Question

An old lady with painful red eye is disturbed in sleep. On examination, a small 3mm red mass is found in the limbus surrounded by blood vessels. Does the mass blanch when phenylephrine is applied?

1) Yes
2) No
3) Cannot be determined

Answer 1

The red mass in the limbus with surrounding blood vessels likely represents an ocular nodule, which does not blanch when phenylephrine is applied, because phenylephrine induces mydriasis and does not affect these blood vessels.

Step-by-step explanation:

The presence of a small 3mm red mass in the limbus surrounded by blood vessels suggests a nodule that may be associated with ocular inflammation, commonly referred to as a pterygium or pinguecula. When phenylephrine is applied, these nodules do not typically blanch. Phenylephrine is a sympathomimetic agent that induces mydriasis by acting on the adrenergic receptors in the iris's radial muscle, which results in pupillary dilation and is not designed to affect the blood vessels occurring in conjunctival nodules.

If the mass blanches (loses color) when phenylephrine is applied, it suggests that the mass is vascular in nature, meaning it is composed of blood vessels. Given the described properties of the mass and the surrounding blood vessels, and considering the mechanism of action of phenylephrine, the most accurate response is: No, the mass would not blanch when phenylephrine is applied.