The safety of intracameral phenylephrine - A systematic review

Cardiovascular effects of diluted intracameral combination of 0.02% tropicamide, 0.31% phenylephrine, and 1% lidocaine during phacoemulsification to manage intraoperative miosis

PURPOSE

Intracameral mydriatic agents (ICMAs) are replacing the conventional method of topical mydriasis for its fast action and no need for repeated instillation before cataract surgery. Its application for the management of intraoperative miosis needs to be studied with different doses of mydriatic agent. The objective of the study is to study cardiovascular effects of diluted intracameral combination of 0.02% tropicamide, 0.31% phenylephrine, and 1% lidocaine during phacoemulsification to manage intraoperative miosis.

MATERIALS AND METHODS

The study was conducted at Mojiram Lions Eye Hospital Akbarpur Majra village, Palla Bakhtawarpur Road, Delhi, during the year 2021-2022 after taking approval from the Ethical Committee of the hospital. Patients undergoing cataract surgery who were not dilated adequately during the preoperative period or developed intraoperative miosis were managed by injecting diluted intracameral combination of 0.02% tropicamide, 0.31% phenylephrine, and 1% lidocaine (phenocaine plus). 0.5 ml of phenocaine plus was diluted with 1.5 ml of ringer lactate solution and 0.50 ml of this solution was injected intracameral and its effect on pulse rate, blood pressure (BP), and oxygen saturation were monitored continuously on pulse oximeter.

RESULTS

There was no statistically significant effect of diluted ICMA (Phenocaine Plus) on diastolic BP and oxygen saturation. However, systolic BP showed a little change from mean of 133.78 (standard deviation [SD] =16.04) mmHg to 133.92 (SD = 15.33) mmHg which was statistically significant but clinically not significant. Pulse rate increased slightly from mean 76.46 per minutes (SD = 15.14) to 79.40 (SD = 14.95) at 10 s and 76.49 (SD = 15.15) at 60 s. The difference was again statistically significant but clinically insignificant.

CONCLUSION

Low concentration of intracameral combination of 0.02% tropicamide, 0.31% phenylephrine, and 1% lidocaine is a very safe and effective method for the management of intraoperative miosis.

Intracameral phenylephrine for surgical mydriasis and intraoperative floppy-iris syndrome: systemic adverse effects and optimal dose

Phenylephrine, a potent sympathomimetic, induces mydriasis via iris dilator muscle contraction. Intracameral (IC) phenylephrine has been successfully used in cataract surgery for initial mydriasis, maintaining mydriasis, and management of intraoperative floppy-iris syndrome. Serious systemic adverse events (mainly cardiovascular) have been described with topical phenylephrine drops, but we found very little evidence of such adverse events associated with IC phenylephrine use. However, we suspect under-reporting of such adverse events, as they may instead be ascribed to anxiety, positioning, anesthesia, etc. Optimal dosage/concentrations for IC phenylephrine use in different purposes have not been fully studied. In the absence of robust evidence, we suggest that lower but effective IC phenylephrine concentrations are used: a lower concentration (0.31%), in conjunction with an anticholinergic and lidocaine, may be used for initial mydriasis. For management of intraoperative floppy-iris syndrome, 0.31% may be effective, though a higher concentration (1% to 1.25%) may be required.

Intracameral Drug Delivery: A Review of Agents, Indications, and Outcomes

An intracameral (IC) injection directly delivers the drug into the anterior chamber of the eye. This targeted drug delivery technique overcomes the ocular barriers and offers a high therapeutic concentration of medication at the desired site and consequently better clinical outcomes. IC drug delivery is a safe and effective modality with many advantages over topical delivery. These include excellent bioavailability, reduced systemic risk, and minimal ocular toxicity. Agents delivered via IC injection have shown promising results against infection, inflammation, ocular hypertension, and neovascularization. Current literature shows that IC antibiotics, including cefuroxime, vancomycin, and moxifloxacin, are routinely used for prophylaxis of endophthalmitis. Other drugs available for IC use are steroids, anesthetics, mydriatics, miotics, antivascular endothelial growth factor, antiglaucoma, and alkylating agents. Introduction of sustained-release devices containing dexamethasone or Bimatoprost in anterior chamber via IC route has the potential in treating ocular inflammation and raised intraocular pressure. The complications such as hemorrhagic occlusive retinal vasculitis and toxic anterior segment syndrome have been documented with IC prophylaxis but are rare. In this review, we provide an overview of available IC drugs, their pharmacokinetics, the spectrum of activity, dosage and preparation, prophylactic and therapeutic usage, clinical efficacy, and safety profiles.