Quiz Form

Question Date: 16/09/2023

Question: Which of these eye signs is not consistent with ocular myasthenia gravis?

Options:

• Internuclear opthalmoplegia like weakness
• Covering of ptotic eye relieves frontalis contraction
• Fast saccades producing eyelid quiver
• Passively lifting the ptotic eye causes no change in opposite lid retraction

Correct Answer: Passively lifting the ptotic eye causes no change in opposite lid retraction

Explaination: There are myriad of eye signs described in ocular myasthenia gravis. Pseudo internuclear opthalmoplegia type weakness is described as the medial rectus is most often involved. Saccades may be fast, producing ocular quiver. After downgaze, upgaze may produce lid overshoot (cogans lid twitch). In asymmetric ptosis, covering the ptotic eye relieves opposite frontalis contraction and passively lifting the ptotic lid causes opposite lid to fall (curtain sign) based on Herings law. This is unlike the plus minus syndrome caused by midbrain infarct, where passively lifting the ptotic eyelid causes no effect on opposite eyelid retraction. The caveat to this distinction is presence of concomitant thyroid eye disease which may cause lid retraction. On prolonged forceful eye closure, the eyes open, exposing the sclera (peek sign)

Reference: Nair AG et al. Ocular myasthenia gravis A review. Indian J Opthalmol 201462(10)985-991.