def calculate_point_of_interest(center_of_cornea_curvature, visual_axis_unit_vector, z_shift):
    """
    Calculates point of interest.
    Based on formula 2.31 and 3.61 calculations.

    :param center_of_cornea_curvature: center of cornea curvature
    :param optic_axis_unit_vector: unit vector of optic axis
    :param z_shift: z offset of the screen
    """

    # Formula 3.61
    kg = (z_shift - center_of_cornea_curvature[2]) / visual_axis_unit_vector[2]

    # Formula 2.31
    point_of_interest = center_of_cornea_curvature + kg * visual_axis_unit_vector

    return point_of_interest