The posterior dislocation of lens fragments is an infrequent but well-known complication of cataract surgery.1-5 Its incidence (reported at between 0.3% to 1.0%)5,6 is higher with phacoemulsification than with extracapsular cataract surgery. The complication can be stressful to the surgeon, and it may result in significant inconvenience to and prolonged recovery for the patient. Additional surgery such as pars plana vitrectomy is frequently necessary. Retained lens fragments may lead to sight-threatening problems such as chronic uveitis, corneal edema, cystoid macular edema, increased IOP, and retinal detachment. Appropriate management, however, can minimize secondary complications and achieve a good visual prognosis in a majority of patients.

RISK FACTORS

The risk factors for dislocated lenticular material include the presence of a hard nucleus, a miotic pupil with difficult visualization, weakened zonules (due to pseudoexfoliation, Marfan's syndrome, or previous trauma), deep-set eyes, traumatic cataract, previous vitrectomy, the patient's movement during surgery, and the surgeon's inexperience with the phaco technique.5 Capsular rupture, zonular dehiscence, and the posterior dislocation of lenticular fragments most commonly occur during emulsification of the lens and cortical clean-up. Preventing and recognizing capsular tears during these steps of cataract surgery are therefore paramount.

PREOPERATIVE MANAGEMENT

Patients usually expect an excellent visual outcome after cataract surgery. Informed consent that includes a discussion of the risk of dislocated lens material is important, not just for medicolegal reasons, but also because it may reduce pressure on the cataract surgeon to solve the problem during cataract surgery, an effort that may actually be counterproductive.

INTRAOPERATIVE MANAGEMENT

Most important is to minimize attempts at retrieving intravitreal lens fragments in order to avoid traction on the vitreous. Aggressive efforts at retrieval anteriorly without concomitant posterior vitrectomy can result in giant retinal tears and retinal detachments.7-9 One should avoid irrigating posteriorly dislocated fragments into the pupillary space. Various techniques such as posterior-assisted levitation via the pars plana have been described, but they should be performed judiciously.10,11

One should minimize further extension of the capsular tear as well as forward movement of the vitreous. In the absence of anteriorly displaced vitreous, one may inject viscoelastic material into the anterior chamber to prevent further anterior migration of the vitreous. Inserting a second instrument behind the lens fragment can prevent posterior migration. Some have reported using a Sheet's glide to act as a barrier to aid with emulsification of residual lens material in the anterior chamber.12 Other options include converting to extracapsular cataract extraction or removing lenticular material using toothed lens-fragment forceps.

If anterior migration of the vitreous has occurred, the surgeon should perform a careful and thorough anterior vitrectomy prior to removing the retained lens material. One should also pay attention to any cortical material that may have migrated into the anterior chamber and into the angle, because it can also cause significant postoperative inflammation.

It is important that the surgeon remain calm and resist the urge to chase after the dropped lens material. Instead, one should remove only the fragments that are readily retrievable and perform a thorough anterior vitrectomy as needed.

A PCIOL is an option if a sufficient amount of lens capsule remains. Otherwise, one may consider inserting an ACIOL or leaving the eye aphakic for future management with a sutured PCIOL or an ACIOL. A comparison of various IOL placements revealed no significant difference in patients' final visual outcomes.1 It is acceptable to leave the patient aphakic if a rock-hard nucleus dislocates posteriorly; such cases may require the retina surgeon to deliver the lens fragment through a limbal incision, if fragmentation proves difficult. In the rare instance of a PCIOL's posterior dislocation during management, the surgeon should avoid inserting another IOL until a retina specialist has removed the first one.

Silicone IOLs should be avoided in eyes with dislocated lens fragments, because some patients may need posterior-segment surgery and possible repair of a retinal detachment, requiring air-fluid exchange or the use of silicone-oil tamponade. Moisture tends to condense on IOLs made of silicone during air-fluid exchange and reduce visualization during the posterior-segment surgery. Silicone oil may become irreversibly adherent to silicone IOLs and may necessitate the IOL's eventual removal.

It is wise to place a suture at the site of the corneal incision. Attempts to retrieve lenticular fragments may have violated the integrity of the wound's construction, and it may no longer be watertight, which will increase the risk of wound leak, hypotony, choroidal hemorrhage, and endophthalmitis. Furthermore, watertight incisions are easier to manage during work in the posterior segment.

