Trisomy 18p is an extremely rare chromosomal anomaly with a poorly defined clinical phenotype. Reported manifestations include short stature, mild, moderate or severe developmental delay and intellectual disability, variable but mild facial dysmorphism, and epilepsy.

The upper eyelid margin is positioned 3 mm or more lower than usual and covers the superior portion of the iris (objective); or, the upper lid margin obscures at least part of the pupil (subjective).