A wide range of technologies can impact outcomes in young ophthalmic patients.
This article was reviewed by Ken K. Nischal, MD, MBBS, FRCOphth
New devices for use in pediatric surgeries are making challenging procedures less so. Ken K. Nischal, MD, MBBS, FRCOphth, described how he benefits from use of the bag-in-the-lens (BIL), precision pulse capsulotomy, and integrated intraoperative optical coherence tomography (OCT) in children, whose tissues react differently from those of adults.
According to Dr. Nischal, the new technologies can positively impact the surgical outcomes in these patients.
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This innovation, developed by Mary Jose Tassignon, MD, and colleagues in 2005 (Verh K Acad Geneeskd Belg 2005;67:277-88), involves creation of one opening of the same size in both the anterior and posterior capsules. A lens that is grooved fits by placement of two leaves into the groove.
“This results in sequestration of the lens epithelial cells and thus elimination of opacification in the visual axis,” according to Dr. Nischal, division chief and professor ophthalmology, University of Pittsburgh and Children’s Hospital of Pittsburgh of the University of Pennsylvania Medical Center, Pittsburgh.
Dr. Tassignon developed foldable rings to ensure creation of a precise capsulotomy. The rings are placed on the capsule and covered with a viscoelastic agent and serve as a template to create the opening.
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“If surgeons are having difficulties doing pediatric cataract surgeries, the rings can be used to get the correct sizing of the opening,” Dr. Nischal said. “Even though a child’s capsule is elastic, this works.”
A posterior capsulorhexis is created using the anterior opening as the template. He explained that in a 4-year-old child. The lens appeared the same two years postoperatively as it did on the first day postoperatively, with a perfectly clear visual axis.
There is a learning curve attached to this procedure, in that it can be difficult to get the two capsules anchored into the groove, Dr. Nischal noted.
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Precision pulse capsulotomy
Capsulotomies are always challenging, so simplification of the process is desirable. Ramesh Kekunnaya, MD, and colleagues developed a technique to automate capsulotomies in pediatric patients to remove the guesswork that is associated with the manual procedure (BMJ Open Ophthalmol 2019;4:e000255. doi:10.1136/ bmjophth-2018-000255).
Dr. Nischal explained that the technique uses a fine alloy that is extremely flexible and, in this procedure, is placed in a hood of silicone. The hood opens and applies suction to the capsule. Nanopulses of electricity travel along the alloy and vaporize the water between the alloy and the capsule to create a 360º simultaneous capsulotomy, Dr. Nischal described.
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After the lens material is removed, an opening left is slightly larger than it was originally.
“This technology may become useful if it can be made to a small size for use with children,” he said.
OCT for pediatric cataract
Dr. Nischal believes integrated intraoperative OCT is helpful for planning and teaching and is especially helpful in complex cases. A benefit is that while looking through the microscope, the surgeon can see the OCT image and the surgical image in one ocular. He explained how he uses this technology in a number of different clinical scenarios.
While performing all of his pediatric cases, Dr. Nischal first removes the peripheral soft lens material, which differs to the approach in adult surgeries, and removes the nuclear material last.
“At this stage, if vitreous emerges, it can be tamponaded; remember congenital defects in the posterior capsule are much more common in children with cataracts,” he advised and pointed out that the OCT visualizes vitreous in real time, and because of this the need for air or triamcinolone staining is eliminated.
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In the demonstration of a case, he tamponaded the vitreous with a viscoelastic agent and then converted the opening into a posterior rhexis and performed an anterior vitrectomy.
In cases of traumatic cataracts, using OCT, the surgeon can easily differentiate lens material from vitreous. “This integrated OCT is a very useful technology for that,” he stated.
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Cases of intumescent cataracts are always problematic because of the presence of fissures filled with fluid that are under pressure. Upon entering the eye, the fluid is released rapidly, which results in a tear to the equatorial region. To counter this, Dr. Nischal simultaneously uses an irrigating cannula and an MVR blade or needle.
“When I enter the eye, I aspirate at 100%, which results in a controlled tear,” he said. This procedures eliminates the lakes of fluid, which helps control the surgery.
A pearl for performing pediatric surgery is recognizing that removal of the lens matter results in forward bowing of the posterior capsule due to positive vitreous pressure.
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“In this scenario, the posterior capsule is being pushed into the anterior chamber,” Dr. Nischal said. “For novice surgeons learning pediatric cataract surgery, this is not readily apparent. I have seen many fellows enter the eye with an instrument and inadvertently hit the posterior capsule.”
Using integrated OCT provides surgeons with a much better understanding of what is happening in the eye.
Another pearl involves creating a posterior capsulorhexis in children, which differs from adult cataract surgery where the posterior capsule is invariably left intact.
In children, an intact posterior capsule will opacify. Once a posterior capsulorhexis is done and the lens placed in the capsular bag, the viscoelastic is removed.
At this time, Dr. Nischal explained that the infusion bottle is lowered so that the pressure of the infusion does not push the IOL through the posterior capsular opening into the vitreous.
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Finally, he described a highly complex case of a 4-year-old boy who ran into the end of a kitchen knife, which resulted in a traumatic cataract and scarring and the need for a corneal transplant and cataract removal.
Dr. Nischal planned a dual surgery, which would not have been possible before OCT was integrated into the process, which visualized the stalk between the damaged lens and the scarred cornea.
This allowed the severing of the stalk and inflation of the anterior chamber with viscoelastic.
Dr. Nischal said the cataract was removed, an IOL placed in the bag and the corneal graft completed.
“The availability of this technology changed the outcome for this child,” he concluded.
Read more by Lynda Charters
Ken K. Nischal, MD, MBBS, FRCOphth
Dr. Nischal reported receiving honoraria from Carl Zeiss Meditec Inc.