What is the most common EOM affected by Thyroid Eye Disease?

What is the most common EOM affected by Thyroid Eye Disease?

• A. Inferior rectus
• B. Medial rectus
• C. Superior rectus
• D. Lateral rectus

Answer: (A)

Thyroid Eye Disease causes inflammatory enlargement and eventual fibrosis of extraocular muscles, with a typical pattern where the inferior rectus is affected most often. When the inferior rectus becomes tight and fibrotic, upgaze is restricted, leading to vertical diplopia and a downward drift of the affected eye in primary position. This makes the inferior rectus the most commonly involved muscle, more so than the other recti, which explains why it’s the best choice. The other muscles can be involved later, but not as frequently as the inferior rectus.

Thyroid Eye Disease causes inflammatory enlargement and eventual fibrosis of extraocular muscles, with a typical pattern where the inferior rectus is affected most often. When the inferior rectus becomes tight and fibrotic, upgaze is restricted, leading to vertical diplopia and a downward drift of the affected eye in primary position. This makes the inferior rectus the most commonly involved muscle, more so than the other recti, which explains why it’s the best choice. The other muscles can be involved later, but not as frequently as the inferior rectus.