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10% phenylephrine from minims diluted with balanced salt solution given intracamerally reduces corneal endothelium exposure to the toxic effects of sodium bisulfite

Poster Details

First Author: Y.Wong UK

Co Author(s):    A. Khan              

Abstract Details


To theoretically show that it takes less 10% phenylephrine in comparison to 2.5% phenylephrine minim drops, to create a concentration to be given intracamerally to induce mydriasis. As fewer minim drops of 10% phenylephrine are necessary, the conceal endothelium will be subjected to a lower concentration of toxic sodium bisulfite, a preservative contained in the minims.


: Theory based


Intracameral phenylephrine is now regularly used in cataract surgery for complicated cases such as floppy iris syndrome. 2.5% phenylephrine minims are routinely used and create a concentration which induces mydriasis. This theoretical review shows how less 10% phenylephrine minim needs to be used to achieve the same concentration. Reducing the number of drops would result in a lower sodium bisulphite concentration intracamerally, as this is the preservative used in phenylephrine minims. Sodium bisulfite is known to be toxic to the corneal endothelium inducing corneal oedema and a lower concentration would therefore reduce the risk of subsequent side effects.


Calculations show how less 10% phenylephrine in comparison to 2.5%, is required to create a solution with balanced salt solution to administer intracamerally :- 50mg of phenylephrine in 0.5ml = 10% 12.5mg of phenylephrine in 0.5ml = 2.5% One drop from a minim = 0.05mls Therefore One drop of 10% phenylephrine = 5mg of phenylephrine One drop of 2.5% phenylephrine = 1.25mg of phenylephrine Common practise is to use 0.25 ml of 2.5% intracamerally diluted in 1.25ml BSS, which provides us with 6.25mg of intracameral phenylephrine. To achieve a similar concentration using 10% phenylephrine would require:- Either 1 drop 10% phenylephrine = 5mg 2 drops of 10% phenylephrine = 10mg This would contain less sodium bisulfite, as less of the phenylephrine and it’s preservative agent has been used to create a similar concentration.


It requires less 10% phenylephrine minim in comparison to 2.5% phenylephrine minim to create a safe intracameral solution with BSS to induce mydriasis. By using less 10% phenylephrine the cornea is exposed to less toxic sodium bisulfite which is the preservative used in creating phenylephrine minims.

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