Novel Intraocular Lens May Prevent Negative Dysphotopsia

Caroline Helwick

November 13, 2017

NEW ORLEANS  — A novel intraocular lens (IOL) appears to prevent negative dysphotopsia associated with cataract surgery, according to prospective studies in 100 patients.

Negative dysphotopsia (ND), or shadows in the patient's field of view, occurs after cataract surgery in about 15% of patients. Until the development of this IOL, there was little to no way to prevent this complication, said Samuel Masket, MD, at the American Academy of Ophthalmology (AAO) 2017 Annual Meeting.

Dr Masket, from the of the University of California Los Angeles Stein Eye Institute, won the "Best Original Paper" on the topic of cataracts. During his presentation, he described results achieved with the Masket anti-dysphotopic IOL. It is manufactured as model 90S by Morcher GmbH and is CE marked, meaning it can now be marketed in the European Union.   

The Problem of Negative Dysphotopsia

According to Dr Masket, ND can be induced by any "in the bag" IOL with the anterior capsulotomy edge overlying the optic. In a previous study he led, currently in press, 40 eyes with chronic ND requiring a second cataract surgery revealed no preference for one type or brand of standard IOL over another. 

Regardless of the cause, he said, his experience has shown that "ND is prevented, relieved, or improved when the IOL optic edge overlies the anterior capsulotomy, either sulcus-placed or with reverse optic capture…The optic is anterior to the capsule edge but the haptics remain within the capsule bag." These observations led Dr Masket to design an antidysphotopic IOL intended to match his clinical experience with ND.  

His "capsulotomy-fixated" IOL features a groove on the anterior optic that captures the capsulotomy, he explained. Part of the optic overlies the capsule, rather than vice versa, and the lens is essentially fixated by the anterior capsule.

"For reasons that are not really clear, this prevents or reverses ND. If the optic is in front of the capsule, the symptoms will either not develop or will be improved. That's what my design achieves," he told Medscape Medical News.

Evolution of Three Versions of the 90S IOL

Clinical trials of three versions of the 90S IOL were conducted at multiple sites in Europe in patients scheduled for routine cataract surgery. The primary outcome measure was development of dysphotopsia as determined by a patient questionnaire the investigators developed. Along with ND, the researchers looked for other complications, such as iris chafe, "given that the optic projects in front of the capsule," he said.

The first two versions eliminated ND but did not eliminate capsule block or iris-optic capture. In the original version, none of 39 patients developed ND, but 3 had capsule block and 2 had iris-optic capture, in which the iris was "caught in the margin of the groove," he said.

The lens was then modified to include fixation holes that made it easier for surgeons to capture the optic and an "escape route" that prevents the entrapment of fluid.  Version 2 of 90S was implanted in 48 patients, after which there were no cases of ND or capsule block; however, 5 cases of iris-optic capture occurred. Among the 7 cases of iris-optic capture in the first 87 patients to receive the first 2 versions of the 90S, 5 patients required surgery and 2 requested explantation of the IOL.

The researchers believed the chief underlying cause was the use of the thick hydrophilic lens. Their idea for correcting this in version 3 was to enlarge the anterior part of the optic to 6.4 mm and to use a myotic at the time of surgery in order to keep the pupil small in the early postoperative period. This refinement has apparently worked. To date, 13 patients have been implanted with version 3 of the 90S, and none has developed ND, capsule block, or iris-optic capture, Dr Masket reported. 

Proof of Concept Shown

Altogether, after 100 implantations of the 90S IOL during cataract surgery, no cases of ND have been observed. "We think that gives us adequate proof of concept," he said.

Six patients showed mild, nondebilitating positive dysphotopsia. No patient developed iris chafe, capsule block has been eliminated as a complication, and the risk for iris-optic capture "has clearly been reduced and possibly eliminated," he said.

Two patients had the 90S implanted as an exchange for a previous IOL that had resulted in ND, and in both patients the ND was alleviated by the 90S.  

"Our current plan is to implant another 30 to 50 of the 90S model, and if we don't encounter additional problems, we will release this device for general use in Europe," Dr Masket said.

An Advance in the Field

Session moderator Surendra Basti, MBBS, director of the cataract service and professor of ophthalmology at Northwestern University School of Medicine, Chicago, Illinois, called the 90S a "very innovative design and a large paradigm shift" for addressing a problem that is common in cataract surgery.

While about 15% of patients will report ND, "the good news is that some of these patients will not notice these symptoms as much over time," he said. "In reality, about 5% of patients will remain very unhappy over this, but certainly in the early postop period it is a common complaint."

Panelist Adi Abulafia, MD, director of cataract services at Shaare Zedek Medical Center in Jerusalem, Israel, told Dr Masket, "I congratulate you on the lens design. All of us as surgeons have been waiting for a lens that will have no ND for our patients." 

Dr Masket disclosed relationships with Morcher GmbH, Accutome, Alcon Laboratories, Haag-Streit, MST Surgical, Ocular Science, Ocular Theraputix, PowerVision, and VisionCare Ophthalmic Technologies. Dr Basti and Dr Abulafia have disclosed no relevant financial relationships.

American Academy of Ophthalmology (AAO) 2017 Annual Meeting. Presented November 10, 2017.

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