INTRA OPERATIVE ONLINE PACHY METRY –A SAFETY TOOL Dr. KUMAR J DOCTOR DOCTOR EYE INSTITUTE MUMBAIINDIA 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. 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. 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 beam splitter light source detector eye s(t) OCP-signal from Michelson Interferometer

The direct integration of Online Pachymetry into the AMARIS It comes with fiberglass coupling and through Automated and through Automated measurements of changes in Corneal thickness, allows continuous and real time values with 10 measurements per with 10 measurements per second, without having to interrupt the treatment. The reproducibility of current System is 1 to 2 microns.

OCPRECORDINGDURINGSURGERY

Purpose : To investigate Intraoperative Optical Coherence Pachymetry during various steps of Laser in Situ Keratomileusis (LASIK) 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. 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 spherical equivalent refraction was – 5.0 D, +/- 4.0 D. Mean stromal depth of 100 +/- 18 µ was ablated. Mean stromal depth of 100 +/- 18 µ was ablated. Mean flap thickness was 90 µ, +/-9 µ. Mean flap thickness was 90 µ, +/-9 µ. Residual corneal stromal bed of more than 300 microns was preserved in all cases. Residual corneal stromal bed of more than 300 microns was preserved in all cases. The immediate post op showed swelling of the cornea. The immediate post op showed swelling of the cornea.

Results The flap thickness measured by OCP and OCT post I month.

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. 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. 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. Prevents itrogenic corneal ectasia in patient with thin corneas. Increases the efficiency, predictability and safety of the procedure. Increases the efficiency, predictability and safety of the procedure.