Treatments to Correct Reading Vision are at Hand

A future with clear vision?

Presbytes, there’s hope; inlays are almost in reach for US patients.

BY MARTIN L. FOX, MD

Since time immemorial men and women have struggled with the often-sudden onset of losing their ability to see closely. It was Aristotle who termed afflicted individuals as presbytes, coining for the ages the term that describes the condition of the aging eye. In man’s early years, having wealth was some help: Romans designated literate slaves to read for them. In the search for a solution innovation was pivotal: Ben Franklin figured out the aging eye couldn’t quite focus like it used to, and invented the bifocal.

Presbyopia affects more than 25% of the world population, claiming more than 1 billion new presbytes annually. It is a condition that virtually all primates face in their fourth or fifth decade.1 So, the pursuit of a solution for this most universal of human afflictions has become a passion for some refractive surgeons and those in related industry. The search has led to a litany of procedures, many of which have fallen far short on safety and efficacy metrics.

The search could end sooner than later. In August, an FDA panel decided the benefits of the KAMRA (AcuFocus Irvine, Calif.) inlay outweighed the “risks for patients suffering vision loss” because of presbyopia,2 pushing it along the approval process. The KAMRA is marketed in 33 countries; the company’s website says 20,000 inlays have been implanted outside of the United States. We may be on the verge of witnessing the birth of a new surgical subspecialty devoted to presbyopia’s effective correction.

Sacrifices and reversibility

Until now, the conventional approach to presbyopia in LASIK and PRK has been limited to monovision or blended vision in which the non-dominant eye is targeted for a myopic goal to allow for midrange near-vision. With a well-motivated patient this approach has provided for reasonable function; however, it does sacrifice distance clarity for a small amount of intermediate vision. Reversibility is a key component of this approach.3

Prior to the advent of corneal inlay technology, attempts at presbyopia correction have included two excimer laser PresbyLasik procedures(4,5,6); an intrastromal femtosecond laser treatment (IntraCor, Technolas Perfect Vision, Munich, Germany); and two procedures involving expansion of the circumlental space through scleral modification (LaserACE System, ACE Vision Group) and PresView scleral implant (Refocus Group).

While PresbyLasik investigators reported success using central reading and peripheral reading zone excimer techniques, these multifocal laser ablations ultimately created higher order aberration and, consequently, quality of vision issues. Some patients have found it difficult to adapt to the compromise, and others were dissatisfied by the minor loss of distance vision.7 Despite this, multifocal excimer designers have not given up on this approach.

The intrastromal femtosecond (IntraCor) approach works via the concentric rings designed to create a multifocal cornea.8 Despite favorable outcomes, researchers also have noted a loss of up to two lines of best-corrected vision in 7.1% of eyes; reversibility of the effect and quality of vision remain issues.9,10

Scleral expansion procedures

While the LaserACE and PresView implant procedures have been demonstrated to produce credible clinical results, improvement in near-vision in both procedures remains, for the most part, transient and unpredictable for most study patients. Device modifications and trials continue; phase 3 clinical trials have begun for both.11,12,13

The path to clear vision has been anything but straight, but one that has served a purpose. Surgeons now realize the required procedural caveats for success. Jeff Machat, MD, and his associate, Sondra Black, OD, of Crystal Clear Vision in Toronto, who have been implanting KAMRA for the past two years, say those caveats are clear. Effective successful presbysurgery must be:

They view the KAMRA inlay as meeting all criteria. Their belief in KAMRA is so complete that both have had the inlay implanted into their own eyes.

Corneal presbyopia inlays

This implantable corneal inlay is perhaps the most exciting of the new technologies in the US presbyopia-correction market. Inlay development has required years to address requisite safety factors including sizing, biocompatibility, adequate permeability to allow nutrient distribution and appropriate depth in the cornea. Inlays may be implanted in smooth femtosecond laser created pockets or under LASIK flaps; they require femtosecond lasers to produce adequate bed smoothness.

Pocket techniques are viewed as superior in corneal inlay surgery as they allow for maintenance of structural integrity, avoid issues of flap striation and preserve corneal nerve health, allowing for quicker healing and visual recovery. The placement of inlays requires specialized, precise attention to centration and depth of placement. New technologies that can produce and confirm accurate inlay placement in this critical area are essential for successful surgery.

Small-aperture optics

KAMRA is novel in presbyopia treatment, making use of small-aperture optics producing an increase in depth of focus, thereby preserving distance acuity while improving near and intermediate visual function. At 5 microns thick, the KAMRA is 3.8 mm in diameter and annular in shape with a central 1.6-mm aperture that is designed for corneal pocket implantation at a depth of 200 microns concentric to the line of vision.

The inlay is made from a propriety polyvinylidene fluoride material with 8400 laser etched 5.5-11.5 micron micro perforations placed in a random array to assure permeability. Unlike other inlay technology, the KAMRA continuously compensates for the progression loss of accommodative amplitude by means of improvement of depth of focus with its small aperture optics.

Jeff Machat, MD, and his associate, Sondra Black, OD, of Crystal Clear Vision in Toronto.

