June 2011

 

COVER FEATURE

 

The pioneer spirit: Unmapped presbyopia correction territories


by Maxine Lipner Senior EyeWorld Contributing Editor

   

Femtosecond laser pulses

One approach to correcting presbyopia involves lens softening with the femtosecond laser. Pictured here: Femtosecond laser pulses in a living human lens, creating bubbles immediately after placement in a waffle pattern Source: Ronald R. Krueger, M.D.

In addition to more traditional approaches to correcting presbyopia, such as lens- or corneal-based technology, an innovative frontier is emerging. Inroads are being made in everything from femtosecond lens softening to enhancement of scleral plasticity. EyeWorld took a closer look at some of these to see how they might eventually civilize presbyopic territory.

Smithing away at lens softening

One innovative new approach is using the LensAR femtosecond laser (Winter Park, Fla.) to soften the lens nucleus. The concept here is to place femtosecond pulses in the nucleus, according to Ronald R. Krueger, M.D., medical director of refractive surgery, Cole Eye Institute, Cleveland, and professor of ophthalmology, Cleveland Clinic. "The lens nucleus is then softened as compared to the harder nuclear state that might have been there before, and that would allow for more flexibility of the crystalline lens," Dr. Krueger said. With the technique, the laser will focus very localized pulses along any specific geographic pattern in whatever volume needed. "We don't have to cut through the anterior part of the lens to get in the middle of itthe laser goes right to the middle," Dr. Krueger said. "We can put pulses in any number of different patterns in order to try and make the lens softer so that it's more flexible."

Results so far, however, have been modest and somewhat unpredictable. "We've shown that we could make the lens more flexible experimentally, but in treating patients we have not seen any consistent return of that accommodative mechanism," Dr. Krueger said. "What we have seen is that we can put the laser pulses inside the lens without having a cataract form from them."

There have been a few cases where the technique has shown promise. "We have seen a few cases where we got 1.5 D or so of potential accommodation change with objective measurement," Dr. Krueger said. "But many other cases we haven't seen any change." Investigators are now working on the patterns to try and come up with one that they hope will work the most effectively.

Dr. Krueger thinks that successes that LensAR has had of late in using the femtosecond technology for cataract surgery will provide the financial foundation to continue working on accommodation restoration. "In time, I think that we will eventually be able to solve this issue," he said.

D. Rex Hamilton, M.D., assistant clinical professor of ophthalmology, and director, UCLA Laser Refractive Center, Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, is hopeful that this may eventually prove successful. "I think that it could be a potentially huge treatment because there are no incisions and it's minimally invasive in terms of risk of infection," he said. His one concern is making sure that the procedure does not heighten the risk of cataract development.

Liquid crystal in them there hills

Another new presbyopic option being considered, about which Dr. Hamilton feels less optimistic, are dynamic spectacles that utilize embedded liquid crystals. The new electronic glasses, called emPower (Pixel Optics, Roanoke, Va.), enable users to change the refraction by touching a sensor on the frame, according to Clay Musslewhite, director of marketing, Pixel Optics. Inserted between the lenses are liquid crystals, which can rearrange themselves and change the focusing power faster than the blink of an eye, Mr. Musslewhite said. There's also an automatic mode that can be used that activates an accelerometer built into the frame. This senses head tilt. "When the wearer is looking straight ahead, the electronic reading zone is off and when the wearer looks down, it turns it on automatically," Mr. Musslewhite said. This mode would have to be activated as well.

There are some who question just how robust this technology currently is for use in presbyopic patients and wonder if it will be too distracting to constantly be worrying about pushing a button or adjusting head position to change the status of the near vision. However, Mr. Musslewhite noted that studies with the glasses show that 75-80% of the time wearers are not reading something up close and when they are reading, it is usually for an extended 5-10 minute period. He finds that wearers like having the control. "With regular glasses everything is optimized around the fact that the reading power is always there," Mr. Musslewhite said. "But now they have the choice, and our feedback from our wearer studies is that they love that choice."

