real time online pachymetry being
non contact takes measurement through all steps of the surgery .
This is an important safety feature for monitoring flap thickness with each cut and to check residual stromal thickness.
Prevents itrogenic corneal ectasia in patient with thin corneas.
Increases the efficiency, predictability and safety of the procedure .