**Question:** Positive fluorescein dye disappearance test indicates that watering eye is due to:

A. Lacrimal gland dysfunction
B. Conjunctival disease
C. Trauma
D. Corneal disease

**Correct Answer: A. Lacrimal gland dysfunction**

**Core Concept:**
The fluorescein dye disappearance test is a diagnostic test used to evaluate the function of the lacrimal gland, which is responsible for producing tears. The test involves applying a fluorescent dye to the eye and observing its disappearance from the tear film over time. A normal test would demonstrate a rapid disappearance of the dye due to efficient tear production and drainage.

**Why the Correct Answer is Right:**
A positive test indicates a delay or failure in tear drainage. This could be due to obstruction or dysfunction of the lacrimal drainage system, including the lacrimal sac, canaliculi, and nasolacrimal duct. In this case, the lacrimal gland is still producing tears, but the drainage system is unable to remove them efficiently.

**Why Each Wrong Option is Incorrect:**
A. Lacrimal gland dysfunction: This is the correct answer, as mentioned earlier.
B. Conjunctival disease: Conjunctival disorders may cause ocular surface abnormalities but do not directly affect tear drainage.
C. Trauma: Trauma could potentially impair tear production or drainage, but a positive fluorescein dye disappearance test is not exclusively caused by trauma.
D. Corneal disease: Corneal disorders mainly affect the cornea and do not directly impact tear drainage.

**Clinical Pearl:**
A positive fluorescein dye disappearance test should raise suspicion for lacrimal gland dysfunction, such as in cases of Sjögren's syndrome, a common autoimmune disorder affecting the lacrimal gland. Early diagnosis and management of such conditions are essential to preserve ocular surface health and prevent complications related to dry eye disease.