Article

Advancements in presbyopia treatment

The latest surgical options to help patients avoid “cheaters.”

How many times have you heard a presbyopic patient ask, “Is there anything you can do about those darn ‘cheaters?’” Many doctors and companies have long sought ways to conquer presbyopia, or the loss of near accommodation, which eluded us until the last 10-15 years. Several companies have developed products and procedures via clinical research that provide us with solutions.

Through the years, three theories on what causes presbyopia have been largely accepted:

  1. As we age, the crystalline lens stiffens and therefore does not as easily change shape to focus light.
  2. The zonules and ciliary body lose their contractability.
  3. The lens grows, crowding the space and releasing tension on the zonules, similar to a saggy trampoline.

Whatever the cause (perhaps a combination of all three), presbyopia continues to trouble our aging patient population. Patients struggle with focusing on near tasks, such as reading books and reading their cell phones. They may develop frequent headaches as they try to focus for work and leisure. They struggle with a delay in focusing when transitioning from looking down the road to looking at their speedometer. Most of all, they have become annoyed with needing multiple pairs of readers in every room and vehicle.

Here are some of the most recent presbyopia treatment options.

Monovision

For patients in their 40s and 50s who want to eliminate the need for reading glasses, whether or not they have had previous LASIK, we traditionally would have offered some form of monovision — first in contact lenses then perhaps in some form of refractive surgery, such as LASIK or PRK. With monovision, one eye is corrected for near vision, while the other eye is corrected for distance. Monovision LASIK or PRK can benefit some, but we must educate the patient on potential drawbacks, such as patient intolerance to distance blur in the near eye, along with glare and halos.

Refractive lens exchange

Refractive lens exchange is an option for some patients who want a permanent correction that avoids the need for cataract surgery later in life. In this procedure, the natural lens is removed in the same manner as in cataract surgery and replaced with an IOL just as with cataract surgery.

With this procedure, we must educate patients on the different types of lenses available to them. With a monofocal lens, the surgeon chooses a different power for each eye to create monovision. Multifocal, diffractive, and accommodating IOLs can expand a patient’s range of focus without inducing monovision. It is important that we counsel patients on the potential for lens dysphotopsia prior to consideration of multifocal or diffractive IOL use. Additionally, a surgeon may choose to customize the refractive target of an eye to help increase the range of focus with these IOLs.

Corneal inlays

Corneal inlays provide patients with near-vision correction options with minimal compromise to distance vision. Patients maintain stereoacuity with both inlays at distance vision while obtaining a near-vision benefit.1,2 Patients experience a period of neuroadaptation after inlay implantation, so visual recovery can take months. The most common symptom following inlay implantation is ocular surface dryness.1,2 Reinforcement of both good lighting and lubrication at every postoperative examination aids with patient compliance and success with the technology. Typically, patients with corneal inlay technology take postoperative anti-inflammatory medications for three months or longer. Corneal clarity is monitored closely after implantation with Pentacam (Oculus) densitometry and placido disc topography due to risk of corneal haze development.

The KAMRA (AcuFocus) and Raindrop (ReVision Optics) inlays are removable, which is an attractive feature for both patient and surgeon. Although the explantation rate is low, the two most common reasons for corneal inlay removal are patient dissatisfaction and persistent corneal haze.1,3,4 After explantation, typically patients achieve 20/25 corrected distance visual acuity or better.4 Visual recovery can take six months or longer.1,3,4

KAMRA

In April 2015, the FDA approved the KAMRA inlay for patients ages 45 to 60 who cannot focus clearly on near objects but do not need corrective lenses for clear distance vision.5 The KAMRA inlay is a 3.8-mm diameter black disc with a central 1.6-mm aperture, which improves depth of focus by creating a pinhole effect in a patient’s non-dominant eye (Figure 1).5 This inlay is implanted into an intrastromal pocket created by a femtosecond laser at an average depth of 250 μm. Its 8,400 microperforations allow nutrients to permeate.

Figure 1. Slit lamp image of a KAMRA inlay (left) one week post-operatively.
IMAGE COURTESY JESSICA HECKMAN, OD

Preoperative refraction has been shown to be an important factor in the resultant uncorrected distance visual acuity as well as uncorrected near visual acuity for a patient after inlay implantation.2 A manifest refraction spherical equivalent (MRSE) of -0.75 D in the surgical eye has been shown to provide optimal results at both distance and near.6 A KAMRA inlay procedure can be combined with both LASIK and PRK, sequentially or simultaneously to optimize patient MRSE for the KAMRA inlay. Often a pinhole occluder will be used to simulate vision for a patient considering KAMRA implantation.

Raindrop

The Raindrop Near Vision Inlay received FDA approval in June 2016 for patients ages 41 to 65 years old. The Raindrop is a clear, 2.00 mm small-diameter inlay made of hydrogel (Figure 2). The hydrogel material allows for the free flow of nutrients to the cornea. The FDA-approved technique calls for the surgeon to implant the inlay under a flap made with a femtosecond laser in the non-dominant eye.

Figure 2. Slit lamp image of a Raindrop inlay (below) one week post-operatively.
IMAGE COURTESY NIC JACOBS, COA

This inlay works differently than the KAMRA inlay — it creates a profocal shape to the cornea. This central steepening of the cornea allows for increased focusing power at near. The ideal preoperative MRSE for a patient considering Raindrop implantation is plano to +0.50D.1 This procedure can also be performed off-label simultaneously, with LASIK done with a deeper flap, up to 34% of corneal thickness.1 A soft multifocal contact lens can help simulate vision for a patient considering surgery with a Raindrop inlay.

Conclusion

With these and other technologies still in development, it is an exciting time in ophthalmology. With an expanding toolbox of presbyopia solutions, it is very important to educate patients on all the options and to match the technology with their personal vision needs. Our patients will do their homework on their options, but we also need to do ours so that we can help guide them to the best option for them. OP

REFERENCES:

  1. Whitman J, Daugherty PJ, Parkhurst GD, et al. Treatment of presbyopia in emmetropes using a shape-changing corneal inlay: one-year clinical outcomes. Ophthalmol. 2016;123:466-475.
  2. Seyeddain O, Hohensinn M, Riha W, et al. Small-aperture corneal inlay for the correction of presbyopia: 3-year follow-up. J Cataract Refract Surg. 2012;38:35-45.
  3. Yilmaz OF, Alagoz N, Pekel G, et al. Intracorneal inlay to correct presbyopia: long-term results. J Cataract Refract Surg. 2011;37:1275-1281.
  4. Ali├│ JL, Abbouda A, Haseynli S, et al. Removability of a small aperture intracorneal inlay for presbyopia correction. J Refract Surg. 2013;29:550-556.
  5. Koury CB. Inlay to treat presbyopia gets US approval. Cataract and Refractive Surgery Today. 2015;15.61-63.
  6. Steinert RF, Schwiegerling J, Lang A, et al. Range of refractive independence and mechanism of action of a corneal shape-changing hydrogel inlay: results and theory. J Cataract Refract Surg. 2015;41:1568-1579.