Intacs™,
made by KeraVision, is a non-laser
procedure with FDA approval for use in patients with low amounts of myopia
(-1.00 to -3.00 diopters of myopia with up to +1.00 diopters of astigmatism).
The commercially available segments in the U.S. are intended to correct low
amounts of nearsightedness but not astigmatism. The procedure
involves the placement of two plastic segments within the non-seeing periphery
of the cornea.
These segments flatten the central cornea without removing tissue to
better focus light.
The segments are made of the same material that’s been implanted in
human eyes after cataract surgery for nearly 50 years, called PMMA (polymethylmethacrylate).
Intacs have the advantage of removability or exchangeability for
different sized segments, and maintaining a more natural corneal shape.
The more natural corneal shape may provide better vision than LASIK.
Intacs received FDA approval in April 1999. From April to December 1999, 2,000 Intacs procedures were performed in the U.S. In comparison, currently almost 4,000 LASIK procedures are performed daily in the U.S. The data from the FDA clinical trials were impressive for Intacs, indicating significantly more Intacs patients achieving better than 20/20 vision. However, surgeon skill is even more important in Intacs than LASIK for a successful outcome.
To my knowledge this device is no longer being used. As with many surgeries, newer and better procedures and devices are constantly replacing less successful ones.
KeraVision is also sponsoring studies for correcting higher levels of myopia, hyperopia, astigmatism, and an infrared laser made by IntraLase to make the corneal channels needed for segment implantation. One emerging use of Intacs is for an eye disease called keratoconus, a condition that affects an estimated 1 in 2,000. In keratoconus, the corneal surface is irregular and causes poor vision. Clinical studies are underway for better characterizing Intacs for keratoconus.