Assessing the accuracy of intracameral phenylephrine preparation in cataract surgery

Guthrie, S., Jensen, T., Hartley, R. C. , Ramaesh, K. and Lockington, D. (2018) Assessing the accuracy of intracameral phenylephrine preparation in cataract surgery. Eye, 32, pp. 1615-1620. (doi: 10.1038/s41433-018-0143-y) (PMID:29907787)

Abstract

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 0.2 ml 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. Methods: Phenylephrine 0.2 ml 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). Wide variability was observed across all dilution groups. 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 1 ml syringes should not be used for mixing or dilution of drug. Commercial intracameral phenylephrine products would address dosage concerns and could improve surgical outcomes in cases of poor pupil dilation and/or floppy iris syndrome.

• Item Type: Articles
• Additional Information: TJ has received studentship funding from the Engineering and Physical Sciences Research Council.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Hartley, Professor Richard and Ramaesh, Dr Kanna
• Authors: Guthrie, S., Jensen, T., Hartley, R. C., Ramaesh, K., and Lockington, D.
• College/School: College of Medical Veterinary and Life Sciences; College of Science and Engineering > School of Chemistry
• Journal Name: Eye
• Publisher: Nature Publishing Group
• ISSN: 0950-222X
• ISSN (Online): 1476-5454
• Published Online: 15 June 2018
• Copyright Holders: Copyright © 2018 The Royal College of Ophthalmologists
• First Published: First published in Eye 32:1615-1620
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher