A method and apparatus for aligning a two-dimensional eye image with a predefined axis by rotation at a rotation angle are disclosed, the method comprising deriving the rotation angle and a de-noised image, which minimises a cost function comprising (i) a complexity measure of the de-noised image and (ii) magnitude of a noise image obtained by rotating the first image by the rotation angle and subtracting the de-noised image. Related methods and apparatus are disclosed for aligning a plurality of images with the predefined axis before alignments in transverse and parallel directions, as well as averaging the aligned images, in further embodiments, a method and apparatus of determining angle closure are disclosed, using a database of reference eye images with and without eye closure, the method comprising obtaining a two dimensional eye image, determining respective weights for each reference images that minimise a cost function comprising the difference between the received image and sum of the weighted reference images； identifying at least one of the first and second reference images having least differences with received image and determining whether the eye exhibits eye closure based on the received image being closer to first or second weighted reference images.
