Overnight wear increases risk of which events?

• A. infectious, inflammatory
• B. allergic, mechanical
• C. vascular, retinal
• D. cosmetic, irritation

Answer: (A)

Overnight wear heightens risk because the cornea gets less oxygen and tear exchange is reduced while you sleep. This hypoxic, low-clearance environment makes the corneal surface more vulnerable to problems, especially infections and inflammation. Bacteria can more easily invade a softened, stressed epithelium, leading to infections like microbial keratitis, and the eye can mount inflammatory responses to this stress, including sterile inflammatory events. Those two categories—infectious and inflammatory—are the ones most strongly linked to wearing lenses overnight.

Allergic reactions and irritation can occur with lens wear, but they aren’t as specifically increased by sleeping in lenses. Vascular or retinal complications aren’t typical outcomes of contact lens wear, and cosmetic irritation isn’t a primary medical risk of overnight wear.