II. Definitions
- Orbicularis Paralysis
- Orbicularis Oculi Muscle paralysis
- Results in failure of Eyelid closure
- Lid Lag (Von Graefe Sign)
- Lid Retraction (Dalrymple Sign)
III. Pathophysiology
- Lid Lag and Lid Retraction
- Results from sympathetic hyperactivity (typically due to Hyperthyroidism)
- Increased contractions of the Muller Muscle (Eyelid elevator)
IV. Causes: Unilateral
V. Causes: Bilateral
- Lid spasm from sympathetic stimulation
-
Exophthalmos (Proptosis)
- Bilateral in Graves Disease
- Unilateral with orbital masses, Cavernous Sinus Thrombosis
-
Hyperthyroidism
- Any Hyperthyroidism (e.g. Thyroiditis) may cause Lid Lag or Lid Retraction
- Graves Disease also causes Exophthalmos (as above)
VI. Complications
- Corneal Injury due to lack of protection, dryness