Integrating the latest

advances in intrastromal
segment technique

Integrating the latest

advances in intrastromal
segment technique

Cornealring: Intrastromal segments

Cornealring is a medical device used to treat keratoconus and other corneal diseases. It comprises several semi-circular segments of an inert material, the polymethyl methacrylate (PMMA), with length and thickness designed to fit the specific features of the eye. The device is clear so it is not easily seen at naked eye.

Cornealring is implanted at the cornea stroma, through a simple surgical procedure lasting a few minutes and carried out under topical anesthesia (only eye drops). The cornea structure is kept unchanged, sparing its optical zone (central), which is its most noble region.

The goals of this type of surgery are:

  • To correct the cornea and improve the eye visual corrected acuity, thus easing contact lenses fitting.
  • To hold or slow progression of corneal diseases causing the cornea to become more and more curved and irregular.

The patient shows a very high satisfaction level following the Cornealring implantation. However, if results are not satisfactory, this type of procedure has the great advantage of being reversible and readjustable. Also, the procedure does not preclude future transplantation, if needed.

Nomograma Cornealring Visiontech

Cornealring Simulator

See examples of hypothetical applications of different segment arc lengths in different corneal topographies.


Simulate now

Advantages of the Cornealring

Cornealring incorporates advances in its design, aiming at better clinical performance:

Fusiform cross-section
Fusiform cross-section

The design resulted from the observation of "empty spaces" subjacent to stromal implants. This allows a perfect adaptation and housing of the segment in the cornea.

Greater biocompatibility

Corneal segment of latest generation; rounded cross-section in “spindle” (fusiform) shape improves anatomical compatibility, allowing better accommodation and preserving corneal integrity.


The anterior curvature is more accentuated than the posterior one

As these segments are at an 80% deep implanted, there are a higher number of lamellae to absorb compression in their anterior face.

Large tapering of inner and outer edges

It helps segment involvement by the corneal lamellae.

Bent base
Bent base

It follows the corneal lamellae, which are also bent at the site of the segments implantation (as the cornea is curved, not straight).

Curvilinear profile

The ring curved surface distributes the compression forces throughout a larger corneal surface, thus avoiding the creation of significant metabolic suffering and, therefore, less risk of superjacent deepithelization.

Healthier superjacent epithelium

Resulting from the ring major biocompatibility, it thus eases the postoperative contact lenses fitting. A healthy epithelium also provides a more regular and better optical quality corneal surface.

Advantages of the Cornealring
Advantages of the Cornealring
Minor glare

The ring has a 4.7 mm inner diameter, higher than the 4.4 mm of the traditional triangular segments (14% increase).

A. Pupil in miosis

Traditional triangular ring represented in yellow, Cornealring in blue. The patient normally views the image in a bright environment.

B. Pupil in mydriasis

Small diameter rings cause glare early in low light environments. The patient complains of cloudy vision in his peripheral visual field.

Scientific Publications

Surprising astigmatism hypercorrection after corneal ring segments implantation in keratoconus treatment after 8 years of follow up

Guilherme Malta Pio; Frederico Malta Pio; Alessandra Mariano Caldeira Coelho; Carolina Serpa Braga; Anna Flávia Ribeiro Pereira; Caroline Alves Cotrim; Frederico Bicalho Dias Silva. Romanian Journal of Ophthalmology, Volume 65, Issue 1, January-March 2021. pp:80-84.
https://rjo.ro/wp-content/uploads/2021/03/15.Guilherme-Malta-Pio_RJO_2021.pdf

Efficacy of Different Procedures of Intra-Corneal Ring Segment Implantation in Keratoconus: a Systematic Review and Meta-Analysis

Cédric Benoist d’Azy; Bruno Pereira; Frédéric Chiambaretta; Frédéric Dutheil. Translational Vision, Science and Technology, 2019.
https://tvst.arvojournals.org/article.aspx?articleid=2735970

Efficacy of different procedures of intracorneal ring segment implantation in keratoconus: a systematic review and meta-analysis of the last ten years

Cedric Benoist D’Azy. Doctoral thesis. Université de Clermont-Ferrand I, 2017. 

