Question

Which of the following drug can produce mydriasis without cycloplegia?

• A. Atropine
• B. Tropicamide
• C. Homatropine
• D. Ephedrine

Answer 1

The Correct Option is D

To determine which drug can produce mydriasis (pupil dilation) without causing cycloplegia (paralysis of the ciliary muscle, leading to loss of accommodation), we need to understand the actions of each drug listed in the options.

1. Atropine: Atropine is a well-known anticholinergic drug that blocks acetylcholine, resulting in both mydriasis and cycloplegia. This drug paralyzes the ciliary muscle, thus causing a loss of accommodation.
2. Tropicamide: Similar to atropine, tropicamide also acts as a mydriatic and cycloplegic. It is commonly used in eye examinations to dilate the pupil and temporarily paralyze accommodation.
3. Homatropine: This is another anticholinergic agent that causes both mydriasis and cycloplegia. It has a shorter duration of action compared to atropine but still affects the ciliary muscle.
4. Ephedrine: Ephedrine is an adrenergic drug that primarily stimulates adrenergic receptors. It leads to mydriasis due to the stimulation of alpha-adrenergic receptors in the eye but does not affect the ciliary muscle significantly, thus not causing cycloplegia.

Based on the above analysis, Ephedrine is the correct answer as it can produce mydriasis without cycloplegia. The other drugs listed are anticholinergics that typically paralyze the ciliary muscle, leading to cycloplegia along with pupil dilation.

To summarize, mydriasis without cycloplegia is usually produced by adrenergic agents like ephedrine, which act on adrenergic receptors, whereas anticholinergic drugs affect both mydriasis and accommodation.