An instrument for isolating candidate eyelashes to attach prostheses includes an instrument tip which has a tip aperture. A candidate eyelash is disposed in a distal slot of the tip aperture. The instrument tip is advanced relative to the candidate eyelash and the instrument tip applies a force to eyelashes that are adjacent to the candidate eyelash. The application of the force actuates the eyelashes that are adjacent to the candidate eyelash away from the candidate eyelash. The candidate eyelash is actuated into an open area of the tip aperture and a prosthesis is attached to the candidate eyelash.