Effect of intracameral injection of bisulfite-containing phenylephrine on rabbit corneal endothelium

Efficacy and Safety of an Intracameral Combination of Two Mydriatics and an Anesthetic for Phacoemulsification in Complicated Patients

Background:

Advantages of intracameral mydriatics have been demonstrated in healthy patients, but safety and efficacy in complicated subjects remain to be assessed.

Objective:

The purpose of this study is to evaluate efficacy and safety of an intracameral combination of phenylephrine (0.31%), tropicamide (0.02%) and lidocaine (1%) (Mydrane®, Thea Inc.) in phacoemulsification surgery in subgroups of patients affected by different systemic and ocular diseases.

Methods:

125 patients were recruited and compared with a control group of 39 patients. Both groups have been divided according to the presence/absence of ocular or systemic diseases. In course of surgery, grade of mydriasis and ocular analgesia have been evaluated by the surgeon. During follow-up, eventual adverse events have been monitored. Also, comfort reported by patients and surgeon has been investigated.

Results:

99.2% of patients receiving the intracameral formulation achieved acceptable mydriasis (> 6 mm), maintained during capsulorhexis, phacoemulsification and IOL insertion without the need of additional mydriatics. No adverse events or sings of unsuccessful surgery were observed among treated patients.

Conclusion:

An intracameral mydriatic solution can be a safe and comfortable tool for inducing and maintaining intraoperative mydriasis and analgesia, even in complicated patients.

Assessing the accuracy of intracameral phenylephrine preparation in cataract surgery

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.

Patient considerations in cataract surgery - the role of combined therapy using phenylephrine and ketorolac

Cataract, a degradation of the optical quality of the crystalline lens, progressive and age-related, is the leading cause of treatable blindness worldwide. Cataract surgery is the most common surgical procedure performed by ophthalmologists and is the only effective treatment for cataracts. Advances in the surgical techniques and better postoperative visual outcomes have progressively changed the primary concern of cataract surgery to become a procedure refined to yield the best possible refractive results. Sufficient mydriasis during cataract removal is critical to a successful surgical outcome. Poor pupil dilation can lead to serious sight-threatening complications that significantly increase the cost of surgery and decrease patients comfort. Mydriasis is obtained using anticholinergic and sympathomimetic drugs. Phenylephrine, an α1-adrenergic receptor agonist, can efficiently dilate the pupil when administered by intracameral injection. Additionally, nonsteroidal anti-inflammatory drugs (NSAIDs) like ketorolac, which inhibit the synthesis of prostaglandins, are used to decrease intraoperative miosis, control pain and inflammation associated with cataract surgery, and to prevent the development of cystoid macular edema following surgery. Recently, a new combination of phenylephrine and ketorolac (Omidria^®) has been approved by United States Food and Drug Administration for use during cataract surgery to maintain intraoperative mydriasis, prevent miosis, and reduce postoperative pain and inflammation. Clinical trials have shown that this new combination is effective, combining the positive effects of both drugs with a good safety profile and patient tolerability. Moreover, recent reports suggest that this combination is also effective in patients with high risk of poor pupil dilation. In conclusion, cataract is a global problem that significantly affects patients' quality of life. However, they can be managed with a safe and minimally invasive surgery. Advances in surgical techniques and newer pharmacological agents such as the combination of phenylephrine and ketorolac, together with better intraocular lenses, have greatly improved visual outcomes and thus patients' expectations regarding visual recovery are also increasing.