Posterior capsule tears
Precautions may avoid tears, but be prepared to manage them.
Capsulorhexis tears and posterior capsule breaks can be minimised using good surgical technique and precautions in high-risk patients. When they do occur, however, surgeons should be prepared to manage them, presenters told the ASCRS ASOA 2019 Annual Meeting in San Diego, USA.
Recent literature puts the overall rate of posterior capsule breaks at about 3.2%, though some large series show rates below 1.0%, said Thomas Kohnen MD, PhD, professor and chair of the department of ophthalmology at Goethe University, Frankfurt, Germany. That’s down from 8.4% from the can-opener capsulotomy era and 4.8% in the early years of capsulorhexis.
And while some surgeons use femtosecond lasers to reduce posterior breaks, recent studies show no differences overall between laser-assisted and manual cataract procedures done by experienced surgeons.
Occasionally, posterior capsule breaks are associated with the cataract itself, as with primary holes from posterior polar cataracts, Prof Kohnen noted. Other risk factors include male gender, pseudoexfoliation, diabetes and renal failure, so surgeons should take precautions with these patients. Most often, though, posterior capsule breaks are caused by surgery, and may occur at any point in surgery, including during lens removal, cortex aspiration and intraocular lens (IOL) implantation, he added.
Avoiding and recovering
from radial tears
Posterior ruptures are often preceded by radial tears during capsulorhexis, Prof Kohnen said. These can be minimised by starting the capsulorhexis toward the centre of the anterior capsule and tearing outward in a spiral that intersects itself at the desired diameter. Should a radial tear begin, the capsulotomy may be recovered by picking it up from outside the tear and bringing it back toward the centre, rather than trying to continue the tear from the inside out.
Understanding why radial tears occur is important to managing them, said Richard Tipperman MD, of Wills Eye Hospital, Philadelphia, USA. Causes include difficulty initiating the tear, poor visualisation due to white cataracts, small pupils, young patients and calcified capsules, each requiring its own approach.
Flat anterior chambers can create abnormal vector forces that push tears in unpredictable directions, as do forceps with tips that don’t quite line up. Dr Tipperman advised taking the time to get a pair of good forceps rather than pushing through and try to manage.
“The road to ruin is paved with good intentions,” he said.
In the event of radial tears, Dr Tipperman also advised releasing the capsule and repositioning the forceps to tear centrally. If the tear extends past the iris, he recommends using hooks to get a better view, which may allow completion of a circular capsulotomy.
When the tear cannot be recovered, converting to a can-opener capsulotomy is an option, Dr Tipperman said.
“Remember, these were done for years with excellent results.”
However, a can-opener capsulotomy is at risk for additional radial tears, so the lens should be prolapsed out of the bag before phacoemulsification, if possible.
The can-opener also may render the capsule unsuitable for in-the-bag lenses, so sulcus fixation of a three-piece lens may be necessary.
Managing posterior breaks
Capsule ruptures during lens removal are potentially disastrous, Prof Kohnen said.
“The biggest goal is to keep the nucleus from diving into the vitreous.” This can be done by deepening the irrigation bottle to increase pressure, applying viscoelastic in front of and behind the core to avoid lens posterior dislocation and protect the endothelium during lens removal. Should the lens drop into the vitreous, pars plana vitrectomy likely will be required to remove it.
“It’s not a good idea to try to remove it from the anterior,” Prof Kohnen cautioned.
For tears during cortex aspiration the question is whether the vitreous membrane is intact. If so, the tear should be extended into a round opening to prevent the radial tear from extending further to the periphery, which may make it impossible to implant a lens in the bag, Prof Kohnen said. Any vitreous entering the anterior segment must be removed using anterior vitrectomy.
Posterior tears during lens implantation may be recovered with the lens implanted in the bag if there is enough residual capsule to support it, Prof Kohnen said. This involves carefully removing any vitreous behind the lens.
How an IOL should be implanted after a capsule rupture depends on the condition of the capsular bag, Prof Kohnen added. It may be possible to place a lens in a bag with a posterior tear if there is enough support. If the rhexis is not torn, an optic capture in the capsulorhexis with haptics in the sulcus may be possible.
If the bag will not support a lens, a sulcus placement may be necessary, Prof Kohnen advised. Avoid placing single-piece IOLs in the sulcus to avoid future iris chafe and pigment dispersion, which may lead to glaucoma.
In cases of lost zonules, open the sulcus ciliaris with viscoelastic, retract the iris and position haptics away from the foramen in case of rhexis rupture, he advised.
Thomas Kohnen: Kohnen@em.uni-frankfurt.de