Lacrimal Drainage Resistance Study

Epiphora, or uncontrolled tearing of the eyes, represents a common presenting complaint of patients seen by ophthalmologists. Epiphora may be due to non-obstructive causes, such as tear hypersecretion or functional tear pump failure, or obstructive causes. Functional tear pump failure may result from malposition of the eyelids, such as an abnormal out-turning (ectropion) or in-turning (entropion) of the eyelid. Currently methods to diagnose partial nasolacrimal duct obstruction are purely qualitative in nature. Our research goal is to quantitatively measure the pressure generated during conventional probing and irrigation (P\&I), and to measure the resistance to irrigation of the nasolacrimal drainage system. The investigators will measure the pressure generated during conventional P\&I using a disposable in-line pressure transducer. In addition, the investigators will use a syringe pump to deliver a constant flow rate of saline through a nasolacrimal cannula and measure the steady state irrigation pressure using the in-line transducer and digital pressure monitor. Resistance can be directly calculated from the known flow rate and pressure measurements. The investigators will compare both the pressure generated during P\&I and the lacrimal drainage resistance between patients with lacrimal drainage obstruction and controls patients with no obstruction (functional tear pump failure) as determined by clinical exam. Clinical applications for measuring lacrimal drainage resistance include quantifying partial nasolacrimal duct obstruction, guiding the choice of surgical procedure, and determining the success of lacrimal drainage procedures.