Seyeddain et al14 confirmed two-year data on the KAMRA inlay implanted in 32 eyes and confirmed that 96.9% of patients read J3 or better in the implanted eye with mean binocular UCNA improvement from J6 preoperatively to J1 after 24 months. Mean binocular uncorrected intermediate visual acuity was 20/20 at 1 month and remained 20/20 throughout 24-month follow-up and mean UCDA of 20/20 in the implanted eye and 20/16 binocularly. Company results presented to the FDA showed that 87% of enrollees were able to see 20/40 or better at near at 36 months post-op with 54% seeing 20/25 or better and 29% at 20/20 following the same period of follow-up with good overall satisfaction and preservation of good distance acuity. Initial symptoms of glare and dryness were reported to diminish over the first 12 months of observation.15

Newer kids on the block

Beside KAMRA, three other corneal inlays are under investigation: Raindrop Inlay (Revision Optics), the Flexivue Microlens (Presbia) and Icolens (Neoptics AG).

The Raindrop is a permeable 2 mm clear biocompatible hydrogel that works as a space-occupying lens designed for placement under a LASIK flap at a depth of 120 to 130 microns in the nondominant eye. The lenticule improves near and intermediate vision by creating steepening surface curvature change resulting in a multifocal cornea.

The Flexivue Microlens and the most recent inlay entry Icolens16 are multifocal pocket inlays designed to produce corneal multifocality in the nondominant eye. Flexivue is recruiting participants for a Phase 3 trial.17

Treating the presbyopic patient

Providing the presbyopic patient with functional, safe and lasting vision could be a reality soon. That written, the process of creating successful outcomes will rely on careful selection of candidates, exquisitely performed surgery and a comprehensive approach towards management of patient expectations. Drs. Machat and Black say their success with the KAMRA inlay has come only with great attention to detail, an evolving learning curve and a comprehensive approach to postsurgical counseling and management. OM


REFERENCES

1. Care of the patient with presbyopia. Optometric clinical practice guideline. Accessed March 24, 2015. http://www.aoa.org/documents/optometrists/CP17.pdf

2. AcuFocus press release. June 9, 2014. Accessed March 24, 2014. http://www.acufocus.com/sites/default/files/AcuFocus_FDA_Panel%20Vote_Press%20Release%20-%20FINAL.pdf494–500.

3. Goldberg DB. Laser in situ Keratomielusis monovision. J Cataract Refract Surg. 2001; 27:1449-1455.

4. Alió JL, Amparo F, Ortiz D, et al. Corneal multifocality with excimer laser for presbyopia correction. Curr Opin Ophthalmol. 2009;20:264–271.

5. Cantú R, Rosales MA, Tepichín E, et al. Objective quality of vision in presbyopic and nonpresbyopic patients after pseudoaccommodative advanced surface ablation. J Refract Surg. 2005;21:S603–S605.

6. Pinelli R, Ortiz D, Simonetto A, et al. Correction of presbyopia in hyperopia with a center-distance, paracentral-near technique using the Technolas 217z platform. J Refract Surg. 2008;24:

7. Luger, M, Ewering T, Arba-Mosquera, S. 3-Month experience in presbyopic correction with bi-aspheric multifocal central presbyLASIK treatments for hyperopia and myopia with or without astigmatism. J Optom. 2012;05:9-23.

8. Ruiz, LA. Intrastromal correction of presbyopia using a femtosecond laser system. J Refrac Surg. 2009; 25:847-854.

9. Holzer MP, Mannsfeld A, Ehmer A, et al. Early outcomes of INTRACOR femtosecond laser treatment for presbyopia. J Refrac Surg. 2009; 10:855-861.

10. Holzer MP, Knorz MC, Tomalla M, et al. Intrastromal femtosecond laser presbyopia correction: One-year results of a multicenter study. J Refract Surg; 2012;28:3:182-188.

11. http://www.totaleye.org/treatment-of-presbyopia-with-scleral-implants/. Accessed March 25, 2015.

12. https://clinicaltrials.gov/ct2/results?term=PresView+Scleral+Implant+Refocus+Group&Search=Search. Accessed March 25, 2015

13. https://clinicaltrials.gov/ct2/show/NCT01491360?term=Laser+ACE&rank=3. Accessed March 25, 2015

14. Seyeddain O, Riha W, Hohensinn M, et al. Refractive surgical correction of presbyopia with the AcuFocus small aperture corneal inlay: two-year follow-up. J Refract Surg; 2010;26:707-715.

  1. http://www.fda.gov/downloads/AdvisoryCommittees/CommitteesMeetingMaterials/MedicalDevices/MedicalDevicesAdvisoryCommittee/OphthalmicDevicesPanel/UCM400439.pdf. Accessed March 25, 2015.

16. Pallikaris IG, Bouzoukis DI, Kymionis GD, et al. Visual outcomes and safety of a small diameter intrastromal refractive inlay for the corneal compensation of presbyopia. J Refract Surg. 2012;28:168–173.

17. https://clinicaltrials.gov/ct2/show/NCT02110472. Accessed March 26, 2015.

Author
Dr. Fox

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