Distance Eso-deviation or Vergence Insufficiency

Training and experience make us think of eso-deviaitons as either partly or completely refractive in origin due to hypermetropia or an abnormal AC/A ratio. This is particularly so in children where nearby all eso-deviations are larger for near. An eso-deviaiton which is greater for distance or only present for distance seems a contradiction, so if we find one we at first think we have made a mistake.