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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.

Thanks for the opportunity to sing the praises of the Morgan Lens! Those of us who have been in the field for a while wonder what we ever did without them!  We find two general uses for the lenses.   One is for contact irritation:  most typically, splashes.  After local anesthetic, for ease of insertion, the lenses fit comfortably on patients of all ages and provide gentle and thorough irrigation of irritant substances. We have many cases of this type.  The second most common use is for patients show suffer multiple injuries due to automobile accidents, major trauma, burns, falls, etc.  Not only does the lens thoroughly irrigate the eye, removing most or all of the debris that has accumulated, it more importantly frees up the nurse's hands so that she can perform other lifesaving functions.  Quite frankly, eye irrigation was treated as "the bottom of the list" often because other patient's other injuries were more devastating with higher morbidity and mortality.  Particularly in the burn patient, the soothing effect of the irrigation and potential to prevent infection or further injury, make it an easy to use, valuable asset for patient care.

Registered Nurse (Montana)

MorTan Inc.

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Why Use The Morgan Lens?

The Morgan Lens is used in 90% of hospital emergency departments in the USA and can be inserted in less than 20 seconds. There simply is no other "hands-free" method of eye irrigation. Nothing else frees medical personnel to treat other injuries or to transport the patient while irrigation is underway. Nothing is more effective at treating ocular chemical, thermal, and actinic burns or removing non-embedded foreign bodies, even when the patient's eyes are closed tightly. Its design makes it simple and straightforward to use so minimal training is required.