**Question:** A 60 year old man presented with watering from his left eye since 1 year. Syringing revealed a patent drainage system. Rest of the ocular examination was normal. A provisional diagnosis of lacrimal pump failure was made. Confirmations of the diagnosis would be by:

A. Ocular ultrasound
B. Lacrimal sac tap
C. Lacrimal pump function test
D. Lacrimal sac irrigation

**Correct Answer:** C. Lacrimal pump function test

**Core Concept:**
Lacrimal pump failure is a condition where the dysfunction of the lacrimal pump mechanism results in excessive tearing. The lacrimal pump function test is a diagnostic tool used to confirm this condition.

**Why the Correct Answer is Right:**
The lacrimal pump function test is the correct answer because it directly measures the lacrimal pump function, which is the primary cause of lacrimal pump failure. This test involves applying pressure on the lacrimal sac to stimulate the lacrimal pump and observe the response, such as the reabsorption of tearing.

**Why Each Wrong Option is Incorrect:**
A. Ocular ultrasound: This test is used to evaluate the lacrimal sac and canaliculi, but it does not assess the lacrimal pump function directly.
B. Lacrimal sac tap: This procedure involves tapping the lacrimal sac, but it does not specifically test the lacrimal pump function.
D. Lacrimal sac irrigation: This test involves flushing the lacrimal sac with a saline solution, which may reveal blockage, but it does not directly assess lacrimal pump function.

**Clinical Pearl:**
The lacrimal pump function test is essential for confirming a clinical diagnosis of lacrimal pump failure. Understanding the underlying pathophysiology and performing the appropriate tests can help guide effective treatment strategies and provide appropriate management for patients with excessive tearing.