POSTOPERATIVE MANAGEMENT
Inflammation

Frequent topical corticosteroids and cycloplegic agents should control postoperative inflammation. An antiglaucoma medication may be necessary, because more than one-half of these eyes may have elevated IOP prior to vitrectomy.2-5,13 The surgeon should closely monitor corneal edema, high IOP, and the development of cystoid macular edema. In addition, one should keep in mind that, in rare instances, severe postoperative inflammation may be due to concomitant endophthalmitis, which should be detected and treated as soon as possible.14

The Timing of Vitrectomy

A 1994 survey of anterior segment surgeons found that they refer 77% of cases of retained lens fragments to vitreoretinal surgeons and manage 23% themselves.6 If the retained lens fragment is small, it may be resorbed over time without surgical intervention. A prospective nonrandomized study by Rossetti and Doro, however, found that vitrectomy can yield faster visual rehabilitation and a better quality of vision when compared to nonvitrectomized eyes, but the procedure poses a risk of retinal detachment.15 Cataract surgeons should obtain a retinal consultation as soon as possible in cases with a large fragment dropped posteriorly, poor visualization of the fundus, retinal detachment, significant inflammation, vitreous hemorrhage, or elevated IOP.

The optimal timing of vitrectomy for the removal of lenticular material has not been firmly established. Although larger studies did not show an association between the timing of vitrectomy and visual outcome, smaller studies have suggested a trend toward less inflammation and a possibly improved visual outcome with earlier vitrectomy.1,13,16-18

Vitrectomy may be performed on the same day, if a retina surgeon is readily available, in order to avoid a second surgery. Because same-day surgery is not possible in most settings and the best timing of surgery is undecided, the cataract surgeon should consider staged management.

Initial aggressive pharmacological therapy and delayed vitrectomy may permit time to improve corneal edema and acute postoperative inflammation as well as visualization during pars plana vitrectomy. Nevertheless, it would be prudent to seek a retinal consult early in order to rule out retinal tears and detachments and to manage secondary complications in a timely manner. In general, pars plana vitrectomy may be performed within 1 to 3 weeks, if there are no other significant secondary complications.

Visual Outcome

Excellent visual outcomes are possible for patients undergoing vitrectomy for retained lens fragments. In most reports, over one-half of patients achieved a final visual acuity of 20/40 or better.1-5,19-21

The causes of a poor visual outcome include cystoid macular edema, preexisting ocular disease, corneal edema and decompensation, retinal detachment (both before and after vitrectomy), and an epiretinal membrane.20,21 In a series by Moore et al that included 343 patients, retinal detachment was observed prior to vitrectomy in 7.3% and occurred after vitrectomy in 5.5%, with an overall rate of 12.8%.8 Complicated detachments with giant retinal tears occurred as well. Only 18% of the eyes with retinal detachment achieved a visual acuity of 20/40 or better. Poor visual acuity prior to pars plana vitrectomy and the presence of a retinal tear at the time of vitrectomy were associated with a higher rate of subsequent retinal detachment.8,9

Because the risk of retinal tears and detachment is correlated with vitreous manipulation, both during cataract surgery and pars plana vitrectomy, cataract and retina surgeons should minimize vitreous traction as much as possible. They should thoroughly inspect the peripheral retina in these patients. Long-term follow-up is recommended in eyes that had retained lens fragments in order to detect and manage the delayed onset of complications such as cystoid macular edema, epiretinal membrane, or retinal detachment.21

In summary, the dislocation of lenticular material into the vitreous cavity during cataract surgery is a rare but potentially serious, sight-threatening complication. Pars plana vitrectomy is effective for removing retained lens fragments, lowering the IOP, and reducing inflammation. Ophthalmologists must take every care to reduce the possibility of retinal detachment, which is a major cause of poor visual outcomes. The majority of patients with retained lens fragments have a good visual prognosis, when the cataract and retina surgeons work as a team to minimize secondary complications through the appropriate and timely management of the case. 

