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Dilution of Proparacaine in Balanced Salt Solution Reduces Pain of Anesthetic Instillation in the Eye

Author: Brady MD; Hustead RR; RobinsonRH; Becker KE Jr, Department of Anesthesiology, University of Kansas School of Medicine-Wichita 67214

Publication: Reg Anesth 1994 May-Jun;19(3):196-8

BACKGROUND AND OBJECTIVES: Proparacine (P), 0.5%, is often applied topically to the eye to diminish the pain of injection of anesthetic for eye surgery; however, application of 0.5% P itself can cause some degree of discomfort. This study evaluated the use of balanced salt solution to dilute P before instillation in the eye to prevent discomfort.

METHODS: In a double-blinded manner, 42 consenting adults about to undergo cataract surgery were given 0.5% P in one eye and 0.03% P in the other eye. One minute later the same solutions were instilled into each eye. Ten minutes later, 0.5% P was instilled into both eyes. After each instillation the patients were asked to describe the pain in each eye on a 0 to 10 scale.

RESULTS: Those receiving 0.5% as the first drop had a mean score of 1.28, which was greater than the score of 0.09 for the 0.03% P group (P<.01). No one reported pain after the second drop was applied 1 minute later. After receiving 0.5% P 10 minutes later, the group that received 0.5% P reported a mean pain score of 0.09 while those who had received 0.03% P reported a score of 0.76, which was significantly greater than that reported by the 0.5% P group after the 10 minute instillation (P<.01) but significantly lower than the score reported after the first instillation of 0.5% P (P<.05). CONCLUSIONS: Dilution of P in balanced salt solution to a concentration of 0.03% produces a solution that is significantly less painful than 0.5% P and reduces the discomfort of the instillation of 0.5% P.

While working at Bethlehem Steel, I had many opportunities to use the Morgan Lens.  The employees frequently splashed solutions into their eyes.  The Morgan Lens helped us irrigate their eyes promptly and efficiently.  We could seat belt the employee/patient into the van, check his eyes, pop in the Morgan Lens, hook up the I.V. bag.  While transporting him to the dispensary, his eyes were being irrigated.  Prompt irrigation with the Morgan Lens in route to the dispensary helps prevent eye damage.

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