Corneal Implants and Inlays KAMRA Inlays
Corneal inlays currently undergoing clinical trials such as KAMRA corneal inlays are designed to compensate for near vision problems caused by presbyopia.
Similar to Intacs surgery, corneal implant procedures do not remove corneal tissue like LASIK and other laser vision correction procedures.
Corneal implant and inlay surgery also is reversible: If your vision is not acceptable after the procedure, the lens or refractive device can be removed and your vision will return to pre-surgical levels. Or it can be replaced with another inlay for a better outcome.
Corneal Implants versus Intacs
Corneal implants and corneal inlays differ from Intacs and other intrastromal corneal ring segments (ICRS) in where they are placed within the cornea and the type of vision problem they are designed to correct.
Corneal implants and inlays are positioned in the central zone of the cornea, directly in front of the pupil, and current models are designed to correct presbyopia.
Intacs and other ICRS are positioned in the peripheral cornea, outside the pupillary zone. These devices are designed to correct mild myopia in healthy eyes and vision problems caused by a corneal disease called keratoconus.
Corneal Implant Surgery
Corneal implant surgery, like Presby-LASIK, is performed on an outpatient basis and takes only a few minutes. It requires only topical anesthesia and there is no discomfort. If you wish, your eye doctor can provide a mild sedative prior to the procedure to relax you.
Basically the steps involved in corneal implant surgery are:
- Numbing eye drops are applied to the eye undergoing the procedure.
- A small pocket or LASIK-style flap is created in the cornea, usually using a femtosecond laser.
- The corneal implant is inserted into the cornea and is positioned directly in front of the pupil to improve vision.
The corneal wound from corneal implant surgery typically self-seals and heals within a matter of days with no need for stitches.
Current corneal inlay procedures for presbyopia treatment usually are performed on one eye only, producing a modified monovision effect. The eye receiving the corneal implant experiences improved near vision, thereby reducing or eliminating the need for reading glasses.
Types of Corneal Implants and Inlays
Though no corneal implants or inlays have yet been approved by the FDA for use in the United States, a number of companies are conducting clinical trials of their devices.
Corneal implant surgeries are being performed outside the U.S. with encouraging results.
Corneal implants and inlays being studied include:
PresbyLens is a corneal implant being developed by ReVision Optics (Lake Forest, Calif.) for the correction of presbyopia. The very small (1.5 or 2.0 mm) refractive device is made of a clear hydrogel plastic material, much like those used for soft contact lenses.
The PresbyLens implant is placed in the center of the cornea under a corneal flap. It improves near vision by increasing the curvature of the central zone of the cornea, creating a multifocal surface similar to the design of some multifocal contact lenses.
Though near and intermediate vision is improved in the eye receiving the PresbyLens implant, distance vision in that eye is slightly reduced. But early clinical trials suggest most patients are very pleased with the results.
In a recent study of the PresbyLens corneal implant conducted in Mexico, near vision was improved in more than 95 percent of eyes receiving the implant, and more than half of the eyes could read newspaper-size print without reading glasses. Also, all eyes receiving the implant could see 20/25 or better in the distance.
The PresbyLens corneal inlay has received a CE mark and is approved for sale in Europe under the name Vue+. Revision Optics currently is pursuing FDA regulatory approval to market and sell PresbyLens to refractive surgeons in the United States.
The KAMRA corneal inlay is being jointly developed by Bausch & Lomb (Rochester, NY) and AcuFocus, Inc. (Irvine, Calif.). The device currently is in FDA clinical trials for the treatment of presbyopia.
Instead of changing the curvature of the central cornea, the AcuFocus intracorneal inlay improves near vision by creating a pinhole camera effect to increase depth of focus.
The opaque AcuFocus inlay has an outer diameter of 3.8 mm and a small circular opening in the center that is 1.6 mm in diameter. This small aperture increases depth of focus and theoretically can improve near vision to a degree equivalent to a moderately strong bifocal lens.
A potential advantage of the AcuFocus inlay is that it appears to preserve good distance vision while improving near vision.
In an ongoing European study, 57 patients who underwent the AcuFocus implantation procedure and completed a 12-month follow-up attained the equivalent of 20/20 near vision without reading glasses and also achieved a mean uncorrected distance vision of 20/20 in the treated eye.
Though the AcuFocus inlay is opaque, it is virtually undetectable, even in blue eyes, according to one investigator. The device is made of a lightweight biocompatible material and has 8,400 laser-etched microscopic openings to allow nutrients to pass through the device and preserve cornea health.
A combined LASIK and KAMRA procedure is being performed outside the United States to simultaneously correct refractive errors and presbyopia.
Flexivue Corneal Inlay
The Flexivue System is a corneal inlay to correct presbyopia being developed by Presbia Coöperatief U.A. (Amsterdam and Los Angeles). The Flexivue corneal implant is very similar to the PresbyLens inlay, but a bit larger (3.0 mm diameter).
The Flexivue inlay is inserted into a small pocket created in the central cornea with a femtosecond laser the same type of laser used to create the corneal flap in all-laser LASIK.
Corneal Implant Surgery Risks
As with any vision correction surgery, there are some risks associated with corneal implant and inlay surgery, including risks of infection and reduced vision.
Some patients may experience visual symptoms, including glare, halos, blurry or fluctuating vision and night vision problems. These symptoms may be temporary and may resolve over time without treatment, or additional surgery may be required.
Follow-up visits are needed after corneal implant surgery to monitor the healing process and evaluate visual outcomes. Even after a successful procedure, you still may need glasses for certain visual tasks.
If your vision is not acceptable after corneal implant surgery, in some cases removing the intracorneal inlay and replacing it with one of a different design or power may improve results.
Corneal implants and inlays can be permanently removed if desired, and it may be possible for you to have a different type of refractive surgery, such as LASIK or PRK, to improve your vision. Ask your refractive surgeon for details.
Corneal Implant Surgery Cost
Because corneal implants and corneal inlays are not yet FDA-approved for use in the United States, data regarding cost of these procedures are not available at this time.
It's likely the cost of corneal inlay surgery will be comparable with LASIK cost or PRK surgery cost.
When considering vision correction surgery, price should not be the only factor in your decision. But to make sure you are getting a good value, it is a good idea to get quotes for the cost of corneal implant or inlay surgery from at least two refractive surgeons in your area.
Also, be sure you understand what the quoted fee includes. Some doctors will bundle fees for all pre-operative and post-operative care as well as the surgery itself into a single comprehensive "global" fee, whereas other doctors may present "a la carte" pricing, where each service is priced separately.
Corneal implant surgery is considered an elective vision correction procedure, and therefore all associated costs typically are "out-of-pocket" and not covered by vision insurance or health insurance.
Many eye surgeons offer financing plans for vision correction procedures to enable you to pay for your surgery over time. But make sure you fully understand all fees, interest rates and penalties associated with these plans before enrolling.
Note: This information is for general education purposes only. It is not to be used as a substitute for medical advice from your eye doctor or refractive surgeon.