Dilution of proparacaine in balanced salt solution reduces pain of anesthetic
instillation in the eye.
Author(s): Brady MD, Hustead RR, Robinson RH, Becker KE Jr.
Affiliation(s): Department of Anesthesiology, University of Kansas School of Medicine-Wichita
67214.
Publication date & source: 1994, Reg Anesth. , 19(3):196-8
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.
|