THE WORLD of refractive surgery has been expanding as of late. Options have been added for managing myopia and hyperopia, via LASIK, PRK, meanwhile presbyopia correction has seen rapid growth as well, presenting alternatives to glasses and contact lenses for this population via intraocular options.
As optometrists, we must be aware of all the options available to our patients and for whom each is best suited, so that we can discuss with our patients the most effective and appropriate treatments. Here, I discuss these new options and how to identify surgical candidates and provide patient education.
REFRACTIVE SURGERY OPTIONS
Two refractive surgery options have expanded the offerings for patients.
- Contoura Vision (Alcon). The topography-guided LASIK treatment is based on patients’ corneal topography. Specifically, the cornea is treated for irregularities to gain ideal corneal shape and curvature. Contoura is FDA approved to provide correction for up to -14.00D myopia, hyperopia of up to 6.00D and mixed astigmatism of up to 6.00D, according to the company. A total of 92.6% of eyes treated gained 20/20 vision or better, and 34.4% achieved 20/12.5 or better within 12 months after surgery, according to FDA documents about Contoura’s clinical trial. Further, Contoura reduces higher-order aberrations, as well as visual symptoms, such as glare and difficulty driving at night, side effects often associated with LASIK, according to Clinical Ophthalmology. Possible risks associated with Contoura, as with LASIK vision correction surgery: dry eye disease (DED), diffuse lamellar keratitis, corneal edema, miscreated flap, corneal haze and corneal epithelial ingrowth.
- ReLEx SMILE (ZEISS). FDA approved in September 2016, ReLEx SMILE (Small Incision Lenticule Extraction) is laser vision correction for myopia and astigmatism only. Specifically, using a femtosecond laser, a lenticule or disc of tissue, is created inside the intact cornea. This lack of flap allows for the nerve tracts of the upper corneal layer to stay mostly intact with a decrease in surgically induced DED. Multiple studies comparing traditional LASIK to SMILE patients have shown a consistent decrease in SMILE patients post-operative DED and an increase in corneal sensitivity. These studies include those in Ophthalmology, Journal of Refractive Surgery and Graefe’s Archive for Clinical and Experimental Ophthalmology. The company states it has a treatment range of -1.00D to -8.00D, with <-0.50D cylinder and a manifest refraction spherical equivalent (MRSE) of -8.25D. Monovision could be an option with SMILE for a myopic presbyopic patient who has been successful with previous contact lens monovision. However, at this time this is not yet an option for hyperopic or emmetropic presbyopes. This is because SMILE currently works by flattening the center of the cornea to reduce myopia. Possible applications for hyperopia are under current investigation. Most adverse effects with SMILE are complications related to surgeon inexperience including: suction loss, cap rupture, lenticule rupture, black spots, bubbles in the interface and lenticule misdissection or incomplete extraction. Other possible complications are similar to that of LASIK, such as diffuse lamellar keratitis, corneal edema, interface infiltrates, ghost images, haze and epithelial ingrowth. It is also worth noting that enhancement surgery using the same SMILE method may not be possible as it is not repeatable and would require either PRK or LASIK.
CORNEAL INLAY OPTIONS
Currently, two categories of corneal inlays are available to treat presbyopia, with a third in development. (See: “Flexivue Microlens Refractive Corneal Inlay,” p.22.)
- Raindrop Near Vision Corneal Reshaping Inlay. FDA approved in 2016 for the treatment of presbyopia, Raindrop (ReVision Optics) is a 2mm in diameter, 32μm center thickness hydrogel space-occupying lenticule implanted under a corneal flap to reshape the cornea. Specifically, by increasing the central anterior corneal curvature, a hyperprolate cornea is created, allowing for a pseudo-accommodative state that improves both near and intermediate vision, according to information submitted to the FDA. The pseudo-accommodation is enhanced with pupil constriction. The inlay is indicated for use in the non-dominant eye of presbyopic patients aged 41 to 65 whose MRSE is +1.00D to -0.50D with <0.75D cylinder and have a near add correction of +1.50D to +2.50. Of 340 patients, 93% had uncorrected near visual acuity (UNVA) in the surgical eye of 20/25 or better, and 97% had uncorrected intermediate vision of 20/32 or better, according to a one-year study published in Ophthalmology. During the study, 27 inlays were removed; 10 because patients were dissatisfied with their visual outcome at 3 months, 10 because of complaints of haze, two from inlay decentration, three requested removal and two had epithelial ingrowth.
