Notwithstanding all the advances in the items below, no substantial change was made to the corneal rings for the last ten years. And this is the scenario for the Cornealring birth. By building on the significant knowledge gathered from these implants, a new proposal was launched for the ring design, aiming at improving, fitting and correcting some failures that had become evident in the old models over time. Therefore, this does not refer to the launching of a new product, but to the evolution of these tools which are becoming the option of choice for the management of keratoconus.

• The Origin
• From 1949 to 1978
• In 1978
• In 1986
• In 1989
• Up to now

• The Origin

  The first oldest refractory surgical procedures included removal or addition of corneal tissue. With the help of a microkeratome and freezing procedures, a thin stromal lamella was removed from the cornea in order to flatten it (keratomileusis) and correct the patient's myopia. Alternatively, in order to increase the corneal curvature of the hypermetrope eyes, a stromal lamella from a donor eye was implanted at the receptor cornea (keratophakia). However, this procedure did not last long, due to the equipment complexity, the difficult surgical procedures and, the most disappointing fact of totally variable outcomes. Soon it was noted a run towards the development of less traumatic procedures, implying smaller scars and that could be more predictable. Back to top

• From 1949 to 1978

  The use of intracorneal synthetic implants to correct refractive errors was first visualized by Barraquer in 1949, who introduced the term Refractive Keratoplasty, that is, a corneal plastic surgery to correct refraction (Barraquer JI. Refractive Keratoplasty. Este Inf Oftal 1949;2:10-30). However, the first results achieved were not encouraging due to biocompatibility problems, lack of permeability to nutrients and oxygen, changes to the lenses hydration conditions etc. As these lenses implied surgical manipulation of the optical zone of the cornea, a risk existed to scar formation and reduction of the eye optical portion transparency. In the following years, extensive research was carried out to try and find a biocompatible and permeable material, with good optical quality and high refraction rate (Barraquer JI. Modification of refraction by means of intracorneal inclusions. Int Ophthalmol Clin 1966;6:53-78. McCarey BE, Andrews DM. Refractive keratoplasty with intrastromal hydrogel lenticular implants. Invest Ophthalmol Vis Sci 1981;21:107-15. Choyce DP. The correction of refractive errors with polysulfone corneal inlays. A new frontier to be explored? Trans Ophthalmol Soc U K 1985;104:332-42). To avoid manipulation of the visual axle region, and prevent loss of transparency, several attempts were made to change the cornea curvature by manipulating only its peripheral portion. Blavatskaia, D. E. D., carried out trials with rings made of human cornea, which were inserted into the receptor stroma to correct its myopia. He has also developed a table (nomogram) for the definition of the correct ring thickness to be applied. This nomogram correlated the ring thickness to the amount of myopia to be corrected (Blavatskaia, D. E. D., "the use of intralamellar homoplasty in order to reduce refraction of the eye" Uberstzt. Aus. Oftalmol. Zh. (1966) 7:530-537 which was apparently translated to Arch. Soc. Ophthmol. Optom. (1988) 6:31-325). Back to top

• In 1978

  Alvin E. Reynolds has developed an "Intrastromal Corneal Ring" (ICR) (USA patent number 579480 in 1987; number 4766895 in1988). In Brazil, the first clinical trials with human beings took place in 1991, with a full 360° arch length ring (ICR) inserted into blinded eyes. This implant underwent changes, particularly when it was split into two 150° arch length segments each ("Intrastromal Corneal Ring Segments - ICRS"). In 1999, the ICRS term was changed to INTACS. New changes to its morphology started to be studied in 2006, with the launching of an elliptical cross-section model. Back to top

• In 1986

  In Brazil, Paulo Ferrara de Almeida Cunha, MD, started studying diameter-reduced PMMA rings in animals, with a view to use them for high myopia correction purposes. Following implants into blinded eyes, in 1991, he performed the first ring implantation with refractive correction purposes. At that time, it was a full 360° arch length ring inserted under a flap made with a microkeratome (such as in LASIK). In 1995, the first ring was implanted in a subject following cornea transplantation and radial keratotomy. As of 1996, the use of these rings was offered to keratoconic patients intolerant to contact lenses and with indication to cornea transplantation. Back to top

• In 1989

  In 1989, Fleming issued his work with a malleable ring that, after having been inserted into the cornea, may be compressed or dilated to allow a more curved or flattened given meridian. (Fleming JF, Wan WL, Schanzlin DJ. The theory of corneal curvature change with the Intrastromal Corneal Ring. CLAO J. 1989 Apr-Jun;15(2):146-50). Back to top

• Up to now

  Steven B. Siepser (USA patent number 4976719 in 1990) shows another type of ring able to reduce or increase the cornea curvature with a single surgical wire that builds a circle to which forces are selectively adjusted. To make this change on a controlled way, he has also developed a tensor that was attached to the wire. Gabriel Simon (USA patent number 5090955 in 1992, and number 5372580 in 2001) describes a surgical procedure that allows changing the cornea curvature by an intralamellar injection of a synthetic gel at the cornea periphery, thus sparing the optical zone (Simon, Gabriel et al., "Gel Injection Adjustable Keratoplasty," Graefe's Arch Clin Exp Opthalmol (1991) 229:418-424, pp. 418-424). Thomas Silvestrini et al. (USA patent number 5466260 in 1995) describes an intrastromal adjustable corneal ring (ICR), but highlights that the invention essence is the discovery that the ring should be adjusted in its thickness, so there is no need to produce different-sized rings. The ring should be chosen prior to surgery and he advocates that "the device should not be readjusted after insertion". Joseph Y. Lee (USA patent number 5876439 in 1999) describes an injectable ring made of a silicone-similar material, or urethane polymer. After injection, if necessary, the cornea curvature is selectively adjusted and part of the injected fluid is removed to reduce the implant volume on a discrete and controlled way. As it can be seen, the idea to introduce an intralamellar device in the stroma is not new and several materials were and continue to be tested. Thousands of rings in several shapes had already been implanted around the world. The most popular ones, thanks to their better performance and reproducibility were those manufactured with rigid acrylic material (PMMA) with a triangular or hexagonal cross-section and available in several sizes and thicknesses. This type of surgery is being rapidly spread worldwide thanks to the physicians and patients' satisfaction with results achieved. This good performance is in part a result of the advances in its indication, implantation procedure, instrumentarium etc., to read: Indication: Initially, this surgery was regarded as REFRACTIVE, but now it is recommended specially to treat diseased corneas, such as the keratoconic ones. The first objective was to reduce myopia; now it is aimed mainly at providing a better corrected visual acuity and hold/slow the ectasia progression. Surgical procedure: Initially, the rings were implanted into bags or under flaps; now they can be inserted under less traumatic procedures. The surgery may be carried out in two ways: the Manual Procedure, by making a tunnel with a proper curved spatula, or the Phentosecond-laser Procedure in which the tunnels are created by laser. Surgical instrumentarium: all parts of the surgical instrumentarium sets were practically changed and others were added to allow the surgeon to perform on an easier, safer, more accurate and reproducible way. Back to top