Which diagnostic step may be used to evaluate NLDO before DCR?

• A. Visual acuity test
• B. Lacrimal irrigation
• C. Corneal topography
• D. Tonometry

Answer: (B)

Assessing the patency of the lacrimal drainage system is the key idea here. Lacrimal irrigation, also called syringing, involves gently flushing saline through the tear ducts via the puncta. By observing how the saline travels (or doesn’t travel) and whether any saline regurgitates back through the puncta, you can determine if there is an obstruction and where it lies—canalicular, lacrimal sac, or nasolacrimal duct. This information is crucial before performing a DCR, because it confirms NLDO and helps guide the surgical plan.

The other tests don’t evaluate the tear drainage pathway. Visual acuity assesses vision clarity, corneal topography maps the curvature of the cornea, and tonometry measures intraocular pressure.