- Kamra Small Aperture Inlay (AcuFocus). FDA approved in 2015, Kamra (AcuFocus) is a small aperture inlay (3.8mm outside diameter and 1.6mm inside diameter) made of polyvinylidene fluoride that’s used in the treatment of presbyopia. The device is implanted within the cornea in a femtosecond laser-created pocket, according to information submitted to the FDA. The device is an opaque annulus, creating a pinhole effect by reducing the aperture of the eye. This improves near vision by increasing the depth of focus. The inlay is indicated for use in the non-dominant eye of presbyopic patients between the ages of 45 and 60. The ideal patient has a MRSE of +0.50D to -0.75D with >0.75 cylinder, and a near correction of +1.00D to +2.50D, also according to FDA documents. Of 389 patents, 83.5% had UNVAs of 20/40 or better, and 46.2% had UNVAs of 20/25 of better after 12 months, according to FDA documents. During this same study 44 (8.7%) of patients had the inlays removed at 36 months. Of those removed, 4.4% were because of visible appearance, 8.9% for medical indication and 86.7% because of visual complaints.
IDENTIFYING SURGICAL CANDIDATES
Remember that with all refractive surgeries and corneal inlays, patients must be older than age 18, and their vision must be stable before you can send them to a surgeon for a consult.
To determine visual stability and eligibility, perform a comprehensive exam to identify any underlying problems that could result in a poor visual outcome or disqualify the patient. Contraindications for LASIK and inlays include: corneal dystrophies, keratoconus, acute eye disease, history of ocular inflammation or history of herpetic eye disease, autoimmune diseases and macular scarring or disease, such as AMD, uncontrolled glaucoma or diabetic retinopathy. Patients who have had previous corneal LASIK and PRK may still be candidates, depending on corneal thickness. With the RainDrop a central corneal thickness of at least 500µm is needed, while Kamra requires a minimum depth of 200µm for the lamellar pocket and a minimum of 250µm of residual posterior stromal bed thickness.
Treating pre-existing ocular surface disease is a must before referring patients to surgeons, and for surgeons before they can obtain optimized measurements. During your discussion with patients regarding their options, it is best to bring this up and begin aggressive treatment.
If a patient is an early presbyope, who may be best suited for monovision, it is a good idea to do a contact lens trial prior to sending him or her for a consult. Doing so can help significantly decrease future chair time.
Finally, with inlays it is important to identify the non-dominant eye, since most are placed within the non-dominant eye, according to documents submitted to the FDA.
Refractive Corneal Inlay
Although not yet FDA approved, the Flexivue Microlens (Presbia) has been in use in other countries since it was CE-certified in 2009, according to the company. Made from a hydrophilic acrylic material, with a lens design similar to a bifocal, the clear lens is 3.2mm in diameter and has add powers ranging from +1.50D to +3.50D in 0.25D increments. Similar to the Kamra, an intrastromal pocket is made with a femtosecond laser.
A total of 75% of 47 patients’ UNVA was 20/32 or better 12 months after implantation, according to a prospective study by Limnopoulou et al.
Currently, 421 participants are enrolled in the U.S. trials, with potential data submission to the FDA in late 2017, according to ClinicalTrials.gov .
PROVIDING PATIENT EDUCATION
Should the patient be a viable candidate, I suggest using the following script, for example: “There are an increasing array of options for you. Presbyopia does not have to mean a life sentence of contact lenses or a drawer full of readers, though those are completely reliable and viable options as well.”
Then, review the options based on the needs of your patients. Evaluate these needs by asking questions to ascertain what outcomes your patient would like to see:
- Does the patient want to be free of glasses?
- Does he or she find contact lenses irritating?
- Is your patient an early presbyope who would still like to have his or her vision corrected, but thinks he or she is too old for LASIK?
Within this discussion, it’s also important to set expectations:
- How quickly should the patient expect his or her vision to be at its maximum?
- What are the common visual side effects of post-refractive surgeries and corneal inlays?
- Does the patient know his near vision will continue to change through time until the process is complete?
All these questions should be answered prior to the surgical consult and surgery.
Newer LASIK techniques and corneal inlays have the potential to be game changers. Educating ourselves on what is available, who is best suited for these procedures and educating our patients about what they can expect post-surgery is important in moving forward. OM