Take-Home Message: A calcium channel blocker may be associated with marginal pupil dilation, making it more likely that pupil-dilating devices will be needed during phacoemulsification.
Danbury, CT—Instillation of a calcium channel blocker, amlodipine (Norvasc, Pfizer), into the eye may complicate phacoemulsification by causing marginal dilation of the pupil.
In such cases, pupil-dilating devices may facilitate cataract removal, said Matthew D. Paul, MD, who is in private practice in Danbury, CT.
Ophthalmologists will recall how a decade ago, David Chang, MD, and John Campbell, MD, reported the condition referred to as intraoperative floppy iris syndrome and its relationship to a treatment in men for symptoms of an enlarged prostate, tamsulosin (Flomax, Boehringer Ingelheim Pharmaceuticals). The resultant iris prolapse at first was controlled intraoperatively using iris hooks, bimanual techniques, and intracameral epinephrine and later, by intraocular iris-dilating rings or specula.
Dr. Paul and his colleague, Samuel Zuckerman, conducted a study in which they retrospectively reviewed the results of one surgeon for the use of a pupil-dilating ring in cases in which tamsulosin was not used. The investigators identified a group of patients with borderline pupil dilation.
“Our study suggested that amlodipine alters pupil dilation and reaction to dilating drugs, although not to the same pathologic nature as tamsulosin—yet, significantly enough to push surgeons to use iris-dilating rings,” he said.
“We felt that for these patients it was advantageous, safer, and in the patients’ best interests to use these iris-dilating devices to enlarge the pupil and facilitate phacoemulsification,” he said. “Generally, these patients have pupils between 2 and 4 mm who failed aggressive regimens of preoperative dilation.”
Cases needing dilating devices
Of 100 patients identified, 89 patients had no history of tamsulosin use. An iris-dilating device (Malyugin Ring, MicroSurgical Technology) was needed in 15 of these patients. The average age of the patients in whom the ring was used was 81.3 years compared with an average age of 73.3 years in patients in whom the ring was not used.