Assessing the accuracy of intracameral phenylephrine preparation in cataract surgery

Session Details

Session Title: Cataract Surgery & Glaucoma

Session Date/Time: Sunday 23/09/2018 | 14:00-16:00

Paper Time: 15:26

Venue: Room A3, Podium 1

First Author: : S.Guthrie UK

Co Author(s): :    T. Jensen   R. Hartley   K. Ramaesh   D. Lockington           

Abstract Details

Purpose:

Unpreserved phenylephrine is often used as an off-licence intracameral surgical adjunct during cataract surgery to assist with pupil dilation and/or stabilise the iris in floppy iris syndrome. It can be delivered as a neat 0.2ml bolus of either 2.5% or 10% strength, or in a range of ad-hoc dilutions. We wished to assess the accuracy of intracameral phenylephrine preparation in clinical practice.

Setting:

Tennent Institute of Ophthalmology, Glasgow, UK.

Methods:

Phenylephrine 0.2ml was analysed both neat (2.5% and 10%) and in diluted form (ratio of 1:1 and 1:3). Samples were analysed using the validated spectrophotometric method.

Results:

A total of 36 samples were analysed. The standard curve showed linearity for phenylephrine (R2 = 0.99). There was wide variability observed in all the different dilution groups when compared with the expected results, particularly with the 1:3 dilution, as the 95% confidence intervals didn’t contain the target values. There was evidence of significant differences in the percentage deviations from intended results between dilutions (p<0.001). Mean percentage deviation for 1:3 dilution was significantly greater than neat (p=0.003) and 1:1 dilution (p=0.001). There was no evidence of a significant difference between 1:1 and neat (p=0.827).

Conclusions:

Current ad-hoc dilution methods used to prepare intracameral phenylephrine are inaccurate and highly variable. Small volume 1ml syringes should not be used for mixing or dilution of drug. Using commercial intracameral phenylephrine products would address this problem and improve surgical outcomes in cases of poor pupil dilation and/or floppy iris syndrome.

Financial Disclosure:

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