Intacs® are curved, tiny segments that are placed in between the layers of the cornea during a 10 minute, painless procedure.
Patients typically describe the procedure as “easier than getting my teeth cleaned at the dentist.” You won’t feel the Intacs® after it’s tucked under the cornea, just as you do not feel a dental filling for a cavity.
The segment’s specific design makes them an integral and common treatment for keratoconus and keratoectasia.
The goal of Intacs® is to improve vision by reducing the distorted corneal shape caused by the bulging cone. Depending on the level of keratoconus prior to Intacs® placement, patients can expect improvement ranging from:
- enhanced uncorrected vision without any lenses,
- better vision in contacts and glasses,
- moving out of one type of contact lens into another (example, being able to switch from rigid gas permeable (RGP) lenses to soft contact lenses), or
- improved fitting and vision with current RGP or SynergEyes® lenses being worn.
Joseph Colin, MD in France first reported the use of Intacs® for keratoconus. In 1999, Brian S. Boxer Wachler, MD of Beverly Hills, California was the first in the United States to use Intacs® for keratoconus and added many refinements to the technique including customizing the entry point for each eye and inventing use of single segments. Dr. Boxer Wachler published one of the largest studies to date which was in part used by the FDA for the approval of Intacs® for keratoconus. The first technique used two asymmetrical segments – a thicker Intacs® segment below the cone and a thinner Intacs® segment above the cone.
With Dr. Boxer Wachler’s discovery that using a single Intacs segment yielded a unique result: flattening of the cone adjacent to the segment and steepening of the cornea 180 degrees away in the area that was relatively too flat. This is the ideal improvement in corneal shape from keratoconus – flatted lower cornea (which is too steep) and steeped upper cornea (which is too flat). It is called the “bean bag” effect, like when you sit in a bean bag that bag under your seat gets flat while the upper part of the bag pops up. In a follow-up study, it was found that for peripheral cones, which are the vast majority of patterns of keratoconus and keratoectasia (keratoconus after LASIK), single segments had superior results compared to double segment implantations. Use of two segments causes global flattening which includes unnecessarily flattening the already flat upper part of the cornea.
Combining Corneal Collagen Crosslinking with Riboflavin with Intacs®
Intacs® enable targeted flattening of the cornea. However they do not treat the underlying structural problem, which is weakened collagen. Therefore Corneal Collagen Crosslinking with Riboflavin, also known as Holcomb C3-R® or CXL, was combined with Intacs® in patients with keratoconus for maximal effect on the cornea. A research team evaluated the results of Intacs® alone vs. Intacs® immediately followed by Corneal Collagen Crosslinking with Riboflavin. The study found that there was additional improvement in corneal shape with the combined treatment compared to Intacs® alone. This study was recently published.
Corneal Collagen Crosslinking with Riboflavin has been used to treat patients with keratoectasia as well. The long term results are very good. The procedure has been proven to be very safe. Corneal transplantation seems preventable in almost all of these patients.
After initial reports, many studies have subsequently been conducted to evaluate Intacs® for keratoconus. Intacs® provide a unique ability to modify the shape of the keratoconus. This in turn can lead to improvement in vision and reduction of astigmatism and myopia. The goal of each patient depends on the degree of keratoconus being treated. The goal of Intacs® is to improve patients’ ability to function in corrective lenses such as soft lenses, hybrid lenses, RGP lenses, or glasses. In more mild cases of keratoconus, the goal is to improve vision without the need for wearing any form of corrective lenses.