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Dilution of Proparacaine in Balanced Salt Solution Reduces Pain of Anesthetic Instillation in the Eye
  1. Mark D. Brady, M.D.,
  2. Robert R. Hustead, M.D.,
  3. Robert H. Robinson, M.D. and
  4. Karl E. Becker Jr.,, M.D.
  1. From the Department of Anesthesiology, University of Kansas School of Medicine-Wichita, Wichita, Kansas
  1. Reprint requests: Dr. Karl Becker, Jr., Department of Anesthesiology, University of Kansas School of Medicine-Wichita, 1010 N Kansas, Wichita, KS 67214.


Background and Objectives. Proparacaine (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 pain 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 had 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.

  • topical anesthetics
  • cataract surgery ophthalmic preparations
  • balanced salt solution
  • pH
  • proparacaine

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