Intrastromal corneal ring segment
An intrastromal corneal ring segments ( ICR or ICRS or Intacs ), also according to its manufacturer Keravision ring mentioned, is an implant for the cornea ( cornea ) of the eye . The ICRS have been in use since 1996. The ICR consists of two small ring segments that together have an inner diameter of 6.7 mm. These transparent plastic segments are made of PMMA ( polymethyl methacrylate ), the same material that has been implanted as a lens replacement in cataracts for around 30 years . They are pushed into ( intra ) the layers ( stroma ) of the cornea at the edge of the cornea, thereby flattening the central cornea. The tunnel incision required for this can be prepared with a blunt knife or with the femtosecond laser. Depending on the ring size, myopia can be between −1 dpt. and −4 dpt. Getting corrected. A corneal curvature should not be present.
The surgery should only be performed by an experienced corneal surgeon. The risk of a cutting error can be reduced when using the femtosecond laser . In the event of an over or under correction, the ring segments can be exchanged or removed again.
Although the results were very satisfactory and stable, this surgical procedure has not yet caught on because at the same time a procedure that is surgically easier to carry out, laser correction using an excimer laser , was created. One advantage of ICRS, however, is the reversibility of the procedure.
The ICRS are currently used primarily to stabilize the cornea in keratoconus .
See also
Web links
- Overview of different refractive procedures, u. a. ICRS (University of Salzburg)
- Keratoconus. Schematic animation of how the ICRS implantation in keratoconus works.
literature
- Thomas Kohnen: Refractive Surgery. Springer Medicine, Berlin et al. 2011, ISBN 978-3-642-05405-1 .
- Josef Ruckhofer: Clinical and histological studies on the intrastromal corneal ring segments. In: Clinical Monthly Ophthalmology. Vol. 219, No. 8, 2002, ISSN 0023-2165 , pp. 557-574, doi : 10.1055 / s-2002-34421 .
