A method for determining a grade of nuclear cataract in a test image. The method includes: (1a) defining a contour of a lens structure in the test image, the defined contour of the lens structure comprising a segment around a boundary of a nucleus of the lens structure (1b) extracting features from the test image based on the defined contour of the lens structure in the test image and (1c) determining the grade of nuclear cataract in the test image based on the extracted features and a grading model.
