IOLs bring benefits
Capsulotomy-centred IOLs could improve image quality and reduce complications
One year after monofocal BIL implantation showing perfect pupillary centration and LEC proliferation in the peripheral capsular bag only and optimal optic light transmission. Courtesy of Marie Jose Tassignon, MD.
One capsulotomy-centred intraocular lens (IOL), the bag-in-the-lens (BIL), has been shown to eliminate posterior capsule opacification (PCO), and another may eliminate negative dysphotopsia (ND), leading clinicians told the Ophthalmology Futures European Forum 2016.
IOLs with grooves that snap into precisely placed anterior capsulotomies may also improve quality of vision, especially with centration-dependent multifocal and extended-depth-of-focus IOLs, though the evidence is not yet clear.
In use for 17 years, the BIL (Morcher) features a groove around the edge that fits into both an anterior and posterior capsulotomy, supporting the lens while collapsing and sealing the capsular bag. The original goal was completely eliminating PCO, which the BIL does, along with ND and fibrotic proliferation, said designer Marie-José Tassignon MD, PhD, FEBO of University Hospital Antwerp, Belgium. Long-term stable lens centration is an added benefit.
Femtosecond lasers cutting precisely shaped and positioned anterior and posterior capsulotomies could potentially make more effective use of the stability capsule centration provides, Dr Tassignon said.
“New capsule-centred IOLs are coming up and I think this is just the beginning of this new age. There are many advantages of capsules centred in the eye,” she added.
Eliminating ND was the reason Samuel Masket MD, of the University of California – Los Angeles, USA, designed a lens with a groove in the optic that overlaps the anterior capsulotomy (Morcher 90S). The idea came from his success eliminating refractory ND, which appears as a peripheral shadow, by implanting conventional three-piece lenses with the optic captured in front of the capsulotomy. Out of 88 patients implanted with the new lens none reported ND, he noted. Among the series is one case where a traditional IOL was exchanged for the grooved IOL (Morcher 90S) and the patient noted complete relief of symptoms. “ND is an annoying optical complication of present day technology. It is best prevented if possible,” said Dr Masket.
Dr Masket sees other potential advantages. With the capsulotomy fixed in the groove and supporting the IOL, capsule contraction is eliminated, as is rotation of toric IOLs. Moreover, IOL tilt and decentration will not occur. “Additionally, if we can centre the lens on the visual axis, we can fully eliminate induced higher order aberrations with multifocal or aspheric IOLs,” he said. All of these facets are best achieved with an automated anterior capsulotomy, most typically achieved presently with the femtosecond laser.
However, the extra manipulation and pressure required to implant capsulotomy-centred lenses risks damaging the capsulotomy, noted Boris Malyugin MD, PhD, of the S. Fyodorov Eye Microsurgery Complex, Moscow, Russia. While he believes such IOLs could improve stability and lens position predictability, it is not clear whether the capsulotomy should be centred on the limbus, the capsule itself or the presumed visual axis.
For standard monofocal lenses the extra stability and precision may not be needed, said Paul Rosen FRCOphth, MBA, Oxford Eye Hospital, London, UK.
“Where it becomes a big issue is with multifocal, bifocal and toric IOLs. I think that is the direction you want to go with (capsulotomy-centred) lenses,” he said.
Whether capsulotomy-centred lenses are more stable may depend on their design, said Oliver Findl MD, of Hanusch Hospital, Vienna, Austria. Lenses with haptics in the bag, such as the Masket lens, may still be prone to axis shift and capsule contraction while the BIL probably is not.
The BIL has another issue, Dr Findl added. “I think most surgeons don’t feel comfortable, even if they have a femtosecond laser, putting the lens through two capsulotomies with the vitreous just behind.”
This could lead to more complications. However, new intraoperative imaging technologies can visualise the posterior capsule and anterior vitreous hyaloid, which makes posterior capsulotomy safe, Dr Tassignon noted.
Lens tilt is also not well understood, Dr Findl said. His research shows some patients have physiologically tilted natural lenses before surgery, and end up with tilted implants after surgery. “There are still things we do not understand properly. I’m not sure, even if we use these kinds of lenses, that we will take care of all these issues,” he added.
Dr Malyugin agreed. “There are so many unanswered questions. We do not have enough data to show which technology will prevail. A lot of research needs to be done.”
Marie-José Tassignon: firstname.lastname@example.org
Samuel Masket: email@example.com
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Paul Rosen: email@example.com
Oliver Findl: firstname.lastname@example.org