Keratoconus

Keratoconus is an eye condition where the normally round-shaped cornea progressively thins, causing a cone-like bulge to develop. The cornea is the clear window of the eye and is responsible for focusing the light entering the eye. Therefore, distortion of the corneal shape can significantly impact everyday vision. It usually affects both eyes, but one may be more severely impacted. 

It has been estimated to occur in 1 out of every 2,000 persons in the general population and can affect men and women alike. The cause of the disease is still being investigated. Genetics, allergies and other environmental factors may contribute to its onset and severity.

Keratoconus is generally first diagnosed in the late teens or early 20s, with symptoms of blurry vision with glasses, frequent glasses prescription changes, and high astigmatism. The severity of keratoconus can vary greatly, with some patients requiring only a simple glasses prescription while others can only see with special, rigid gas permeable contact lenses. 

Treatment

Intacs

Intacs corneal inserts or implants are a less invasive surgical option used for correcting bulging or irregularity of the cornea, the front window of the eye. Intacs were originally approved by the FDA in 1999 to treat mild nearsightedness (myopia). However, Intacs are now primarily used to reshape bulging, thin, and/or irregular corneas. Intacs (Addition Technologies, Des Plaines, IL) are thin, clear half-rings or semicircular segments of plastic that can be inserted into the cornea to provide support for the cornea and help make its shape more circular (instead of oval).

In 2004, the FDA granted Intacs a Humanitarian Device Exemption (HDE) to allow for surgical treatment of keratoconus. Keratoconus is a condition where the collagen in the cornea is weaker, so that the shape of the cornea changes and bulges. This approval allows Intacs to be marketed for reduction or elimination of nearsightedness and astigmatism in keratoconus patients where functional vision is no longer obtained with glasses or contact lenses.

For keratoconus patients who are contact lens intolerant, Intacs provide a new option to improve both corrected and uncorrected vision, and may defer the need for a corneal transplant. Laser vision correction, such as LASIK, is usually not an option in keratoconus because sculpting and removing tissue with the excimer laser would further thin and weaken an already weakened cornea.

Intacs procedures are performed by fellowship-trained corneal surgeons, such as the cornea specialists at Pepose Vision Institute.

Frequently Asked Questions

How do Intacs work?
For keratoconus, Intacs work by flattening the steep part of the cornea or cone to reduce vision distortions.
Intacs are made of the same material (polymethyl methacrylate or PMMA) used in cataract lens implants for decades.  The semicircular segments come in different thicknesses, with thicker Intacs creating more flattening.

Are you a candidate for Intacs?
You may be eligible for Intacs if you:

  • Are 21 years of age or older
  • Have keratoconus, pellucid marginalis, or other conditions marked by corneal bulging and thinning
  • Have unstable vision or an irregular corneal shape after LASIK
  • Have visual distortion even with glasses or contact lenses
  • Are unable to wear your contacts comfortably

Patients with central corneal scarring or extremely thin and steep corneas may not be eligible for Intacs.  Corneal transplant procedures may be considered for these very advanced keratoconus patients.

What is involved in the Intacs procedure?
Intacs surgery is a same-day, out-patient procedure.  The first step of Intacs insertion is applying antibiotic and anesthetic drops to the surface of the eye.  Patients also usually receive oral sedation, so that a driver is needed after the procedure.
A lid holder is applied to prevent blinking during the procedure, which is performed under an operating microscope while the patient is lying flat on the back.
An advanced laser (iFS femtosecond laser) is used to create a 360 degree ring-like tunnel or channel at approximately 70% - 80% depth of the cornea.  The tunnel is approximately 3.5 mm away from the center of the cornea, so that most patients do not actually see the Intacs implants in their vision. 
  
Pepose Vision Institute surgeons are proud to be the FIRST and ONLY corneal specialists in the Bi-State region to utilize a bladeless technique to create Intacs channels.

Intacs
Corneal Implants

Following creation of the channels, one or two half-ring Intacs segments are inserted into the channel.  The segments come in different thickness, such that the Intacs size can be customized based upon the shape of the individual cornea.

What happens after the procedure?
Following the procedure, the patient is advised to rest overnight.  Antibiotic, anti-inflammatory, and artificial tear drops are used for several days or weeks.  There is some fluctuation in the vision and some mild eye irritation.  However, you do not feel the Intacs because they are below the skin of the cornea.
Usually, the vision will improve within a few days but full healing can take over 3 months.  Some patients may start wearing temporary soft contact lenses to improve their vision during the corneal healing phase.  A final glasses or contact lens prescription will be measured 3 – 6 months after the procedure.
Results of Intacs will depend on the degree of keratoconus or corneal irregularity in each individual.  However, Intacs may not halt progressive bulging and steepening of the cornea from keratoconus or similar corneal diseases.  Clinical studies of investigational procedure such as corneal cross-linking to stiffen the corneal collagen and prevent bulging are underway.  Intacs patients may be candidates for future cross-linking procedures.

Are Intacs reversible?
Intacs are designed for long-term vision correction, but are reversible.  Intacs may not sufficiently improve the vision in about 5% of patients.  In these cases, Intacs can be surgically removed from cornea or can be replaced with different size ring segments.  If Intacs are permanently removed, the vision will likely return to the way it was prior to surgery after a few months.  Following removal, Intacs usually do not leave behind scar tissue, although this possible.

What are potential complications of the Intacs procedure?
As with any surgery, infection of the corneal tissue surrounding the segments or the insertion incision site is possible.  Usually this would occur within the first few weeks of the surgery and can be treated with antibiotic drops or with removal of the segments.  For this reason, antibiotic drops are applied prior to the surgery and for several days afterwards.  It is possible for the Intacs implants to shift from their original position, in which case they may be repositioned or permanently removed.  It is also possible for the corneal tissue overlying the implants to thin, in which case the implants may require removal.
During the surgery, it is possible for the tunnel or channel for the implants to be too deep or too shallow within the substance of the cornea, such that implant insertion is not possible.  It is also possible for perforation of the corneal tissue to occur during insertion of the Intacs segments.
Some patients experience visual symptoms including difficulty with night vision, glare, halos, blurry and fluctuating vision.

What are the advantages of the Intacs procedure as compared to a corneal transplant?
corneal transplant vs intacsA corneal transplant involves replacing either a portion of the cornea or of the entire central cornea with corneal donor tissue.  As it is a more invasive surgery, its complications can be much more severe.  It typically requires a long recovery period of several months to a year.
The Intacs procedure does not require removal of corneal tissue, but rather reshapes the weakened cornea by adding mechanical support to it.  The recovery period is typically shorter, with more rapid improvement in vision.  The synthetic material of Intacs is not at risk for rejection the way donor transplant tissue is.
In some cases, if Intacs are not effective, patients can proceed with corneal transplantation

Your eye doctor is the best person to consult with regarding whether this new and exciting option for treating keratoconus is right for you. Contact Us Today!.