Strabismus (HP_0000486, a Human Phenotype Ontology id) is a misalignment of the eyes so that the visual axes deviate from bifoveal fixation. The classification of strabismus may be based on a number of features including the relative position of the eyes, whether the deviation is latent or manifest, intermittent or constant, concomitant or otherwise and according to the age of onset and the relevance of any associated refractive error. Also known as: Cross-eyed, Squint, Squint eyes.