Inlays making inroads in cornea-based presbyopia correction landscape

Presbyopia correction is widely considered one of the unmet needs of refractive cataract surgery, particularly at the corneal plane, but cornea-based methods may be viable alternatives to more entrenched lens-based approaches, according to some experts.

Current cornea-based methods include blended vision and monovision contact lenses, LASIK and PRK, and corneal inlays. Multifocal ablation is not approved in the U.S.

“The surgical correction of presbyopia represents a new frontier in anterior segment surgery. We think this is rapidly becoming its own subspecialty. As a result, we’re seeing new and exciting treatment modalities, both at the lens and the corneal plane,” George O. Waring IV, MD, OSN Technology Board Member, said.

Monovision has been the only established cornea-based presbyopia correction method in the U.S., according to John A. Hovanesian, MD, FACS, OSN Cataract Surgery Section Editor.

“Up until now, we’ve really only had monovision as a reasonable option just because multifocal lenses for the emmetropic presbyope have not been widely adopted, and because the alternative of multifocal ablation on the cornea with a laser is not approved in the U.S. and is very sparingly used outside the U.S.,” Hovanesian said.

Cornea-based methods such as corneal inlays have many advantages over lens-based approaches, according to Philip C. Hoopes Jr., MD. Hoopes performed the first implantations of the Kamra inlay (AcuFocus) in the U.S. in May, after the FDA approved the inlay for presbyopia correction.

“I think there’s a major role for cornea-based presbyopic correction that may have advantages over intraocular lens-based surgery,” Hoopes said. “With intraocular lens-based surgery, the surgeon must choose between monovision and multifocal vision. There are drawbacks to monovision and multifocal vision in terms of quality of distance vision and quality of night vision that we do not see with the corneal inlays.”

Image: Dishler J

Monovision, blended vision

Monovision, the only FDA approved LASIK option for correcting presbyopia, involves targeting one eye for distance vision and the other eye for near vision.

Blended vision involves minimal correction in the nondominant eye, resulting in less difference in dioptric power between the eyes, typically less than 2 D.

Modified monovision involves achieving monovision using bifocal contact lenses in which the power, lens fit or other lens parameters are modified to emphasize distance vision for one eye and near vision for the other eye, while maintaining a certain amount of binocular vision.

According to the U.S. Trends in Refractive Surgery: 2014 ISRS Survey, 59% of responding members preferred monovision for pre-cataract presbyopia, 23% preferred modified monovision, 5% preferred accommodating IOLs and 9% preferred multifocal IOLs.

“Previous cornea surgery for presbyopia has always included the use of monovision traditionally done with LASIK or PRK. There was a period where a technology called conductive keratoplasty gained popularity about 7 or 8 years ago, hoping to reshape the cornea and avoid removing tissue, also giving patients monovision,” Hoopes said.

Hovanesian said there are drawbacks to monovision, such as loss of depth perception.

“Sometimes patients try it at too young an age where it’s harder to adapt,” he said. “Then they are just biased against it. I’m a big fan of monovision and think that it checks a lot of boxes for being a valid method, but that’s if patients want it. For many people, they get sort of a false start with it.”

William B. Trattler, MD, OSN Technology Section Editor, said his primary presbyopia correction method is blended vision for patients in their 40s and 50s.

“I typically have patients test it out with a contact lens first to see if they are satisfied with their vision. Overall, patients do well,” Trattler said. “When we’re planning blended vision, we first perform a contact lens trial, where we target one eye for distance and we target the other eye for intermediate. If patients are happy with the vision, we use the same targets with the laser, either LASIK or PRK.”

According to Trattler, patients who undergo the blended vision contact lens trial and are satisfied with their vision will end up very happy with their final visual results after LASIK or surface ablation.

“The main difference between blended vision and monovision is that monovision is one eye distance and one eye near, between –1.5 D and –2.5 D,” Trattler said. “In blended vision, the goal is to make the difference between the two eyes a little bit less. There’s a little more binocularity. The difference in power between the two eyes is less, usually 0.75 D to 1.25 D.”

Cynthia Matossian, MD, an OSN Cataract Surgery Board Member, said she uses blended vision with a Lenstec hydrophilic acrylic IOL.

“For reasons that are still not clearly understood, separating the two eyes by only 0.75 D, you get terrific distance, terrific intermediate and functional near vision,” she said. “With this small interocular dioptric difference, the patients do not lose stereopsis and do not have much difficulty with night driving.”

Kamra inlay

Hoopes described corneal inlays as a viable alternative to monovision.

