II. Definitions

  1. Orbicularis Paralysis
    1. Orbicularis Oculi Muscle paralysis
    2. Results in failure of Eyelid closure
  2. Lid Lag (Von Graefe Sign)
    1. Delay in closing the upper Eyelid
    2. Excess white Sclera is visible between the Eyelid and the iris (esp. when gazing downward)
  3. Lid Retraction (Dalrymple Sign)
    1. Palpebral fissure (distance between upper and lower open Eyelids) is wide, exposing excess white Sclera
    2. Results in a staring gaze appearance (typically with Sclera seen circumferentially around the iris)

III. Pathophysiology

  1. Lid Lag and Lid Retraction
    1. Results from sympathetic hyperactivity (typically due to Hyperthyroidism)
    2. Increased contractions of the Muller Muscle (Eyelid elevator)

IV. Causes: Unilateral

V. Causes: Bilateral

  1. Lid spasm from sympathetic stimulation
  2. Exophthalmos (Proptosis)
    1. Bilateral in Graves Disease
    2. Unilateral with orbital masses, Cavernous Sinus Thrombosis
  3. Hyperthyroidism
    1. Any Hyperthyroidism (e.g. Thyroiditis) may cause Lid Lag or Lid Retraction
    2. Graves Disease also causes Exophthalmos (as above)

VI. Complications

  1. Corneal Injury due to lack of protection, dryness

Images: Related links to external sites (from Bing)

Related Studies