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Coral Used for Eye Implants

By Dalia Acosta*

Not gold, not ceramics or glass are as efficient as sea coral for replacing damaged human eyes, Cuban scientists tell Tierramérica. The procedure is already being applied and is known by its initials HAP-200.

HAVANA - Material originating in the sea coral from the reefs around Cuba, long used for human bone reconstruction, have proven effective in the creation of eye implants, and is extracted from the environment without harming the fragile coral ecosystem.

Officially registered as hydroxyapatite porous coral HAP-200, the product is being used in meeting one of the scientific challenges that has persisted since the 14th and 15th centuries when scientists began looking for ways to remedy traumas to the human eyeball.

Spheres of precious metal, including gold, ceramics or glass have been used as implants to replace damaged eyes, but none has demonstrated the potential of coral for preventing biological rejection and ensuring a natural-looking eye.

Any of the patients treated in Cuba in recent years can prove it. David Díaz, looks directly at the person he is conversing with, and glances aside, without any noticeable difference between his healthy eye and the artificial one.

"Life is porous, and so is coral," quipped chemist Ramón González, who is part of the interdisciplinary team that created HAP-200.

The advantages of coral have to do with its porous properties, which allow it to interrelate with the medium surrounding it, and its chemical composition is very similar to the bone tissue of humans, he explained in a conversation with Tierramérica.

"Sea coral is a polyp with an external calcareous skeleton. That structure is produced by a living organism and made to sustain a life that lives in a very permeable way," González said.

It is from that external skeleton that experts from the biomaterials laboratory of the National Scientific Research Center (CNIC), directed by González, obtain the hydroxyapatite porous coral.

The sphere implant is placed in the socket of the lost eye, and its porous quality allows the surrounding tissue to penetrate it, creating an extensive network of blood vessels and providing mobility for the artificial eye. The success of the external prosthesis depends on the internal effectiveness of the implant.

The prosthesis is created, based on the needs of the individual patient, at the Cuban Center for Facial Restoration and Maxilofacial Prostheses.

"It is personalized treatment. Everyone does not have the same sized eyes, or the same color or shape. And we all speak with our eyes," commented González.

Follow-up on 43 patients in Cuba has shown that in 95 percent of the cases, the organism tolerated the implant. There is "high biocompatibility, an absence of adverse reactions and there are excellent esthetic results," says one study.

Outside of this socialist-run island, similar coral-based products are manufactured only in the United States and France.

Since the patent registration of Cuban coral in 1992, the implants have benefited 3,500 patients needing maxilofacial surgery, 2,000 with orthopedic and trauma needs, and 800 with eye injuries.

The chief of the CNIC Biomaterials Lab believes Cuba has a "privileged opportunity" with its coral bank, particularly due to its high purity. The coral reefs cover more than 98 percent of the nearly 4,000-km border of the Cuban marine platform.

The World Atlas of Coral Reefs, published by the United Nations Environment Program (UNEP), rates Cuba 21st of the 80 countries with greatest coral reserves.

However, more than 60 percent of the Caribbean coral reefs are threatened by sedimentation, contamination and over-fishing, says the UN report.

González states that in the production of HAP-200, coral of the rapidly regenerating porite family are used, and that only those that have been broken as a result of wave action and winds are extracted.

Gathering of the coral material for producing the eye implants may only be carried out by specialized staff of the Cuban Oceanography Institute, and they must follow standards set to protect sustainable use of marine resources.

* Dalia Acosta is an IPS correspondent.


Copyright © 2001 Tierramérica. Todos los Derechos Reservados
 

Photo: Cuba possesses extraordinary wealth in coral. /Credit: Claudio Contreras.
 
Photo: Cuba possesses extraordinary wealth in coral. /Credit: Claudio Contreras.