In phacoemulsification patients, preoperative posterior synechiae, incomplete pupil dilation, pseudoexfoliation and previous vitrectomy appear to be significant risk factors for the displacement of nuclear fragments into the vitreous, according to a prospective, multicenter study.

"The estimated incidence of [displacement of nuclear fragments into the vitreous] during phacoemulsification surgery in the U.K. is two or three per 1,000 operations," the authors said. "Risk factors have been identified that should help to guide case selection for phacoemulsification surgery and modify techniques."

Sajjad Mahmood, BA, MB, BChir, and colleagues evaluated 610 cases of displacement of nuclear fragments into the vitreous and performed a case-control analysis of 521 patients who underwent uncomplicated phaco to determine the epidemiology and risk factors contributing to the displacement. All cases were reviewed between March 2003 and March 2004 using the British Ophthalmological Surveillance Unit.

The estimated incidence of displacement of nuclear fragments into the vitreous was between 0.19% and 0.28%, the authors noted.

Patients in the fragment displacement group averaged 76.8 years of age, significantly older than the patients in the control group, who averaged 74.3 year of age (P < .001).

Preoperative risk factors in the fragment displacement group included posterior synechiae (5.1%), incomplete pupil dilation (59.5%), pseudoexfoliation (5.6%) and previous vitrectomy (7.8%). In the control group, only 2.2% of patients had posterior synechiae, 8.8% had incomplete pupil dilation, 1.4% had pseudoexfoliation and 2.2% had previous vitrectomy, according to the study.

Among patients in the fragment displacement group and the control group, significant operative variables related to surgical experience were topical anesthesia (14.3% vs. 3.1%), sub-Tenon's anesthesia (51.4% vs. 37.2%) and the necessity for trypan blue ophthalmic solution (13.7% vs. 2.4%), respectively, according to the study, published in the April issue of British Journal of Ophthalmology.