“The current therapies going forward will be the use of the corneal inlays, which allow us to place material within the cornea at a depth to 200 µm or 300 µm, that will give patients the ability to see distance and near vision,” Hoopes said. “Current procedures for cornea-based reading surgery would be attempting to go beyond monovision by allowing patients to keep their far vision and then gain reading vision.”

The Kamra inlay is poised to fill a global niche in cornea-based presbyopia correction, Hovanesian said.

“It’s going to allow us to explore, not just for the U.S. but for the world, what the market is for these technologies,” he said. “When a technology is approved elsewhere before it’s approved in the U.S., often the adoption is slow because those surgeons are waiting for U.S. approval, not only to show that the product is safe and effective but to see how U.S. surgeons behave through their use of the product. That’s now going to happen.”

The Kamra inlay, which uses a pinhole effect to increase depth of field, is inserted in the nondominant eye of a patient.

“Inlays are trying to achieve both eyes for distance vision, with the inlay eye getting the reading vision,” he said. “That’s what makes it truly different from monovision.”

The ideal candidate for the Kamra inlay is between 45 and 60 years of age and does not want to wear reading glasses, Hoopes said.

“They have to already have good uncorrected distance vision in each eye,” he said.

Hoopes noted that inlays can be removed, if necessary.

“The nice thing about the inlays being a cornea-based procedure is, should there be any need to remove the corneal inlay, it can be simply done in an outpatient setting, whereas removal of intraocular lenses does provide technical and procedural difficulties,” he said.

Trattler said the Kamra inlay extends range of vision while preserving depth perception.

“It appears to deliver a nice range of vision without losing depth perception. It is FDA approved, although it is only in limited release right now so I haven’t had a chance to use it yet,” Trattler said.

At the American Society of Cataract and Refractive Surgery meeting in San Diego, John A. Vukich, MD, presented 3-year results of a clinical trial that included emmetropic presbyopes implanted with the Kamra inlay. The primary effectiveness target of 75% of eyes achieving uncorrected near visual acuity or better was met and exceeded at all scheduled visits from 1 month to 36 months postoperatively.

“One of the particularly exciting things about the Kamra inlay is that it maintains and restores a full depth of focus. So, it’s not a fixed-focus point like monovision,” Waring said. “Not only do you have improvement in uncorrected near vision, but you maintain your uncorrected distance vision and get improvement in uncorrected intermediate vision and everywhere in between. So, it’s a true through-focus based on the optics of a small aperture. It’s like the f-stop of a camera.”

Other corneal inlays

Other inlays in the development pipeline include the Raindrop (ReVision Optics), Flexivue Microlens (Presbia) and Icolens (Neoptics). The Raindrop and Flexivue are undergoing FDA review.

“They all have different features that will make them unique from each other and will be able to allow the surgeon a choice in which inlay may serve their patients better,” Hoopes said.

The Raindrop, a hydrogel disc, is implanted under a LASIK flap.

The Flexivue, which is placed in a femtosecond corneal pocket, has a diameter of 3 mm and is made of a hydrophilic polymer.

The Icolens, a 3-mm hydrogel implant, has an edge thickness of 15 µm or less and a central hole of 150 µm to facilitate nutrient flow. The Icolens system includes a microlens, femtosecond pocket-cutting algorithm and preloaded deployment device. The Icolens received CE certification in the European Union in 2013.

“The Raindrop and Flexivue inlays show promise, and I am looking forward to seeing their FDA phase 3 results,” Trattler said.

“It’s difficult because we don’t have access to patients to see which corneal inlays perform the best and which ones have the highest visual quality, least side effects and things like that. At this point, it’s still early. Right now, they’re all very promising. The early data from Raindrop and Presbia suggest that these inlays deliver a nice range of vision while still maintaining good binocularity,” he said.

Jon Dishler, MD, FACS, and Stephen G. Slade, MD, OSN Refractive Surgery Board Member, performed a number of Raindrop inlay implantations as investigators in two clinical trials.

“I think it’s a great concept in that it’s a biocompatible material. It has the same refractive index as the cornea,” Dishler said. “It basically creates this small plus power in the center of the cornea and creates asphericity where, when the pupil is small, patients looking at near things really do get better near vision, which is the plus. The minuses, it does have some impact on distance vision but not that much. It maybe knocks the distance vision down perhaps a line, on average, maybe 20/20 to 20/25 or something like that. So, there’s more of a gain in near vision than a loss of distance vision.”

Dishler noted that, like the Kamra inlay, the Raindrop is placed in one eye, which presents challenges for some patients.

“Just like monovision, one of the limitations of it is that not everyone adapts well to a monovision-type approach where only one eye is for reading. It gives a little help for reading,” he said.

