Purchase this article with an account.
C. Lewis, W. J. Dupps, J. D. Perry; Method for Measuring Lacrimal Drainage Resistance. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3149.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To validate a technique for measuring the resistance of the lacrimal drainage system during irrigation.
We simulated various degrees of nasolacrimal duct obstruction using either a nasolacrimal cannula or needles of various gauge and length. The nasolacrimal cannula simulated a completely patent lacrimal drainage system, while a ½-inch 30-gauge needle simulated a nearly occluded system. A syringe pump delivered a constant flow rate of saline. We measured the steady state irrigation pressure using an in-line transducer and digital pressure monitor. Resistance was calculated from the flow rate and pressure measurements. We obtained four measurements under each of five simulated conditions.
The syringe pump delivered 2 cc of saline over an average of 23.1 seconds, for a flow rate of 0.086 cc/sec. The average pressure using the nasolacrimal canula was 27.25 +/- 0.5 mmHg and the calculated resistance was 317 mmHg x sec/ml. The average pressure using a 3/8 inch 26 gauge needle was 78.25 +/- 0.5 mmHg and the calculated resistance was 910 mmHg x sec/ml. The average pressure using a 1/2 inch 27 gauge needle was 180.25 +/- 7.1 mmHg and the calculated resistance was 2096 mmHg x sec/ml. The average pressure using a 1 1/2 inch 25 gauge needle was 223.75 +/- 1.5 mmHg and the calculated resistance was 2602 mmHg x sec/ml. The average pressure using a ½ inch 30 gauge needle was over 300 mmHg and the calculated resistance was therefore over 3488 mmHg x sec/ml. Above 300 mmHg the syringe pump signals ‘occluded’ and flow is stopped.
We can successfully measure the resistance to irrigation over a range of simulated obstructive conditions. 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. This method may be easily adapted to clinical use and is being explored as an adjunct technique for evaluating and managing the tearing patient.
This PDF is available to Subscribers Only