ASCRS San Francisco 2009 Corneal Ring for High Myopia: New Technique. Albert Daxer, Austria. The author is investor in DIOPTEX GmbH.

ASCRS San Francisco 2009 Background Refractive laser surgery for high myopia may be vision-threatening for biomechanical reasons. A current alternative to laser surgery in high myopes is intra-ocular surgery, including clear lens extraction and implantation of phacic IOLs or ICLs. Implantation of intra-corneal ring segments is minimally invassive, however, it is either limited to low myopia (Intacs) or it is not applicable to high myopia for centration problems (Ferrara Ring, KeraRing).

ASCRS San Francisco 2009 Corneal Intrastromal Implantation Surgery (CISIS) The author has developed a new kind of intra-corneal surgery including a new kind of microkeratome and a new kind of intra-corneal implant for the treatment of moderate and high myopia. The objectives were: –The treatment should be minimally invassive (no intraocular surgery, no removal of tissue, no weakening of the biomechanical stability of the cornea). –The treatment should be reversible. –The treatment should be quick and easy to perform in an outpatient procedure. –The entire dioptic range of shortsightedness should be accessible.

ASCRS San Francisco 2009 Corneal intrastromal implantation surgery (CISIS) 1st step: Creation of a closed intra-corneal pocket using a new kind of microkeratome (PocketMaker). The PocketMaker microkeratome has CE-mark but is not approved by FDA. 2nd step: Insertion of a new kind of intra- corneal implant (MyoRing) into the corneal pocket via a small incission tunnel. The MyoRing is a flexible full-ring implant which can be positioned easily within the corneal pocket after insertion. The MyoRing has CE- mark but is not approved by the FDA.

ASCRS San Francisco 2009 Result The MyoRing implant in situ appears like a hard contact lens, however, less visible.

ASCRS San Francisco 2009 Refractive results after 6 months (latest nomogram)

ASCRS San Francisco 2009 Reversibility The new kind of treatment is reversible. The spherical as well as the cylindrical component of the refractive error after removal of the implant returned almost always exactly to the preop value.

ASCRS San Francisco 2009 Possible complications and side effects Decentration. Induced astigmatism. Residual refractive error. Regression. Glare, halos and night vision problems.

ASCRS San Francisco 2009 Biomechanical considerations Cutting only parallel to the static elements (collagen lamellae) of the biomechanical framework of the cornea, which run parallel to the intra-corneal tension, does not result in biomechanical weakening of the tissue. If, however, the cut runs perpendicular to the collagen fibrils (perpendicular to the tension lines), the cut can weaken the cornea.

ASCRS San Francisco 2009 Biomechanics: LASIK vs. CISIS LASIK creates a flap by cutting perpendicular to the tension within the cornea along almost the entire circumference and, therefore, reduces both, effective corneal thickness and corneal stability. CISIS can be considered as an inverse LASIK procedure which do not cut perpendicular to the collagen fibrils (except the small tunnel) and does, therefore, not harm the stability of the cornea. It creates an almost entirely closed corneal pocket.

ASCRS San Francisco 2009 Conclusion Corneal intrastromal implantation surgery (CISIS) is save and effective for the treatment of moderate and high myopia. CISIS is quick and easy to perform as an outpatient procedure under topical anesthesia. The procedure is reversible. Possible complications and side effects include residual refractive error, decentration, induced astigmatism, regression, glare, halos and night vision problems. Most possible complications and side effects are manageable by simple interventions.