August 2018

CATARACT

Presentation spotlight
The dropping and dropped nucleus


by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer

“The key is early intervention, especially if there is raised IOP or uveitis. We can prevent sequelae with prompt surgery and achieve nearly normal outcomes.”
—Paul Rosen, MD

A cataract expert gives best course of action in cataract cases involving a torn posterior capsule

Managing complicated cataract surgery that involves a dropping or dropped nucleus requires experience. According to Paul Rosen, MD, Oxford Eye Hospital, Oxford, U.K., who spoke on the topic at the 22nd ESCRS Winter Meeting, these unwanted events happen to both highly practiced and less practiced cataract surgeons with an incidence of 0.18%. Knowing how to handle the situation in the moment is key, he said. “You need a planned treatment pathway,” Dr. Rosen noted. “Primary management involves an anterior vitrectomy, without IOL implantation. Secondary management should happen within 3 weeks, but best within 10 days, and include a vitrectomy, nucleus removal, and IOL implantation. The key is early intervention, especially if there is raised IOP or uveitis. We can prevent sequelae with prompt surgery and achieve nearly normal outcomes.”

How does the nucleus drop?

A dropping or dropped nucleus has a number of etiologies, including an anterior capsule rim tear that can extend posteriorly to become a posterior tear, a posterior capsule tear that can occur during phaco, and zonular disinsertion.
Posterior capsule tears are associated with a number of telltale signs that indicate something is wrong, such as a deepening anterior chamber, an unstable lens, pupil contour changes like dilation or an irregular shape caused by vitreous coming through the wound, and when the phaco appears to stop working or vibrates.

Management of events during phaco

When the posterior capsule is torn during phaco, the surgeon needs to stop and observe the nucleus. What the surgeon does next depends on the position of the nucleus, whether it is dropping or has dropped into the vitreous. “If the nucleus is anterior enough to enable the surgeon to stabilize it, clear the vitreous from the anterior chamber, then consider how to remove the nucleus,” he explained. “Options to remove the nucleus are phaco, convert to extracapsular cataract extraction (ECCE), or letting the nucleus drop and thereby causing as little damage as possible and referring the patient to a vitreoretinal surgeon.”
According to Dr. Rosen, the technique of posterior assisted levitation (PAL) is somewhat controversial. It involves inserting a needle 2.5 mm behind the limbus via the pars plana into the posterior chamber and injecting OVD behind the lens to support the lens and prevent it from falling. This method provides a cushion that keeps it from dropping any deeper. “Some people say PAL is a bad choice because it will cause vitreous traction and potentially risk retinal detachment,” he said. “I think it is useful if you don’t have immediate access to a vitreoretinal surgeon. Its use depends on a facility’s availability for secondary repair, risk of vitreous base/retinal damage, or if the surgeon prefers to allow the nucleus to drop and plan a secondary procedure. PAL raises the lens material and lets the surgeon retrieve it via the anterior chamber.”

Management of events if the nucleus has dropped

Once the nucleus has dropped, it is a different scenario. Management begins with clearing any vitreous, demarcated with triamcinolone, from the anterior chamber. The surgeon needs to manage postoperative inflammation and IOP rise. A referral to a vitreoretinal surgeon should be done for a pars plana vitrectomy. “What you never do is put the phaco probe into the vitreous cavity or even the anterior chamber when vitreous is present to try and remove the fragments of nucleus because you will cause vitreoretinal traction and potentially a retinal tear/detachment, Dr. Rosen said. “Also, you should not put an infusion fluid into the vitreous cavity in an attempt to flush the fragments out into the anterior chamber. Doing this will risk producing a retinal tear and detachment.”
The potential problems of a dropped nucleus include corneal failure, uveitis, vitritis, glaucoma, cystoid macular edema, retinal detachment, and endophthalmitis. Before nucleus removal, the surgeon must check IOP and uveitis. The corneal edema should be allowed to clear and dexamethasone taken every 1–2 hours. Surgery to remove the nuclear fragments should be performed within 3 weeks, although Dr. Rosen aims for surgery within 10 days, then considers a secondary IOL.
A study on individuals with retained lens fragments who had pars plana vitrectomy showed that earlier surgery results in better visual outcomes. The median interval between cataract surgery and PPV was 12 days. Visual acuity was >20/40 in 29 (9%) patients preoperatively and in 190 (56%) at last follow-up (P<0.001). Visual acuity was <20/200 in 224 patients (66%) preoperatively and in 67 (20%) at last follow-up (P<0.001).1
A second, unrelated clinical trial corroborated these findings for visual recovery as well as the postoperative risk of uveitis, IOP rise, and retinal detachment. In the study’s late vitrectomy group, 66.6% of eyes developed persistent uveitis, 53.3% of eyes showed elevated IOP, and five eyes had retinal detachment. In the early PPV group, 16.6% developed uveitis and 20% showed elevated IOP, with only one eye having retinal detachment. The final visual acuity was 20±50 in early PPV and 20±200 in late PPV group.2

Should a lens be implanted as a primary procedure?

IOL implantation has to be carefully considered. Dr. Rosen said, “My view about primary IOL implantation is that you need 240 degrees of capsule, at least, to support a three-piece IOL, otherwise you need to consider using an iris supported or anterior chamber IOL. If there is a significant amount of lens material in the vitreous cavity, and a vitrectomy is likely, a lens implant should not be inserted.

References

1. Scott IU, et al. Clinical features and outcomes of pars plana vitrectomy in patients with retained lens fragments. Ophthalmology. 2003;110:1567–72.
2. Salehi A, et al. Visual outcome of early and late pars plana vitrectomy in patients with dropped nucleus during phacoemulsification. J Res Med Sci. 2011;16:1422–9.

Editors’ note: Dr. Rosen has no financial interests related to this article.

Contact information

Rosen
: phrosen@rocketmail.com

The dropping and dropped nucleus The dropping and dropped nucleus
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