What is the common pathophysiology behind each of the three main etiologies for SLK?

• A. Friction
• B. Hypoxia
• C. Inflammation
• D. Infection

Answer: (A)

Repetitive mechanical irritation at the upper limbus is the central problem in SLK. The lid rubs against the superior bulbar conjunctiva and cornea, causing microtrauma to the surface. This mechanical injury triggers an inflammatory response, leading to vascular congestion, vascularized superior bulbar conjunctiva, and surface staining. The three main etiologies—often involving friction from lid-globe interaction, factors that worsen friction like contact lens wear or lid disease, and inflammatory tendencies—all share this same friction-driven mechanism. Friction is the driving force behind the tissue damage and the ensuing inflammatory changes that define SLK. Hypoxia or infection may aggravate the surface, but they do not represent the primary driver of the condition.