Lid lag

Lid lag is a phenomenon that occurs secondary to lid retraction in thyroid eye disease. Various mechanisms affect the development of lid lag in thyroid eye disease (1):

• in the early stages of the disease, lid retraction is secondary to a sympathomimetic response of the eyelid muscles
• in the later stages of the disease, there are a number of possible explanations:
  • lid retraction may be associated with proptosis or fibrosis in the superior rectus – levator palpebrae superioris muscle complex or with contraction of the muscle complex counteracting a commonly existing fibrosis in the inferior rectus muscle (1)

To elicit this sign the patient should be asked to fix on the examiner's finger, held at least a metre from the patient, and not move their head. The examiner then moves the finger slowly upwards and downwards, observing the movement of the patient's eyes and eyelids. Normally they should move simultaneously; in lid lag the lids move more slowly than the eye.

Reference:

1. Traisk F, Tallstedt L. Thyroid associated ophthalmopathy: botulinum toxin A in the treatment of upper eyelid retraction--a pilot study. Acta Ophthalmol Scand. 2001 Dec;79(6):585-8.