Dishler said that, theoretically, the Raindrop inlay could be used off label as an adjunct to LASIK.

“In the studies for the Raindrop, we made a flap very similar to what you do in LASIK,” Dishler said. “If somebody was already having a LASIK procedure and was a presbyope, they could, theoretically, have their distance vision corrected with LASIK and in one eye put the inlay in so that they would have this kind of modified monovision. Then, if they liked it, that would be great, and if for some reason they didn’t, it’s actually pretty easy to remove these things. Then, they would be back to just the full LASIK correction.”

In addition, the Raindrop inlay works well in low hyperopes, Dishler said.

“It turns out that a lot of people who think that they’re emmetropes, who think they have no refractive error, actually are low hyperopes. A lot of people are very slightly farsighted. I don’t know the exact percentages, but it might be as high as 30% of the population,” he said. “Those people are the ones that are annoyed by presbyopic symptoms the earliest, at 39, 40, early 40s. They have problems with reading. In that group, the lens does particularly well.”

Theoretically, the Raindrop could be implanted bilaterally in low hyperopes, Dishler said.

“Potentially, and this is something that would have to be investigated in another study, that group could theoretically have the inlay put in both eyes because they would be able to retain their distance 20/20 vision but also be able to gain a lot of near vision. They get all gain and really no downside other than the inherent risks of the procedure itself,” he said.

Overall, corneal inlays are not ideal for all patients, Hovanesian said.

“All of these inlays are not as trivial as doing monovision or as doing LASIK,” he said. “You’ve got a device you’re putting in the cornea, and not all eyes tolerate them extremely well. In most of these trials, there is about a 10% rate of explants. These are patients who need careful follow-up, more so than LASIK. That’s a little bit of a weakness of the inlay technologies but one that I think we should be shedding light on rather than trying to downplay.”

Although corneal inlays are gaining ground, monovision LASIK and PRK will continue to play a key role in presbyopia correction, Hoopes said.

“I think the inlays will quickly gain popularity, and they’ll begin to have a major place in our treatment arms for presbyopia,” he said. “With that said, monovision, as provided with LASIK or PRK, will still always be an important tool, and it won’t be something that’s eliminated just with these new inlay surgeries.”

Scleral implant

Another device is the VisAbility Implant System (Refocus Group), a scleral implant.

“Implants are placed in the sclera, and patients obtain increased range of vision. They’re basically PMMA inserts (called VisAbility) placed into the sclera to expand the sclera, which allows the zonules to function better. The VisAbility Implant System is currently approved in the European Union, where over 90% of patients have achieved J3 (20/30) at 6 months. Currently, Refocus has an FDA clinical trial underway in the U.S. It appears that this technology is working quite nicely,” Trattler said.

Multifocal and accommodating IOLs

Matossian said there are risks associated with laser cornea-based methods of presbyopia correction.

“With the cornea-based approaches, depending on the type of approach, patients may end up with post-surgical exacerbation of their dry eyes,” Matossian said. “Even people who have moderate dry eye, if they don’t have their ocular surface optimized prior to the LASIK and do not maintain their therapeutic regimen after their LASIK, they may end up with suboptimal visual outcomes.”

Advancing diagnostic tools and technology may enable surgeons to obtain refractive outcomes with IOLs that approach those of laser-based methods, Matossian said.

“We now have better implant options and a larger selection of implant choices. We have more accurate formulas for IOL calculations, and we have better diagnostic tools, including intraoperative aberrometry like ORA (Alcon),” she said.

Matossian noted the benefits of the newest iteration of the Tecnis multifocal IOL (Abbott Medical Optics) with +2.75 D and +3.25 D of near adds.

“You can titrate the amount of add to best match the patient’s specific needs between the three options: the +2.75 D, the +3.25 D or the original +4.00 D. That’s one way I treat presbyopia,” Matossian said.

The Crystalens and Trulign toric IOLs (both Bausch + Lomb) are also good choices, she said.

“But I am very clear with my patients that they will most likely need over-the-counter reading glasses for near tasks,” she said.

