December 2018

NEWS & OPINION

Research highlight
Surgical remedy for negative dysphotopsia


by Maxine Lipner EyeWorld Senior Contributing Writer


Secondary reverse optic capture in a symptomatic patient
Source: Samuel Masket, MD

 

For patients with complaints of negative dysphotopsia (ND), a surgical strategy of secondary reverse (anterior) optic capture can remedy the situation, according to Samuel Masket, MD, Los Angeles. Dr. Masket reported on study results1 in remedying negative dysphotopsia in the Journal of Cataract and Refractive Surgery. In all but one case of secondary reverse optic capture, this technique was successful.
In cases of negative dysphotopsia, the typical complaint centers around a dark temporal crescent or line in the periphery of patients’ vision. One of the ironies with the condition is its association with a well-centered posterior chamber lens in the capsule bag with an overlapping anterior capsulotomy for 360 degrees. “We only see it under what we consider to be anatomically perfect postoperative circumstances,” Dr. Masket said, adding that if there’s significant decentration, significant tilt from capsule damage, ND tends not to occur.

Shifting theories

Theories on the condition have abounded over the years. “Negative dysphotopsia was first reported in 2000 by Jim Davison, MD,” Dr. Masket said. “It corresponded to the same time that acrylic IOLs became popular in the market.” The assumption was that the chief cause of ND was the single- or multi-piece acrylic IOL with a high index of refraction and a square edge; these characteristics were already associated with positive dysphotopsia (PD).
With the assumption of a particular lens style being responsible, many practitioners, including Dr. Masket, exchanged (bag to bag) such acrylic IOLs for round, silicone IOLs with a low index of refraction for symptomatic patients. “In our experience, we had no success with this strategy,” Dr. Masket said. Meanwhile, an investigation2 done by Peter Vamosi, MD, helped to enhance Dr. Masket’s understanding. Dr. Vamosi reported that if he exchanged the lens in the bag for one made of a different lens material, he had no success. However, if he exchanged the in the bag lens for one in the sulcus, he was successful. In his study, position of the IOL was paramount, not the material or the design.
Another theory was based on the expanded space between the back of the iris and the front of the lens implant (posterior chamber) in the pseudophakic eye. Surgeons filled this gap with a piggyback IOL, with moderate success. “It’s about 70% successful,” Dr. Masket said. However, in a case where he attempted to shallow the posterior chamber by fixating the lens bag to the iris, he found that this failed to help. In addition, the Vamosi study indicated that the depth of the posterior chamber was identical in both the symptomatic patient group and the controls, disproving the theory that the expanded posterior chamber was causal for ND.
Dr. Masket noted that during the late 1980s surgeons not only changed the lenses they were implanting but also began incorporating capsulorhexis into their surgeries. “Prior to that we used can-opener capsulotomies,” he said, adding that with this early approach the majority of lenses ended up with one loop in and one loop out of the bag. “We started to look at the relationship of the anterior capsulotomy to the anterior surface of the IOL as being one potential site for induction of negative dysphotopsia.”
Dr. Masket decided that he would try a new approach by placing the optic in front of the capsule, rather than behind the capsule while leaving the loops in the bag for support. “That strategy worked extremely well,” he said.

Studying treatments

That method, as well as other approaches, were considered in the recent consecutive surgical case series of 37 patients with chronic ND. Investigators looked at how effective such treatments were for alleviating negative dysphotopsia.
For the 22 patients who underwent reverse optic capture as a secondary procedure, investigators determined that this was almost always successful. “We’ve had success in all but one case,” Dr. Masket said, adding that in 21 primary cases they’ve been 100% successful.
The investigators, including Dr. Masket’s partner, Nicole Fram, MD, also evaluated which IOLs were involved in cases of negative dysphotopsia and found that virtually all IOLs could be associated with this. They determined that in their series, 23% of IOLs were silicone and 12.8% of these had round edges. “I hope that we have been successful in dispelling the myth that the square-edge high index of refraction acrylic IOL is the culprit,” Dr. Masket said. “ND appears to be related to how the IOL is positioned in the eye; if you take the same in the bag lens that induces negative dysphotopsia and pop that optic in front of the capsule, in all likelihood the negative dysphotopsia is going to go away.”
When it comes to primary reverse optic capture (for second eyes of patients with ND in the previously operated eye), while successful at dispelling ND, there can be issues.. “Without the optic in the capsule bag after surgery, the bag tends to shrink and get rapid onset fibrotic PCO,” Dr. Masket said. In their series, all cases of primary reverse optic capture required laser posterior capsulotomy by 3 months after surgery. There can also be long-term concerns about positional stability of sulcus-placed lenses and iris chafing.
This led Dr. Masket to design a lens that would mimic reverse optic capture, but one in which the bulk of the lens would remain in the capsule bag; however, a lip or cap would overlie the anterior capsule, preventing patients from getting negative dysphotopsia. This lens, the 90 S (Morcher, Stuttgart, Germany), includes a groove that accepts the anterior capsule, he continued, adding that it has been in clinical trials in Europe. In essence the IOL is fixated by the anterior capsulotomy. Approximately 150 of these IOLs have been implanted and none have experienced ND.
Dr. Masket hopes that practitioners take home the message that ND is a condition that should be on their radar as one that occurs when surgery has actually been perfect. Patients need to understand that they will likely improve over time, but if ND persists, they can be helped surgically. ND should not be ignored as it may occur in 100,000 new cases annually in the U.S. alone. Hopefully, practitioners can explain ND to patients and support them.
“I would hope that the manufacturing sector will do better on this,” Dr. Masket said. “We can’t have 100,000 patients annually with chronic ND who had ‘perfect surgery’ but can be very unhappy,” he said.

References

1. Masket S, et al. Surgical management of negative dysphotopsia. J Cataract Refract Surg. 2018;44:6–16.
2. Vamosi P, et al. Intraocular lens exchange in patients with negative dysphotopsia symptoms. J Cataract Refract Surg. 2010;36: 418–24.

Editors’ note: Dr. Masket has financial interests with Morcher.

Contact information

Masket
: avcmasket@aol.com

Surgical remedy for negative dysphotopsia Surgical remedy for negative dysphotopsia
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