Evaluación del tratamiento de las ectasias corneales mediante el implante manual de segmentos de anillo intracorneales en un hospital de nivel 1

Nicolás R. López Ferrando. Doctoral thesis. Universidad Francisco de Vitoria, 2017.
https://dialnet.unirioja.es/servlet/tesis?codigo=118322

Femtosecond-assisted intrastromal corneal ring implantation for keratoconus treatment: a comparison with crosslinking combination

Peter Alexander von Harbach Ferenczy; Maiara Dalcegio; Marcela Koehler; Thiago Silveira Pereira; Hamilton Moreira; Luciane Bugmann Moreira. Arquivos Brasileiros de Oftalmologia v78 nr 2 2015 pg. 76-81.
https://www.scielo.br/scielo.php?script=sci_arttext&pid=S0004-27492015000200004&lng=en&nrm=iso&tlng=en

Intrastromal corneal ring segment implantation for ectasia after refractive surgery

Larissa Rossana Souza Stival; Belquiz R. do Amaral Nassaralla; Marisa Novaes Falleiro Chaves de Figueiredo; Frederico Bicalho; João Jorge Nassaralla Junior. Arquivos Brasileiros de Oftalmologia v78 nr 4 2015 pg. 212-215.
https://www.scielo.br/scielo.php?pid=S0004-27492015000400212&script=sci_abstract

Anillos intracorneales de 5mm versus 6mm en el tratamiento de la ectasia corneal: estudio comparativo

Mar Agudo Iturriaga. Doctoral Thesis. Universitat de Valencia, 2014.
https://core.ac.uk/download/pdf/71031175.pdf

Segmento de anel corneano de comprimento de arco grande / Segmento de anillo corneano de longitud de arco grande

Frederico Bicalho Dias da Silva; Vinícius Coral Ghanem. Revista Oftalmologia em foco nr. 163 pg. 32-34.
https://oftalmologiaemfoco.com.br/associado-digital/

Keratoconus therapeutics advances

Martha Jaimes; Arturo Ramirez-Miranda; Enrique O Graue-Hernández; Alejandro Navas. World Journal of Ophthalmology 2013 vol 3 nr. 3 pg 20-31.
https://www.wjgnet.com/2218-6239/full/v3/i3/20.htm 

Avaliação da eficácia do segmento de anel corneano de 300 graus de arco na correção do astigmatismo ceratométrico em olhos com ceratocone

Frederico Bicalho Dias da Silva, 2013.
https://www.webartigos.com/artigos/avaliacao-da-eficacia-do-segmento-de-anel-corneano-de-300-graus-de-arco-na-correcao/144250

Tratamento do queratocone com implante de aneis intra-estromais por laser femtosegundo – Resultados de acordo com a nova classificação SAANA

Andreia M. Rosa; João Cardoso; Helena Vasconcelos; Miguel Ribeiro; Inês MArques; Jorge Henriques; Maria João Quadrado; Joaquim Murta. Revista Oftalmologia Vol 35 pg 253-258.
https://silo.tips/download/tratamento-do-queratocone-com-implante-de-aneis-intra-estromais-por-laser-femtos

Intrastromal Corneal Ring Segment Implantation for High Astigmatism on Postkeratoplasty Eyes

B. A. Nassaralla; J. J. Nassaralla, Jr. Investigative Ophthalmology & Visual Science – ARVO/IOVS Journals. April 2010, Vol.51, 4222.
https://iovs.arvojournals.org/article.aspx?articleid=2372848

Anillos corneales intraestromales

Javier Celis Sánchez; Diana Mesa Varona; Eva Maria Avendaño Cantos; Sonia López-Romero Moraleda. Revista Superfície Ocular nr. 41 pg.
https://docplayer.es/13529215-Anillos-corneales-intraestromales.html