Short acting mydriatic used in fundoscopy is:
**Core Concept**
Mydriasis is the dilation of the pupil, which is essential in fundoscopy to visualize the posterior segment of the eye. Short-acting mydriatics are used to achieve this temporary dilation without causing prolonged discomfort or complications.
**Why the Correct Answer is Right**
Tropicamide is a short-acting antimuscarinic agent that works by competitively inhibiting muscarinic receptors in the iris sphincter muscle. This leads to relaxation of the iris sphincter, resulting in pupil dilation. Tropicamide has a rapid onset of action and a short duration of effect, making it ideal for fundoscopic examinations.
**Why Each Wrong Option is Incorrect**
**Option A:** Cyclopentolate is a longer-acting antimuscarinic agent used for diagnostic purposes, making it less suitable for short-term use in fundoscopy.
**Option B:** Phenylephrine is an alpha-adrenergic agonist that causes vasoconstriction and mydriasis but is not typically used for short-term diagnostic purposes due to its potential side effects.
**Option C:** Atropine is a long-acting antimuscarinic agent that can cause prolonged mydriasis, making it unsuitable for short-term use in fundoscopy.
**Clinical Pearl / High-Yield Fact**
Tropicamide can be used in combination with phenylephrine to enhance mydriasis and cycloplegia, but this should be done with caution to avoid excessive side effects.
**Correct Answer:** C. Tropicamide.