Dennis P. Han, MD, is Jack A. and Elaine D. Klieger Professor of Ophthalmology at the Medical College of Wisconsin in Milwaukee. Dr. Han may be reached at (414) 456-7875; dhan@mcw.edu.
Judy E. Kim, MD, is Associate Professor of Ophthalmology at the Medical College of Wisconsin in Milwaukee. Dr. Kim may be reached at (414) 456-7875; judykim@mcw.edu.

1. Kim JE, Flynn HW Jr, Smiddy WE, et al. Retained lens fragments after phacoemulsification. Ophthalmology. 1994;101:1827-1832.
2. Bourne MJ, Tasman W, Regillo C, et al. Outcomes of vitrectomy for retained lens fragments. Ophthalmology. 1996;103:971-976.
3. Margherio RR, Margherio AR, Pendergast SD, et al. Vitrectomy for retained lens fragments after phacoemulsification. Ophthalmology. 1997;104:1426-1432.
4. Hansson LJ, Larsson J. Vitrectomy for retained lens fragments in the vitreous after phacoemulsification. J Cataract Refract Surg. 2002;28:1007-1011.
5. Monshizadeh R, Samiy N, Haimovici R. Management of retained intravitreal lens fragments after cataract surgery. Surv Ophthalmol. 1999;43:397-404.
6. Leaming DV. Practice styles and preferences of ASCRS members—1994 survey. J Cataract Refract Surg. 1995;21:378-385.
7. Olsson RB, Ritland JS, Bjornsson OM, et al. A retrospective study of patients with retained nuclear fragments after cataract extraction. Acta Ophthalmol Scand. 200;78:677-679.
8. Moore JK, Scott IU, Flynn HW Jr, et al. Retinal detachment in eyes undergoing pars plana vitrectomy for removal of retained lens fragments. Ophthalmology. 2003;110:709-713.
9. Smiddy WE, Guererro JL, Pinto R, Feuer W. Retinal detachment rate after vitrectomy for retained lens material after phacoemulsification. Am J Ophthalmol. 2003;135:183-187.
10. Chang DF, Packard RB. Posterior assisted levitation for nucleus retrieval using Viscoat after posterior capsule rupture. J Cataract Refract Surg. 2003;29:1860-1865.
11. Lifshitz T, Levy J. Posterior assisted levitation: long-term follow-up data. J Cataract Refract Surg. 2005;31:499-502.
12. Frankel J. Managing retained intravitreal lens fragments after cataract surgery. Surv Ophthalmol. 2000;44:363-364.
13. Yeo LMW, Charteris DG, Bunce C, et al. Retained intravitreal lens fragments after phacoemulsification: a clinicopathological correlation. Br J Ophthalmol. 1999;83:1135-1138.
14. Kim JE, Flynn HW Jr, Rubsamen PE, et al. Endophthalmitis in patients with retained lens fragments after phacoemulsification. Ophthalmology. 1996;103:575-578.
15. Rossetti A, Doro D. Retained intravitreal lens fragments after phacoemulsification: complications and visual outcome in vitrectomized and nonvitrectomized eyes. J Cataract Refract Surg. 2002;28:310-315.
16. Wilkinson CP, Green WR. Vitrectomy for retained lens material after cataract extraction. The relationship between histopathologic findings and the time of vitreous surgery. Ophthalmology. 2001;108:1633-1637.
17. Kageyama T, Ayaki M, Ogasawara M, et al. Results of vitrectomy performed at the time of phacoemulsification complicated by intravitreal lens fragments. Br J Ophthalmol. 2001;85:1038-1040.
18. Stefaniotou M, Aspiotis M, Pappa C, et al. Timing of dislocated nuclear fragment management after cataract surgery. J Cataract Refract Surg. 2003;29:1985-1988.
19. Vilar NF, Flynn HW Jr, Smiddy WE, et al. Removal of retained lens fragments after phacoemulsification reverses secondary glaucoma and restores visual acuity. Ophthalmology. 1997;104:787-792.
20. Scott IU, Flynn HW Jr, Smiddy WE, et al. Clinical features and outcomes of pars plana vitrectomy in patients with retained lens fragments. Ophthalmology. 2003;110:567-572.
21. Greven C, Piccione K. Delayed visual loss after pars plana vitrectomy for retained lens fragments. Retina. 2004;24:363-367.