Various embodiments are generally directed to a surgical instrument for detecting light, such as by measuring light traveling in a waveguide, for instance. Some embodiments are particularly directed to a determining one or more parameters associated with ocular surgery based on detection of the light. In one or more embodiments, for example, a surgical instrument may include a cannula, a waveguide, a transducer, and logic implemented in circuitry communicatively coupled with the transducer. In one or more such embodiments, the cannula may comprise at least a portion of the waveguide. In some embodiments, the transducer may detect light traveling in a first direction in the waveguide. In some such embodiments, the logic may determine at least one parameter associated with ocular surgery based on the light detected by the transducer.