A method of determining a correction for distortion in eye representations of an ophthalmoscope comprising (i) constructing an optical description of a system comprising the ophthalmoscope and a model eye, (ii) passing a ray through the system onto a surface of the model eye, (iii) calculating an actual measurement of the ray at the surface, (iv) determining a horizontal scanning angle and a vertical scanning angle of the system for the ray, (v) calculating an expected measurement of the ray at the surface using the horizontal scanning angle and vertical scanning angle of the system, (vi) repeating steps (ii) to (v) for a plurality of further rays, and (vii) comparing the actual measurements of the rays at the surface with corresponding expected measurements of the rays at the surface to determine the correction for distortion in eye representations of the ophthalmoscope.