The scleral end of town

There are two distinct technologies concentrating on the scleraScleral Expansion Bands (Refocus Group, Dallas) and the LaserACE (Ace Vision Group, Silver Lake, Ohio)that are making presbyopic inroads. With the Scleral Expansion Band technique, segments are put into each of the oblique quadrants of the eye, according to Barrie D. Soloway, M.D., assistant professor of ophthalmology, New York Medical College, New York. The mechanism remains somewhat uncertain. "It appears as if it tightens the posterior zonules to allow for continued shape changes relating to the lens growth as being the problem more so than lens stiffness," Dr. Soloway said. The thinking is that with the lens growth, the circumlental space diminishes. Results have been encouraging. "At our FDA sites we're seeing a mean improvement of 2.91 lines of near acuity across all patients," Dr. Soloway said. "We've had up to seven lines of improvement." The technique, which doesn't affect distance vision, is targeted mainly toward the emmetrope. "The younger 45- to 60-year-old age range with 20/20 uncorrected distance vision is our target group," he said. While position of the implants has been somewhat problematic, Dr. Soloway sees this as becoming a lot better controlled. "We're about to submit to the FDA to begin using newer disposable sclerotomes, which are a lot easier to handle and to get in the right place," Dr. Soloway said. He expects to complete enrollment in the FDA trial by the end of the year and to monitor the patients for the next 2 years. "We're looking at submitting to the FDA some time in 2013 or early 2014."

The LaserACE procedure, meanwhile, restores the plasticity of the sclera, according to Marguerite B. McDonald, M.D., F.A.C.S., clinical professor of ophthalmology, New York University Langone Medical Center, New York. "The sclera plays a very important role in the accommodative process," Dr. McDonald said. "The zonules insert into the ciliary processes, which are attached to the sclera."

With this technique, a matrix of nine lesions - 600 microns spot size and 85-90% depth - in a patented diamond pattern is made in four quadrants to partially ablate the sclera in a critical zone right over the ciliary body. "These lesions start back 0.5 mm from the limbus and are placed in the oblique quadrants to avoid contact with the extraocular muscles," Dr. McDonald said. "Basically, it improves the resultant forces that the ciliary muscles have on the crystalline lens."

AnnMarie Hipsley, D.P.T., Ph.D., founder, Ace Vision Group, and inventor of LaserAce, stressed that the goal here is not to change the globe. "The effect is one of increased plasticity rather than expansion, and no implants are required. The procedure is not designed to increase circumlental space," she said.

"Our technology is changing the biomechanical properties of the sclera, making it more plastic and increasing the efficiency of the ciliary body and restoring the natural accommodative function without affecting refractive status," she said. Unlike scleral implants, the existing geometry of the globe is unaffected. Results have been promising. "Our results on almost 70 eyes out to 18 months show an average increase of accommodation of over 1.25 D, measured objectively with the i-trace system," Dr. Hipsley said. The most compelling result is that LaserACE data indicate an objective improvement in near and intermediate vision with no loss of distance vision. In fact, with some latent hyperopes, distance vision improved after the LaserACE procedure. Presbyopia correction article summary

Sheri L. Rowen, M.D., clinical assistant professor of ophthalmology, University of Maryland School of Medicine, Baltimore, and chief of ophthalmology, Mercy Medical Center, Baltimore, sees the procedure as helping to restore functional vision. Patients studied who were in the 40-60 age range started with about 1.5 D of accommodation. "They got up to a little above 3 D, so they gained about 1.5 D, which isn't bad considering that's what we give with the Crystalens (Bausch & Lomb, Rochester, N.Y.)," she said. "We all have a little bit of reserve and you include that and patients say, 'I can see J3 nowI can function.'"

The laser is already 510(k) approved and European Conformity marked. Dr. Hipsley is now focused on finishing international studies, where multi-year data indicate stability of the procedure. A comprehensive corroborative study is planned in Canada this year to provide additional objective accommodative data. Dr. Rick Potvin, Ace Vision's new chief scientific officer, is initiating a study of scleral biomechanics and plasticity to help elucidate the mechanism of action of the procedure. If the Canadian clinical data are confirmatory of earlier results, Dr. Hipsley will use these to support an Investigational Device Exemption in a 3-year clinical study for the FDA approval of the procedure.

Editors' note: Dr. Hamilton has no financial interests related to his comments. Drs. Hipsley, McDonald, and Rowen have financial interests with LaserACE. Dr. Krueger has a financial interest with LensAR. Mr. Musslewhite has a financial interest with Pixel Optics. Dr. Soloway has a financial interest with Refocus Group.

Contact information

Hamilton: hamillton@jsei.ucla.edu
Hipsley: ahipsley@acevisiongroup.com
McDonald: margueritemcdmd@aol.com
Musslewhite: cmusslewhite@pixeloptics.com
Krueger: krueger@ccf.org
Rowen: srowen10@gmail.com
Soloway: bds@ihateglasses.com

Unmapped presbyopia correction territories Unmapped presbyopia correction territories
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