Del Mar Photonics

Optical Coherence Tomography and Femtosecond Lasers

Optical coherence tomography monitoring of vocal fold femtosecond laser microsurgery
Henning Wisweha,b, Ulrich Merkela, Ann-Kristin H¨ullera, Kathrin L¨uerßena, and Holger Lubatschowskib
a) Hannover Medical School, Clinic for Phoniatry and Paediatric Audiology,
Carl-Neuberg-Str. 1, D-30625 Hannover, Germany;
b) Laser Zentrum Hannover e.V., Hollerithallee 8, D-30419 Hannover, Germany

Surgery of benign pathological alterations of the vocal folds results in permanent disphonia if the bounderies of the
vocal fold layers are disregarded. Precise cutting with a femtosecond laser (fs-laser) combined with simultanous
imaging of the layered structure enables accurate resections with respect to the layer boundaries. Earlier works
demonstrated the capability of optical coherence tomography (OCT) for utilization on vocal folds. The layered
structure can be imaged with a spatial resolution of 10 − 20μm up to a depth of 1.5mm. The performance of
fs-laser cutting was analyzed on extracted porcine vocal folds with OCT monitoring. Histopathological sections
of the same processed samples could be well correlated with the OCT images. With adequate laser parameters
thermal effects induced only negligable damage to the processed tissue. The dimensions of the thermal necrosis
were determined to be smaller than 1μm. OCT contolled fs-laser cutting of porcine vocal fold tissue in the μm
range with minimal tissue damage is presented.

Keywords: femtosecond laser, ultra short laser pulses, OCT, optical coherence tomography, vocal folds, larynx,
microsurgery, phonosurgery, laser tissue ablation