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Modified bag-in-the-lens cataract surgery incorporates bean-shaped ring segments
The approach further reinforces the capsule and facilitates lens placement.
The standard bag-in-the-lens IOL technique has been modified by inserting custom-designed bean-shaped segments to provide capsular tension over the area of defect and a central aperture designed to support the lens.
The modification is the culmination of a collaboration between Olaf Morcher, CEO of German lens manufacturer Morcher GmbH, and clinicians, including Marie-José Tassignon, MD, PhD, FEBO.
“We initially worked on another project involving an artificial capsule that required scleral suturing at four cardinal points,” Tassignon told Ocular Surgery News. “That device was tried but found not to be practical.”
Morcher then devised the idea of a bean-shaped ring, which was slightly adapted in shape to fit sulcus-to-sulcus diameters of 11 mm to 14 mm. Tassignon first presented the modified technique at the European Society of Ophthalmology Congress in 2011, and the current shape of the PMMA ring was finalized that year.
Marie-José Tassignon
Increased stability
“I wanted to increase the stability and the use of the bag-in-the lens (BIL) technique in eyes with loose zonules,” Tassignon said. “Before this recent invention, in most cases I implanted an iris clip lens positioned in the posterior chamber. However, the disadvantage of this lens is that it leaves the eye globe as one large cavity with the risk of vitreous prolapse into the anterior chamber.”
In addition, a 6-mm incision is necessary with an iris clip lens. In contrast, bean-shaped rings in conjunction with BIL “allow for a nice aphakia correction” through a 2.5- to 2.8-mm incision, Tassignon said. Moreover, these rings can be positioned in the capsular bag or in the sulcus, depending on the stability of the zonular fibers.
According to Tassignon, ideal candidates for the modified technique are patients with acquired or metabolic partial zonular lysis.
“The surgeon should first master the classic BIL implantation technique before starting to use this kind of medical device,” Tassignon said. “Being familiar with capsule suspension using iris hooks or other suspension devices, as well as proficiency in implanting capsule tension rings of any sort, is also important.”
The most challenging step of the technique is implanting the bean-shaped rings after performing the anterior and posterior capsulorrhexes.
“The rings must then be glided between both capsular blades, without inflating the capsular bag,” Tassignon said. “This requires practice.”
Other advantages
Besides the advantage of a smaller incision, the lens is placed at its most natural position, which allows a more predictable refractive outcome, Tassignon said.
Furthermore, the vitreous is better maintained in the posterior segment of the eye, thus reducing the risk for retinal tear formation and subsequent retinal detachments, she said. Less scleral suturing is also needed.
“Because the rings are manufactured out of PMMA, they will last for many years,” Tassignon said. “This is a huge benefit over all types of suturing material. You also have the possibility to center the optic of the BIL based on the ciliary sulcus.”
A description of the modified technique and a case study appeared in the Journal of Cataract and Refractive Surgery. Over the past 2 years, Tassignon has treated about a dozen patients.
“When I use the device in patients without any capsule support, it does not work,” she said. “This is still the most difficult group of patients. That is the reason why I now use an artificial iris that I equip with the BIL and position the composite in the ciliary sulcus.”
When the rings are implanted according to the indications, no adverse events of the modified technique have been observed by Tassignon. “The biomaterial is well known and biocompatible,” she said. The size of the rings can also easily be defined preoperatively.
“A novel technique like this needs approval by my peers,” Tassignon said. “I hope other colleagues will take the challenge to use the bean-shaped rings.” – by Bob Kronemyer