March 2016

 

COVER FEATURE

 

Intracorneal inlays

Presbyopia inlays at the outset: Getting the near view


by Maxine Lipner EyeWorld Senior Contributing Writer

 
   
Red reflex of a KAMRA

Red reflex of a KAMRA inlay in situ Source: Perry Binder, MD

The Flexivue Microlens The Flexivue Microlens Source: Gustavo Tamayo, MD

A look back at corneal inlay development and a look ahead to where they may best fit in the realm of presbyopia treatment

With the ubiquitous problem of presbyopia always looming, approaches to correct this have a ready market. Recently, several corneal inlays, the KAMRA (AcuFocus, Irvine, Calif.), the Raindrop Near Vision Inlay (ReVision Optics, Lake Forest, Calif.), the Flexivue Microlens (Presbia, Dublin), and the ICOLENS (Neoptics, Hunenberg, Switzerland), have emerged ready to help this ever-growing population. For many years the treatment standard for presbyopia in the U.S. was monovision, whether this was done with corneal laser surgery or implants, according to Daniel Durrie, MD, professor of ophthalmology, University of Kansas Medical Center, and president, Durrie Vision, Overland Park, Kan. Monovision worksmany surgeons endorse it, Dr. Durrie said. But when you focus 1 eye up close and the other far away, there is some compromise in stereopsissome decrease in distance vison in the monovision eye. Also, there is some neuroadaptation that can take months for some patients. While other solutions have been tried, nothing else has caught on. As a result, monovision has been the chief go-to procedure here, he noted.

Inlays at the start

Corneal inlays have made strides in the presbyopic population. Development of the KAMRA inlay started 13 years ago. It went through several iterations of design and then started FDA clinical trials 9 years ago, and it has been available internationally since 2011, Dr. Durrie said. This was FDA approved in April 2015. With 2 other inlays, the Raindrop and the Presbia, now in clinical trials in the U.S., interest is mounting. Were starting to have a lot of interest from ophthalmic surgeons on where this is going to fit within our treatment suggestions for patients with presbyopia, Dr. Durrie said. While all the inlays are geared to change the point of focus of the near objects, they actually do this in 1 of 3 different ways, said Gustavo Tamayo, MD, director, Bogota Laser Center, Bogota, Colombia. The KAMRA works with the pinhole effect. The Flexivue Microlens works with a refractive addition to the cornea, Dr. Tamayo said, adding that it is akin to a near add in bifocals. As for the Raindrop Near Vision Inlay, it works by increasing the bulk of the cornea, thereby increasing its refractive index.

Perry Binder, MD, clinical professor, Gavin Herbert Eye Institute, University of California, Irvine, Calif., pointed out that of these inlay approaches, only the one that increases the depth of focus, the KAMRA inlay, is age-insensitive. The others, the Raindrop, the Flexivue, and the ICOLENS, work primarily by correcting a fixed focal length, he noted. To get a change in correction with these inlays as patients get older, youve got to change the inlay or go to spectacles, contact lenses, or PRK, Dr. Binder said. Depth of focus stays foreverthat does not change irrespective of age. I think current inlay models are all viable, and they probably will be used for different patients, Dr. Durrie said. The KAMRA inlay has been the most flexible because of the depth-of-focus principle and because it was the first to get approval and has the highest volume. FDA clinical investigators found that the KAMRA inlay did improve near vision, with very little compromise to distance, Dr. Durrie reported. I have patients who are 9 years postop and theyre still seeing well, so it seems to be quite stable over time, he said, adding that this also works well with lens replacement. You can leave the inlay in place and go to lens procedures and the depth-of-focus principle still works, he said. Thats comforting to both doctors and patients that you dont have to look at taking it out down the road once patients need a lens implant. On the other hand, it is not a problem if it does need to be removed. That was one of the positives that came out of the clinical trialsthat if the inlay was removed, the patient returned to the preoperative best corrected vision in almost all cases, Dr. Durrie said.

