March 2013

 

CATARACT

 

Lens prototype could avert negative dysphotopsia


by Erin L. Boyle EyeWorld Senior Staff Writer

   
Anti-dysphotopic IOL design

Masket anti-dysphotopic IOL design in cross section from patent application. Note that the circle 6C identifies an annular groove on the peripheral portion of the anterior surface of the optic. The groove receives the anterior capsulotomy, allowing the rim of the optic to overhang the anterior capsule edge.

Morcher prototype anti-dysphotopic IOL Side view of Morcher prototype anti- dysphotopic IOL

Scanning EM Scanning EM of haptic-optic junction of Morcher prototype anti-dysphotopic IOL. Note the peripheral groove.

anti-dysphotopic IOL in pig eye Morcher prototype anti-dysphotopic IOL in pig eye following femtosecond laser- assisted anterior capsulorhexis

anti-dysphotopic IOL OCT view of in situ Morcher prototype anti-dysphotopic IOL in pig eye following femtosecond laser-assisted anterior capsulorhexis with Catalys laser. Note the capture of anterior capsule in the peripheral groove.

Source (all): Samuel Masket, M.D.

After considerable research on the origins and prevention of negative dysphotopsia (ND), a physician has a patent application pending for a prototype posterior chamber IOL that could assist in negating the post-cataract surgery phenomenon. "The project is going forward," said Samuel Masket, M.D., clinical professor of ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles. "We've written the theories, we've talked about our clinical experience, and now I have designed a lens that will hopefully preclude the symptoms. It's the next step." Dr. Masket has been published on the topic, investigating how and why patients might have ND. The lens is part of his research, incorporating all that he has learned as he has examined the topic.

Research

In a July 2011 article that Drs. Masket and Fram published in the Journal of Cataract and Refractive Surgery, they examined four surgical methods of managing pseudophakic ND in 12 eyes of 11 patients. Those methods were the following: secondary piggyback IOL implantation, reverse optic capture, in-the-bag IOL exchange, and reducing posterior chamber depth by iris suture fixation. Ultrasound biomicroscopy was employed to analyze posterior chamber anatomy.

Drs. Masket and Fram found that none of the three patients who had in-the-bag IOL exchange or iris suture fixation of the capsular bag-IOL complex improved, even with a different IOL material or edge design in IOL exchange or "UBM confirmation of posterior chamber collapse in the case of iris suture fixation of the capsular bag-IOL complex." But all 10 patients who had a piggyback IOL implantation or reverse optic capture had partial or total resolution of symptoms by three months. Subsequently, they have treated an additional 20 patients with similar results.

"Consistent with a new hypothesis, resolution of [ND] symptoms depended on IOL coverage of the anterior capsule edge rather than on collapse of the posterior chamber alone. Furthermore, [ND] was not attributed to a particular IOL material or edge design, although the prevalence may be higher with high index of refraction acrylic IOLs" they found.

The findings of this study led to a new theory into the etiology of ND, which assisted Dr. Masket in the design of his prototype lens. ND is frustrating to treat, Dr. Masket said in an interview, because it is associated with the incision in any location, any or all kinds of in-the-bag IOLs and occurs only when cataract surgery is anatomically perfect. However, it has not appeared with a sulcus-placed PC IOL or an anterior chamber IOL, he said. He demonstrated one specific ND patient case.

"This patient had a single-piece acrylic lens, had ND, was miserable, and was referred to a second surgeon, who exchanged the original IOL for a single-piece collamer lens placed in the capsule bag and the ND symptoms are exactly the same. This patient example demonstrates that ND is not IOL-specific," he said.

A subsequent laboratory investigation, published in the Journal of Biomedical Optics, employing ray-tracing analysis largely confirmed the clinical findings.

Lens

"What our clinical research has demonstrated to us is that [ND] seemingly will not occur if the lens optic or lens optic edge sits on top of the anterior capsule, rather than the traditional in-the-bag concept," Dr. Masket said. "So, I conceived of an IOL that has a mushroom cap, created by an annular groove off the anterior surface that is designed to capture the anterior capsulotomy. The essence of the design is that it still allows any optic concept, asphericity, toricity, multifocality, and desired haptic design.

"It can be applied to any lens style, but by placing a rim of the optic anterior to the anterior capsulotomy, if our theories are correct, the patient should not suffer [ND] with this design," he said.

Dr. Masket is now working with Morcher (Stuttgart, Germany) and H. Burkhard Dick, M.D., chairman, University Eye Hospital Bochum, Germany, to develop and implant the lens, respectively. The design that Morcher is pursuing is close to Dr. Masket's, which he calls an anti-dysphotopic IOL. Morcher is currently in the process of seeking a CE mark for the lens. When the lens receives a CE marking, Dr. Dick's practice will be the study center, where he will use the Catalys (OptiMedica, Sunnyvale, Calif.) to perform femtosecond laser-assisted cataract surgery for the perfect capsulorhexis needed for well-centered implantation.

References

Masket S, Fram NR. Pseudophakic negative dysphotopsia: Surgical management and new theory of etiology. J Cataract Refract Surg. 2011 Jul;37(7):1199-207.

Hong X, Liu Y, Karakelle M, Masket S, Fram NR. Ray-tracing optical modeling of negative dysphotopsia. J Biomed Opt. 2011 Dec;16(12):125001-7

Editors' note: Dr. Masket has a patent approval pending for the design of the lens prototype discussed in the article. He has financial interests with Alcon (Fort Worth, Texas).

Contact information

Masket: 310-229-1220, avcmasket@aol.com

Lens prototype could avert negative dysphotopsia Lens prototype could avert negative dysphotopsia
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