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Ferrara Ring

The Ferrara Ring uses the latest technology, in constant evolution, to treat keratoconus. Our proprietary methodology, of international recognition, consists on a surgical procedure applied to the cornea, which corrects deformities caused by pathologies in the tissue and associated refractions.


The Ferrara Ring is made of Yellow PMMA, an acrylic that has been proved to be inert and biocompatible, used for decades to make intracorneal implants. The surgical instrument used to carry out implant operations was developed with ultimate technology. The ring has different thicknesses and diameters that guarantee the best result in each case.

  • Yellow PMMA
  • Apical Diameters: 5mm and 6mm
  • Flat Base
  • Variable Arch legth between 90 and 210
  • Variable Thickness from 0,15 to 0,30
  • Results based on experience.

The Ferrara Ring started its evolution in 1986 and soon surgeons of Brazil and abroad showed interest in it. Since its introduction to the market more than 100.000 implants have been carried out with an extremely high success rate. See our publications section for scientific evidence.


The main indication for the Ferrara Ring implant is the keratoconus. In patients wit this disease it is indicated when there is evidence of progressive worsening, with gradual decrease of uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) and progressive corneal steepening. In patients with unsatisfactory BCVA with glasses and intolerance to contact lenses the Ferrara ring implantation is also indicated.
In post-LASIK corneal ectasia the Ferrara Ring implant is indicated when there is worsening of the condition.


The main contraindication for Ferrara Ring implants is the presence of apical opacities in very advanced keratoconus, usually with K readings above 75 D. The postoperative results in these cases are usually poor and the best treatment for them is the lamellar or penetrating keratoplasty.

Mechanism of action

The corneal ring complies with Barraquer and Blavatskaya postulates. According to these, an addition in the cornea periphery results in its flattening, and the ring diameter determines how much the cornea will be flattened. Thus, the more tissue is added (increasing ring thickness) and the smaller the diameter, the greater will be the myopia correction obtained.

Our study resulted in the additional observations presented below:

• Central and peripheral flattening of the cornea, preserving its asphericity.

• Decrease in the anterior chamber depth as shown in ultrasonic biomicroscopy.

• Regularization of the corneal surface through a tilting movement caused by the flatness in the surface of the ring basis, making the cornea flattened at the areas corresponding to the segments extremities and making it curve at the ring's body area.

Interruption, or at least delay of keratoconus evolution, diminishing opacity on the cone apex, and reduction of related symptoms as itching, photophobia and pain and/or ocular discomfort.

• Lack of correspondence between visual acuity uncorrected after surgery and residual ametropia. Sometimes it can be observed good vision coexisting with high residual refractive errors.

• The prisma effect generated by the triangular section eliminates the halos and glare, which could result from the small diameter of the orthesis.

• The yellow filter introduced in the plastic avoids the UV light to go into the eye reducing thus the halos and reflections at night.


The nomogram has evolved as the knowledge about the predictability of results has grown. Initially, surgeons implanted a pair of symmetrical segments in every case. The incision was always placed on the steep meridian to take advantage of the coupling effect achieved by the rings.

First, only the grade of keratoconus was considered for the ring selection, which means that in keratoconus grade I the more suitable Ferrara ring for implantation was that of 150 µm and in the keratoconus grade IV the more appropriate ring was of 350 µm. However, some cases of extrusion could be observed as in keratoconus grade IV the cornea usually is very thin and the thick ring segment sometimes was not properly fitted into the corneal stroma.

The second generation of the nomogram considered the refraction for the ring selection, besides the distribution of the ectatic area on the cornea. Therefore, as the spherical equivalent increased, the selected ring thickness also increased. However, in many keratoconus cases the myopia and astigmatism could not be caused by the ectasia itself but by an increase in the axial length of the eye (axial myopia). In these cases, a hypercorrection by implanting a thick ring segment in a keratoconus in which a thinner segment was indicated was observed.

In the third and actual generation of the Ferrara Ring Nomogram, the ring selection depends on the type of keratoconus, its location in the cornea, corneal asphericity (Q), topographic astigmatism and pachymetry.
For symmetric bow-tie patterns of keratoconus, two equal segments are selected. For Nipple cones, a single 210 µm segment is chosen based on the nomogram. For peripheral cones, the most common form type, asymmetrical segments are selected.


The Ferrara ring has received approval to be used in Europe, obtaining all the certificates demanded by the Medical Directive of the European Union. It is also approved for use in Brazil, Mexico, Cuba, Saudi Arabia, Argentina and Uruguay.


Ferrara Ring is manufactured under all the quality standards and the highest quality tests according to ISO 9001, ISO 135485 and CE mark. This is how we guarantee the efficacy of our product and the authenticity of the ring.


• Low morbidity, because it preserves the cornea structure and has a low rate of complications, allowing 95% of the operated patients to quickly reintegrate themselves to their everyday activities.

• Reversibility, because it enables the cornea to revert to the preoperative dimensions when the segments are removed.

• Readjustability through segment replacement. In some cases, it was possible to correct hypercorrection removing just one of the segments.

• Lack of rejection. The acrylic, which the ring is made of, is inert and biocompatible.

• Patients´ high satisfaction rate.

• As an orthopedic technique, it corrects corneal deformity and restores the physiologic curvature. After the surgery, it is possible to correct the residual ametropia with conventional optical correction or contact lenses.

• Stabilization or delay of cone progression.

Lack of a minimum age for surgery, thus making it possible to reduce the wait lists for transplants in eye banks (30% of the transplants in eye banks are attributed to keratoconus).

• Possibility of association with other procedures like contact lens fitting and intraocular lenses.

• No interference whatsoever with corneal transplant


• Ferrara Spatula
• Suarez Spreader
• Bicalho Guide
• Pre-delaminator
• Ferrara marker
• Sinskey hook of 0,20mm
• Modified McPherson Forceps
• Adjustable Ferrara Diamond Blade Knife

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