1. A method, comprising: receiving a light beam from a model eye at an optical measurement instrument having an optical axis; producing image data, including light spot data for a plurality of light spots, from the received light beam; determining an observed location of a corneal reflex from the model eye within an image representing the image data; and determining an angle of misalignment between an axis normal to a front surface of the model eye and the optical axis of the optical measurement instrument from the observed location of the corneal reflex within the image, wherein determining the angle of misalignment between the axis normal to the front surface of the model eye and the optical axis of the optical measurement instrument from the determined location of the corneal reflex within the image comprises: establishing an expected location of the corneal reflex within the image; and using a ray tracing algorithm to calculate the angle of misalignment between the expected location and the observed location.