Abdullah A. Cheema, MBBS BSc¹

Babar A. Khan,  FRCS²

¹Imperial College London
School of Medicine
United Kingdom

²Department of Ophthalmology
North Road Eye Clinic
Bronglais Hospital
Aberystwyth

Abstract:

We describe use of 0.5% intracameral preservative free pilocarpine during cataract and glaucoma surgery for pupillary miosis, as alternative to commonly used intraoperative intracameral miotic agents such as acetyl choline and carbachol. This agent is safe and effective in achieving intraoperative miosis and free of corneal toxicity and causing intraocular inflammation.

Introduction

Intracameral miotic agents, such as acetyl choline and carbachol , are commonly used during ocular surgery for pupillary miosis. This is desirable in certain steps of cataract and glaucoma surgery, such as to prevent iris incarceration, achieve regular pupil after anterior vitrectomy , prevent peripheral anterior synechia, stabilization of intraocular lens and prevent capture of Intraocular lens implant in the anterior chamber.

The commonly used intracameral miotic agents, such as acetyl choline and carbachol, have a proven record of safety, non-toxicity to ocular tissues and corneal endothelium. However, these agents are expensive, and recently there have been issues with availability due to manufacturing issues.

Pilocarpine, a parasympathomimetic miotic agent, has long been used as topical medication for glaucoma. This agent is freely and easily available and is very inexpensive. However, its use as intracameral agent for pupillary miosis has not been fully documented. In this short report we share our experience of using intracameral preservative free pilocarpine during cataract and glaucoma surgery for pupillary misois.

Subjects, Methods and Results

Five patients undergoing combined phaco-trabeculectomy and solo trabeculectomy surgery over a period of two weeks were enrolled in the study. Two patients underwent combined cataract and trabeculectomy procedure, while three patients who were phakic underwent trabeculectomy procedure.

0.5 ml of preservative free sterile 2% pilocarpine (minims. Bosch and Lomb) were added to 1.5 ml of balanced salt solution (BSS) The BSS was drawn from adrenaline free bottle. This roughly achieved a concentration of 0.5% pilocarpine for intracameral use. The anterior chamber was irrigated with reconstituted pilocarpine. The amount of fluid injected into anterior chamber depended upon observed response to miotic drug. No more than 2 ml intracameral pilocarpine was irrigated into the anterior chamber.

A good degree of miosis was observed in all patient within few seconds to few minutes of intracameral administration of pilocarpine during surgery. The response in phakic trabeculectomy patients was prompt, as compared to patients undergoing combined phacoemulsification and trabeculectomy procedure. The patients were reviewed on the first day, one week and one month post operatively. None of the patients showed any evidence of corneal toxicity or corneal oedema at any of the post operative visits. There was no evidence of intraocular inflammation and intraocular pressures were not elevated.

Discussion

Pilocarpine is cheap and readily available miotic agent in eye clinics and ophthalmic operating rooms. The use of pilocarpine as intracameral agent has not been documented extensively. There can be concerns about corneal toxicity of the drug.

High dosage of pilocarpine can be toxic to corneal endothelium. Coles has shown that pilocarpine above 2.5mg/ml can be toxic to corneal endothelium. Wutthiphan et al reported use of intracameral pilocarpine in concentration of 0.13mg/ml without any ill effects or corneal toxicity (1). Arora reported similar results with use of 0.5% intracameral pilocarpine (2). We noted quick miosis of pupil in phakic patients undergoing trabeculectomy, while it took few minutes for miosis to occur in patients with combined phaco-trabeculectomy. This could be due to presence of OVD in the anterior chamber which allowed slow dispersion of drug to ocular tissues.

In conclusion, we found that 0.5 % intracameral preservative free pilocarpine is safe and effective for intraoperative miosis. We did not find any evidence of corneal toxicity, and use of preservative free pilocarpine may also contribute to lack of corneal toxicity of the drug. It is cheap and its ready availability in sterile minims form makes its very easy for reconstitution and quick use.

References

1. Wutthiphan S, Hanutsaha P, Jenchitr W. Intracameral pilocarpine in topical phacoemulsification. J Med Assoc Thai. 2000 Dec;83(12):1452-7. PMID: 11253883.
2. Arora A. To evaluate the effect of 0.5% intracameral pilocarpine on intraocular pressure after topical phacoemulsification. IOSR Journal of Dental and Medical Sciences (IOSR-JDMS). 2018;17(3):59-61. https://europub.co.uk/articles/-A-369065