Which medication is described as having a red cap and a duration of 7-10 days?

• A. Atropine
• B. Timolol
• C. Dorzolamide
• D. Latanoprost

Answer: (A)

Long-acting mydriatics are identified by their extended duration of pupil dilation and often by color coding on packaging. Atropine is a strong antimuscarinic used to dilate the pupil and to paralyze accommodation (cycloplegia). Its effects last about 7–10 days, which is much longer than other common eye drops. The red cap is a convention used to signal these long-acting agents, helping clinicians pick the appropriate drug for goals like sustained dilation.

The other medications listed are not long-acting dilators: Timolol and Dorzolamide are glaucoma medications with shorter, hours-to-a-day durations and serve to reduce intraocular pressure, not to induce prolonged dilation and cycloplegia. Latanoprost is a prostaglandin analogue for chronic IOP lowering with once-daily dosing, and it does not produce the prolonged dilation associated with atropine.