ANNULAR INTRA-CORNEAL INLAY FEATURES
Abstract: As proposed in 1978, the intra-stromal corneal rings began to use for myopia adjustment. The purpose of this method is to lessen the sphero-cylindrical refractive error by reducing corneal curvature and diminishing the higher-order aberrations due to increasing in corneal regularity. Today, the intra-corneal rings commonly uses for corneas with mild to moderate keratoconus, provided that the cornea has no central scar and the patient could not tolerate contact lenses. Inserting the rings inside the cornea increase the centrality of the corneal apex, thereby facilitating contact lens fitting and enhancing comfort as well as increasing in best corrected visual acuity. Changes in corneal situation is described by the Barraquer’s law, in which when a material is increased in the corneal periphery or decreased in the center of the cornea, a flattening effect is enhanced. Intra-corneal rings generally fall into two categories: 1.Intra-Corneal Ring Segments (ICRS) up to 355 degree arc such as Ferrara ring (Ferrara Ophthalmic Ltd.), Intacs (Addition Technology Inc.), and Keraring (Mediphacos Ltd.) 2. Intra-Corneal Continues Complete Rings including Myoring (Dioptex GmbH, Austria) and Annular Intra-Corneal Inlay (AICI, Ophthalight cor. Tehran, Iran). The AICI is available in 4 different thicknesses (140, 160, 180 and 200 microns) that will be selected depending on the corneal conditions. One of the features of AICI is that unlike Myoring, it is not flat and these rings are made in a curved shape with a base curve of 7.4. Therefore, due to the similarity close to the curvature of the cornea, it is expected that the changes created will be different from other rings. This study evaluates the structural features, patient selection and specific results following the AICI implant inside the keratoconic cornea.