Definition
Upper lid margin at or above superior limbus.

Differentials
Contralateral ptosis

Causes
Thyroid eye disease (#1 possibility)
Retrobulbar Space Occupying Lesion (Optic Nerve Glioma, Extraconal mass, etc.)
Unopposed levator action due to facial palsy
Aberrant regeneration of CN III
Marcus Gunn jaw winking
Dorsal Midbrain Syndrome (upgaze paralysis)
Parkinsons
Uraemia (Kidney Disease)
Congential (Duane's retraction syndrome, Down's syndrome, transient 'eye popping' in normal infants)

Primary Workup
Thyroid Panel (TSH, T3, T4 - Thyroid)

Secondary Workup (If primary results all negative)
CT (Retrobulbar Space Occupying Lesion)
MRI (Dorsal Midbrain Syndrome)
BUN/Creatinine levels (Kidney Disease)
Neuro consult (Parkinsons)