Which condition is listed as a cause of miosis?

Which condition is listed as a cause of miosis?

• A. Uveitis
• B. Drugs
• C. Glaucoma
• D. Hyphema

Answer: (A)

Miosis is pupil constriction driven by iris sphincter muscle contraction. Anterior uveitis inflames the iris and ciliary body, disrupts the blood-aqueous barrier, and causes spasm of the iris sphincter. This inflammatory process reliably produces a small, constricted pupil in horses, so uveitis is a classic disease-associated cause of miosis. Glaucoma more often leads to a larger or irregular pupil, especially in acute cases, rather than a true constricted pupil. Hyphema can irritate the eye but isn’t a primary, defining cause of miosis. Drugs can induce miosis pharmacologically (miotics), but that’s a medication effect rather than a disease condition. Thus, the condition most consistently listed as a cause of miosis among these options is uveitis.

Miosis is pupil constriction driven by iris sphincter muscle contraction. Anterior uveitis inflames the iris and ciliary body, disrupts the blood-aqueous barrier, and causes spasm of the iris sphincter. This inflammatory process reliably produces a small, constricted pupil in horses, so uveitis is a classic disease-associated cause of miosis.

Glaucoma more often leads to a larger or irregular pupil, especially in acute cases, rather than a true constricted pupil. Hyphema can irritate the eye but isn’t a primary, defining cause of miosis. Drugs can induce miosis pharmacologically (miotics), but that’s a medication effect rather than a disease condition. Thus, the condition most consistently listed as a cause of miosis among these options is uveitis.