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Editor,—According to a national sample survey of the disabled in 1987, cataract was the primary cause of blindness in China.1 Since manipulations such as retrobulbar injection, ocular compression, and traction of the extraocular muscle were involved in cataract surgery, oculocardiac reflex could not be avoided theoretically. We have conducted a study to determine the incidence of the reflex in cataract surgery in the elderly.
Thirty patients over the age of 60 were involved. At least 60 seconds of dynamic electrocardiogram was recorded with a 24 hour Holter’s monitor at each of the following steps: preoperation, retrobulbar anaesthesia, softening of the eyeball, superior rectus suture, corneoscleral incision, delivering the nucleus, and posterior chamber lens implantation. Oculocardiac reflex was defined as at least a 10% decrease in heart rate below relative baseline; that means electrocardiac activities after the beginning of each procedure were compared with those in the previous one, so as to judge more precisely influences of different procedures on electrocardiac activities.
Of the 30 patients included, 10 patients (33.3%) were noted to have 14 oculocardiac reflexes in all. Among them, six patients had abnormal preoperative electrocardiograms. An oculocardiac reflex was caused by softening of eyeball in five (35.7%) patients, retrobulbar anaesthesia in four (28.6%) patients, delivering the nucleus and intraocular lens implantation in two patients, and corneoscleral incision in one patient. The most significant drop in heart rate was 33 beats per minute from baseline. Three patients had more than one oculocardiac reflex during the operation. In addition, arrhythmia was noted in five (16.7%) patients and only two of them suffered oculocardiac reflex.
Our results indicate that most steps in cataract extraction procedure may elicit the oculocardiac reflex. Fortunately, the reflex encountered in our study is generally brief, resulting in no symptoms or any other sequelae. However, the reflex is potentially fatal and can cause cardiac arrest and even death.23 As 64.3% (9/14) of the reflexes occurred at the time of retrobulbar anaesthesia and softening of eyeball, more attention should be paid when these procedures are performed. Surgeons who perform the operation should inform patients of this possibility, especially for aged people with severe heart disease.
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