INTACS, or intra-corneal rings, improves vision through corneal correction

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Intra-Corneal Rings (INTACs)

Introduction to INTACS

INTACS is an acronym that stands for intra-corneal rings. These are segments that are surgically fitted into the center of the corneal stroma. They even out the surface of the central cornea so that vision is improved.

INTACS are made and marketed by Addition Technologies. They are valuable for the healing of various eye conditions such as forme frusta, keratoconus with mild myopia, pellucid marginal degeneration and “forme frusta”. It can also strengthen a cornea that is to weak to take LASIK surgery for myopia.

History of INTACS

The Keravision company originally made INTACS. They were originally approved by the U.S. Federal Drug Administration for the therapy of mild myopia. Mild myopia is defined as eyesight that is deficient in the range of – 1 to – 3 Diopters. However with technological advancements such as the excimer laser and laser-assisted subepithelial keratomileusis (LASIK), INTACS became obsolete. This is because LASIK proved more accurate and easier to implement in the eye than INTACs. The result was that the Keravision Company went under.

Since, INTACS has been developed for the treatment of keratoconus specifically. Dr Joseph Colin in France spearheaded its development. In 2001, D. Colin researched a five-year study on a selected group of patients who were cured using these rings. Since the publication of his results, at least five other research groups have also done studies that prove the efficiency of INTACS.

In the United States INTACS may only be used under what is called a “human device exemption” which means they can only be implanted with the supervision of a review group.

Recently, United States sanctioned the use of INTACS for the treatment of keratoconus. However, it comes under a human device exemption, which permits its use only under the supervision of a review group. Currently INTACS diopters of 0.25, 0.275, 0.30, 0.325, and 0.35 mm are manufactured in the U.S.. The .40 and 0.45 mm-sized segments can only be purchased outside the United States.

It has also been reported in at least two published scientific reports that INTACS is effective when it comes to correcting astigmatism in patients who have pellucid marginal degeneration.

Latest developments in the implementation of INTACS have suggested its potential use for aiding individuals with non progressive type vision loss and thick corneas.

Applications of INTACS

INTACS can be of some assistance with the following conditions:

  • Mild to moderate keratoconus that has contact lens intolerance as long as the individual has clear corneas
  • INTACS is for lamellar keratoplasty for eyesight correction
  • As a refractive remedy for patients wearing either contact lenses or spectacles (this is not approved by the FDA in the United States
  • For treatment of extremely fragile corneas whose myopic error is less than three diopters. It is safer than laser refractive surgery

The surgical process

The surgical procedure consists of the following pre and post-operative steps:

  1. Selection of the appropriate size and dioptre of INTACS
  2. Incision
  3. Implantation of the devices through surgery
  4. Post-operative care

INTACS selection

There are various sizes of INTACS available. Hence, there are various possible permutations and combinations of INTACS as well, for implantation in the process of flattening of the core cornea and astigmatism correction. What is best is that whatever the combination used, there is always some desired result.

Incision

There are a variety of strategies that can be employed when it comes to inserting INTACS. A common practice is to place the incision on the steepest axis of the curve of the eyeball.

Surgery

Surgery was originally performed using a mechanical spreader but now a laser called the Intralaser is usually employed for this type of surgery. It is also known as the femtosecond laser.

The femtosecond laser allows the easy insertion of the intacts, is easy on both the surgeon and the patient, saves time and also allows for a second try if the first attempts at insertion are disappointment. The use of this laser also ensures a quicker post-operative recovery.

Post-operative care

The main issue when it comes to post-operative care is the use of contact lenses. Having a proficient contact lens provider is crucial.

Immediately after surgery it is advised that the patient wear soft disposable contact lens. Usually contact lens strength of around 3 D less then the prescription he or she had before the operation is suggested. This enables the individual comfort and the ability to see immediately after the operation. Some physicians will recommend customized contact lenses after an INTACS surgery.

Rigid contact lenses are best to use after three months after the cornea has settled, the stitches have been excised and the wound has completely heals.

Disadvantages of INTACS

INTACS do have drawbacks. The intraoperative and postoperative complications that can occur are:

  • Puncture of the anterior segment that damages the sclera and affects and superficial positioning of the INTACS
  • Infection from implanting the INTACS too near the edge of the incision
  • Erosion of an INTACS implant that has been improperly placed
  • Vision with halo and glare (especially common in young patients)
  • Rare symptoms like constant swelling, unstable eyesight, intraocular sensitivity, photophobia, can also occur as the result of INTAC implantation