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Phenylephrine injection helps control IFIS
The drug dilates the pupil by at least 30% and improves iris muscle tone, a surgeon reports.
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ROME – Intracameral phenylephrine injection minimizes the effects of intraoperative floppy iris syndrome in patients who have taken alpha-1 blocking drugs, according to one surgeon.
“In these patients, the iris floats during irrigation and has a tendency to prolapse to the phaco and side-port incisions while performing surgery,” said Richard B. Packard, MD, at the International Joint Meeting of Ocular Surgery News and the Italian Society of Ophthalmology.
A number of maneuvers have been described to deal with intraoperative floppy iris syndrome (IFIS). The use of iris hooks is, according to Dr. Packard, “time-consuming and can cause damage to the floppy iris.” Other methods use high viscosity viscoelastics such as Healon5 (sodium hyaluronate, Advanced Medical Optics) to dilate the pupil and keep the iris in place. Microincision cataract surgery seems to improve safety in case of IFIS, as irrigation is performed in front of the iris.
“The use of intracameral adrenaline has also been described, but I found that phenylephrine is more effective,” he said.
Phenylephrine counteracts the effects of alpha-1A blockers such as Flomax (tamsulosin, Boehringer-Ingelheim), a drug that is commonly used to treat the urinary symptoms of benign prostatic hypertrophy, he said.
An improved urinary outflow is obtained by the relaxation of the prostate and bladder neck muscles induced by the drug. However, since alpha-1A is the predominant receptor also in the iris dilator muscle, patients treated with tamsulosin progressively lose muscular tone in the iris.
During cataract surgery, the pupils of these patients do not respond to dilation, the iris floats under irrigation and tends to prolapse through the incisions.
Phenylephrine is a sympathomimetic, which stimulates the alpha-receptors in the eye, according to Dr. Packard. It acts on the dilator pupillae, and as this muscle contracts, the pupil dilates. In addition, it gives some tone to the iris muscle fibers, minimizing the tendency of the floppy iris to escape from the eye.
One or more doses
Currently, there is no commercially available phenylephrine-based product for intracameral injection during cataract surgery. Dr. Packard uses Minims (Chauvin Pharmaceuticals), which is a preservative-free 2.5% phenylephrine solution normally used as a pupil dilator.
“On the operating table, the nurse dilutes 7 drops of Minims in 1 mL of saline, and I inject it intracamerally,” he said.
Dr. Packard described his experience with 20 patients with poorly dilated pupils who underwent cataract surgery after prolonged use of alpha-receptor blocking agents. Nineteen were on tamsulosin (Flomax) and one was on zuclopentixol, a treatment for schizophrenia. All patients received preservative-free phenylephrine intracamerally at least once during surgery.
“All responded with a pupil dilation of at least 30%. Fifteen patients required [an additional dose] of phenylephrine during the procedure, because the irrigation of the eye eventually cleared the receptors. None of them required any further surgical maneuver to avoid iris flutter or prolapse, and we had no surgical complications,” Dr. Packard said.
On video, the immediate dilation of the pupil after intracameral injection of phenylephrine was clearly visible. In one patient, after a certain amount of irrigation, the iris started to billow again, and an additional dose of phenylephrine was injected. The dense nucleus was removed without any problem.
“Toward the end of the procedure, after a lot more irrigating, the drug started to wear off again, but it didn’t matter anymore, because the cataract had already been extracted. When we removed the viscoelastic and the iris tried to come out, we were able to keep it under control without any problems,” Dr. Packard said.
One patient had undergone cataract surgery as a child, and had been wearing contact lenses for many years and wanted to have secondary IOL implantation.
“I knew that the capsule was in good order. With intracameral phenylephrine, we managed to double the size of the pupil. Although it was not huge, it was enough to enable us to insert the leading haptic into the eye and to use the elasticity of the pupil to get the rest of the IOL in place,” Dr. Packard said.
“Now, I use phenylephrine in all the cases where the pupil is not the sufficient size. It makes a huge difference in terms of how much and how well the pupil dilates. It’s a simple and safe procedure, and I strongly recommend it,” he said.
For more information:
- Richard B. Packard, MD, can be reached at Arnott Eye Associates, 22A Harley St., London W1G 9BP England; +44-207-580-1074/8792; fax: +44-207-255-1524; e-mail: post@arnotteye.com.
- Michela Cimberle is an OSN Correspondent based in Treviso, Italy, who covers all aspects of ophthalmology. She focuses geographically on Europe.