Objective: To investigate the cause and management of posteriorly dislocated lens nucleus in the vitreous cavity during phacoemulsification.
Methods: The authors performed a retrospective study of 18 patients with dislocation of nuclear fragment into vitreous cavity during phacoemulsification at Tong Ren Hospital from August 1994 to January 1999.
Results: 4 cases with dislocated nuclei floated in the anterior vitreous were removed by a lens loop from limbal extensive incision. 2 cases with their dislocated nuclei less than 1/4 of the normal size were under follow-up for 3 - 4 years, and no complications were observed. The final outcome in 1 case with a dislocated nucleus half of its normal size was ocular atrophy as a result of phacoanaphylactic endophthalmitis. 11 cases underwent pars plana vitrectomy. In the operation the nuclei were floated anteriorly by injection of perfluoro-1, 3-dimethylcyclohexane, then they were removed by a lens loop through the limbus and in 2 cases they were fragmented by ultrasound. The main post-operative complication was corneal edema. The final visual acuities generally were improved in varying degrees in 1 month to 4 years of follow-up.
Conclusions: During phacoemulsification, the dislocation of a nucleus is liable to first occur in the peripheral sculpting stage, and secondly in central sculpting stage. A radial tear extending posteriorly from a discontinuous anterior capsulorrhexis is the major risk factor predisposing to posterior dislocation of the nucleus or nuclear fragment. During phacoemulsification, vitrectomy should be performed as soon as possible for a nucleus dislocated into middle or posterior vitreous cavity, and it is a safe and effective method for management of dislocated nucleus.