Objective: Distance between the medial and lateral canthi is more than 2 SD below the mean for age
Subjective: Apparently reduced length of the palpebral fissures
Measurement techniques and norms are as specified in Hall et al.  and Farkas . These sources include more complete data for Caucasians than for other groups. Decreased palpebral fissure length may be accompanied by a decreased vertical distance between the upper and lower eyelid, which gives the eyes a more slit-like appearance and may give the appearance of Ptosis, but this should be coded separately if it is present. Severe shortening of the palpebral fissures leads to Blepharophimosis.