A surgical instrument system for ophthalmic surgery in an eye is provided, comprising: an OCT apparatus including an interferometer； an optical fiber coupled to the OCT apparatus and extending a probe arm of the interferometer； a hand tool comprising: a hand piece, a tube extending away from the hand piece and comprising a distal end portion having a longitudinal axis, wherein a distal portion of the optical fiber is received within the tube； a beam emitter coupled to a tip end of the optical fiber and configured to emit an OCT measuring beam into an emission direction； and an actuator configured to change the emission direction of the OCT measuring beam relative to a tip end of the distal end portion.