Hovanesian said the Crystalens may not provide enough accommodation to satisfy some patients, unless blended vision is also incorporated into the treatment. In addition, neural adaptation to multifocality is difficult for many patients, he added. – by Matt Hasson

• References:
• Ayoubi M, et al. J Cataract Refract Surg. 2010;doi:10.1016/j.jcrs.2009.12.035.
• Corpuz C, et al. J Cataract Refract Surg. 2015;doi:10.1016/j.jcrs.2014.03.035.
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• Garza EB, et al. J Refract Surg. 2013;doi:10.3928/1081597X-20130129-01.
• Huseynova T, et al. J Refract Surg. 2014;doi:10.3928/1081597X-20140120-06.
• Menassa N, at al. J Cataract Refract Surg. 2012;doi:10.1016/j.jcrs.2011.11.051.
• Ryan A. et al. J Cataract Refract Surg. 2012;doi:10.1016/j.jcrs.2013.03.016.
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• For more information:
• Jon Dishler, MD, FACS, can be reached at Dishler Laser Institute, 8400 E. Prenctice Ave., Suite 1200, Greenwood Village, CO 80111; email: jond@dishler.com.
• Phillip C. Hoopes Jr., MD, can be reached at Hoopes Vision, 11820 State St., Draper, UT 84020; email: pchj@hoopesvision.com.
• John A. Hovanesian, MD, FACS, can be reached at Harvard Eye Associates, 24401 Calle De La Louisa, Suite 300, Laguna Hills, CA 92653; email: drhovanesian@harvardeye.com.
• Cynthia Matossian, MD, can be reached at Matossian Eye Associates; email: cmatossian@matossianeye.com.
• William B. Trattler, MD, can be reached at 8940 N. Kendall Drive, #400, Miami, FL 33176; email: wtrattler@gmail.com.
• George O. Waring IV, MD, can be reached at Medical University of South Carolina Storm Eye Institute, 167 Ashley Ave., Charleston, SC 29425; email: georgewaringiv@gmail.com.

Disclosures: Dishler reports he was an investigator for and holds limited stock options from ReVision Optics, and is an active investigator in the SMILE study and a consultant for Carl Zeiss Meditec. Hoopes reports he is a consultant to Abbott Medical Optics and a shareholder with AcuFocus. Hovanesian reports he is a consultant to Abbott Medical Optics, Alcon, Bausch + Lomb and ReVision Optics. Matossian reports she is a consultant for Abbott Medical Optics and a speaker for Bausch + Lomb and Lenstec. Trattler reports he receives travel support from Refocus and is a consultant to Abbott Medical Optics. Waring reports he is a consultant for AcuFocus.

If approved in the US, will presbyLASIK become the preferred method of presbyopia correction over monovision?

PresbyLASIK safer, more accurate than monovision

PresbyLASIK has multiple advantages over monovision. I have no doubt that with time, experience and nomograms, presbyLASIK will become the preferred method for correcting presbyopia in the so-called young presbyopes between the ages of 40 and 55 years. Multifocal LASIK produces better contrast sensitivity and better depth of focus than monovision. It is better tolerated by people because both eyes see at distance and near, especially in those patients with demanding jobs such as drivers and surgeons. As one eye takes all the correction for near, the eye dedicated to distance vision usually stops accommodating, something that makes this type of correction of short duration. That does not happen with presbyLASIK, a more durable procedure. Finally, with monovision surgery, there is no guarantee that the refractive difference between the eyes will be enough to produce vision at all distances. The number of re-treatments is higher than normal regular laser surgery and higher than presbyLASIK. Finally, both procedures are safe and completely reversible.

Monovision in my own practice is tolerated only by 4% to 5% of those patients who receive the contact lens trial either for monovision or corneal inlays.

No doubt, monovision will be replaced by presbyLASIK in case of U.S. approval by the FDA.

Gustavo F. Tamayo, MD, is an OSN Latin America Edition Board Member. Disclosure: Tamayo reports he is a member of the boards of Presbia and Abbott Medical Optics and holds a patent for presbyLASIK software.

Monovision offers better contrast sensitivity

When refractive surgeons are polled, monovision (or modified monovision) is the preferred option of refractive surgeons in every meeting polled for decades when compared with multifocal IOLs, contact lenses and LASIK.

The biggest problem even with good screening and education in premium IOL or LASIK surgery is preselecting patients who will be successful with presbyopic correction. It is hard to predict which patients will be happy.

Charlie Kelman once said to the FDA panel in 1986, ”Never put in an implant design you can’t remove.” Refractive surgeons also need an exit strategy to make our patients happy, and presbyLASIK typically does not offer this option. LASIK monovision does. Monovision offers an option for better contrast sensitivity than presbyLASIK, particularly for night driving if a thin pair of glasses are used under poor contrast conditions. PresbyLASIK does not.

In summary, as of 2015, monovision or modified monovision LASIK is preferred because of better optics, visual performance, its reversibility and its acceptance by experts in refractive surgery.

Scott M. MacRae, MD, is an OSN Optics Board Member. Disclosure: MacRae reports he is a consultant for Bausch + Lomb.