The negatives are that its newer and more expensive for the patient than monovision and that neuroadaptation is required. The vision isnt instantly recoveredits recovered over the first month, Dr. Durrie said. But patients dont seem to care because its getting rid of their reading glasses. If they have to wear their reading glasses for a couple more weeks and then get out of them, thats fine with them. In Dr. Durries experience, 15% of patients were out of their reading glasses as early as the first week, and everyone had reached that mark by the end of the first month. Dr. Tamayo mainly uses the Flexivue inlay. While he has used other inlays before, he likes the idea that with the Flexivue, the presbyopic correction is more in the periphery. I think the decrease in contrast sensitivity with visual acuity is less with he Flexivue, he said, adding that contrast visual acuity decreases in all of the inlays, as well as all of the multifocals and other intraocular lenses. It decreases because it creates a change in the refraction from the center to the periphery, he explained. Dr. Tamayo prefers the Flexivue because it respects the center of the cornea. Its a small center, but it respects this, he said. He reserves the inlays for emmetropic patients with 20/20 distance vision who would like to correct their near vision and who are not older than age 56. I consider the inlays as a factor to help the accommodation but not as a total replacement of accommodation, he said. For patients older than 56, I do not consider inlays as a solution. A second very important factor is the patients willingness to lose a little bit of distance vision in the non-dominant eye in order to gain some near acuity. Those patients who pass the test of monovision with a contact lens are the ones who I consider for this option, he said.

Comparing alternatives

Dr. Tamayo pointed out that the inlay can offer a patient more distance than monovision alone can. Real monovision implies a complete loss of distance vision in the non-dominant eye for gain in near, Dr. Tamayo said, adding that with inlays, the loss of distance vision is less than with monovision. With inlays, this is between 10 and 25%, whereas with monovision, which puts the patient at about 2 D in the non-dominant eye, there is more than a 50% loss of distance vision. I think that this form of modified monovision (with the inlay) is far better than the monovision that we used to do in the past, Dr. Tamayo said. Dr. Binder concurs that inlays are for those who dont want the loss of distance acuity. This is well-suited for those who want to be able to see up close but who still need to be able to see pretty well at distance, he noted. For instance, a plumber might benefit more from the inlay approach than a pharmacist. To help determine if a patient might benefit from the KAMRA, a pinhole can be used to help demonstrate what a patients distance and near vision will be like, he explained.

In Dr. Binders view, corneal inlays offer perks over refractive lens exchange with a multifocal IOL. The main difference would be the quality of the vision in terms of glare, halos, and dysphotopsia risks, he said, adding that the crispness of the vision at different distances is also a factor. Dr. Binder finds that while multifocal IOLs give good quality distance vision, the near or intermediate vision can be variable and might not be as good compared to an inlays. This can be compounded by the fact that the adverse optical side effects at night can sometimes be worse with multifocals. While there can be some optical issues with inlays, Dr. Binder said that published literature shows that patients dont report the optical side effects as much as they do with multifocal lenses. Also, a big advantage with inlays is if you put a multifocal lens in and the patient doesnt like it or its the wrong power, youre stuck with either doing surgery over that lens or more commonly the lens is exchanged, Dr. Binder said, adding that if patients dont like the inlay, its simple to remove and doesnt have the risk of going inside the eye. On average, patients get less than 1 D of accommodation with some of the accommodative lenses, Dr. Binder said. If the patients dont like the intraocular lens for whatever reason, youre talking surgerythats a big disadvantage. Going forward, Dr. Binder expects the inlays to continue to make inroads in the U.S. as these wind their way through the FDA approval process. I think the Raindrop is going to come nextI think its about 2 years away from submission, Dr. Binder said. Meanwhile, the Flexivue remains behind in the approval process, and the ICOLENS doesnt have any FDA studies ongoing. Its a European company so I think theyre going to stick to European sites, he said.

Presbyopia inlays article summaryEditors note: Dr. Binder and Dr. Durrie have financial interests with AcuFocus. Dr. Tamayo has financial interests with Abbott Medical Optics (Abbott Medical Optics) and Presbia.

Contact information

Binder: garrett23@aol.com
Durrie: ddurrie@durrievision.com
Tamayo: gtvotmy@telecorp.net

Presbyopia inlays at the outset Presbyopia inlays at the outset
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