Pars plana vitrectomy for posteriorly dislocated intraocular lenses: risk factors and surgical approach.

Purpose: To present updated risk factors, anatomical and visual outcomes and a surgical approach to posteriorly dislocated intraocular lenses (IOL).

Methods: A retrospective case series review of patients presenting with posteriorly dislocated IOL to the vitreous was performed. All cases were managed surgically with pars plana vitrectomy (PPV) followed by IOL repositioning and refixation or IOL exchange. Clinical characteristics, risk factors for IOL dislocation, visual outcomes and intraoperative and postoperative complications were investigated.

Results: Forty patients with posteriorly dislocated IOL underwent 3-port PPV and lens retrieval at an average of 6.5 years after cataract surgery. The main causes of IOL dislocation were previous PPV, myopia, pseudoexfoliation syndrome, ocular trauma and recurrent intravitreal injections. The existing IOL was repositioned and secured in 90% of the cases. Visual acuity improved in 34 patients, maintained in 5 and deteriorated in 1. All IOLs were central and stable at final follow-up.

Conclusion: Posterior intraocular lens dislocation is becoming more prevalent. The main underlying causes found in this series were previous vitrectomy, myopia and recurrent intra-vitreal substance injections. Visual acuity improved in most cases after lens repositioning; however visual outcome is often limited due to associated ocular co-morbidities despite adequate lens position. Despite complete lack of zonular support, a posteriorly dislocated IOL can often be preserved by repositioning and fixation of the lens in the posterior chamber. Pathologies primarily associated with this type of lens malposition include history of vitrectomy, high myopia and multiple intravitreal substance injections.