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Milap Mehta, Julian D. Perry; Method for Measuring Lacrimal Drainage Resistance. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6758.
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Epiphora represents a common presenting complaint seen by ophthalmologists. Currently methods to evaluate nasolacrimal duct obstruction give mainly qualitative measures.
We performed a prospective review of a case series. Data was collected on age, gender, duration of symptoms, dye disappearance testing results, percentage of irrigation through the nasolacrimal duct, eyelid laxity, presence of ectropion, and the various pressure measurements.We quantitatively measured the pressure generated during manual, conventional probing and irrigation using a standard 3 cc syringe and experimental probing and irrigation using an infusion pump to deliver a constant flow rate of saline. We measured the steady state irrigation pressure using a disposable in-line pressure transducer with integrated pressure sensor (Biotrans Disposable Pressure Measuring System) and digital pressure monitor (Eagle 3000 patient monitor). Resistance was calculated from the known flow rate and pressure measurements. We compared pressure generated and resistance between patients with lacrimal drainage obstruction and control patients with no obstruction as determined by clinical exam and dye disappearance testing.
During conventional testing, manual pressure was estimated to deliver 1 cc of saline over an average of 30 seconds for a flow rate of 0.033 milliliters per second. During experimental testing, the syringe pump delivered saline over a flow rate of 0.028 milliliters per second (a known rate of 100 milliliters per hour).Seventeen patients (3 non-obstructive, 14 obstructive) underwent bilateral testing via both conventional probing and irrigation and experimental probing and irrigation via a syringe pump delivery system. The average pressure for conventional non-obstructive patients was 102 mmHg (range, 46 to 200 mmHg) and calculated resistance was 3078 mmHg x sec/ml. The average pressure for experimental non-obstructive patients was 78 mmHg (range, 12 to 209 mmHg) and calculated resistance was 2775 mmHg x sec/ml.The average pressure for conventional completely obstructed patients was 147 mmHg (range, 71 to 242 mmHg) and calculated resistance was 4467 mmHg x sec/ml. The average pressure for experimental completely obstructed patients was 92 mmHg (range, 36 to 186 mmHg) and calculated resistance was 3282 mmHg x sec/ml.
This method using a disposable in-line pressure transducer and monitor accurately measures lacrimal drainage pressure. Clinical applications for measuring lacrimal drainage resistance include quantifying nasolacrimal duct obstruction, guiding the choice of surgical procedure, and determining the success of lacrimal drainage procedures. This technique may become an adjunct to tearing evaluation.
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