An apparatus for cutting a tissue part of an eye by means of laser radiationincludesa suction-ring unit which is capable of being mounted onto the eye, with aring axis,a mechanical interface unit which is separate from the suction-ring unit,which iscapable of being moved along the ring axis in coupling contact with thelatter, andwhich is capable of being mechanically coupled with optical means which focusthelaser radiation onto or into the tissue part of the eye, and sealing meanswhich uponmovement of the interface unit in couping contact with the suction-ring unitform aspace which is capable of being evacuated and which is delimited by sealingsurfaces of the interface unit and of the suction-ring unit and of the sealingmeans.
