Which of the following is NOT one of the major etiologies of SLK?

• A. Contact lens use
• B. Myasthenia Gravis
• C. Thyroid eye disease
• D. Dry eye disease

Answer: (B)

SLK happens when friction and surface irritation hit the superior bulbar conjunctiva and limbus, often from factors that increase lid–globe rubbing or reduce tear film quality. The major contributors are ongoing contact lens wear (which constantly rubs the superior bulbar area), dry eye disease (inadequate lubrication leads to more rubbing with each blink), and thyroid eye disease (lid retraction and exposure cause increased friction at the top of the eye). Myasthenia gravis, while it can cause eyelid ptosis and diplopia due to neuromuscular weakness, does not typically drive the chronic mechanical irritation at the superior limbus that defines SLK, so it isn’t considered a major etiology.