Chronic use of naphazoline eye drops may cause which pupil change?

• A. Fixed, dilated pupil after repeated use
• B. Miosis
• C. No change
• D. Ptosis

Answer: (A)

Chronic topical naphazoline exposure can produce persistent dilation of the pupil because it stimulates the sympathetic (radial dilator) muscle of the iris. Prolonged vasoconstriction and adrenergic stimulation can lead to functional or structural damage to the iris muscles, so the pupil remains dilated and unreactive to light even after the drug is no longer used. This results in a fixed, dilated pupil after repeated use.

The other options don’t fit because chronic alpha-adrenergic stimulation would not cause a smaller pupil (miosis), nor would it typically show no change, and ptosis is not the classic pupil-change consequence of this mechanism.