Implantable textile

Aayushee Ghorpade

Veermata Jijabai Technological Institute,Mumbai


Retracting decades of human existence, life and death is where everything revolves around. Right from birth to cremation, the human body undergoes numerous changes in terms of  growth of essential and non essential parts(leading to dysfunctioning), blockages and failures as well. Medical textiles necessitate solutions to all the stumbling blocks by either treating the existing body parts or replacing them with the artificials, requiring immense attention as it is directly connected to the human beings.

Classification of Medical Textiles :

  • Non-implantable materials: Wound dressings,bandages,plasters,etc.
  • Implantable materials: Sutures, artificial tendon (mesh), artificial ligaments, artificial    vascular grafts,etc
  • Extracorporeal devices: Artificial leg ,artificial kidney,artificial liver,artificial lung,etc
  • Health and hygienic Care: Surgical gowns,gloves,masks,wipes,etc

Implantable Medical Textiles :

Unlike transplants of biomedical tissues, an implant is a man-made medical device that is manufactured to replace or support the dysfunctioning or missing biological structure, or enhance the working of the existing one. The surface of the implant is coated with organic or inorganic materials such as titanium, silicone or apatite depending on function, thereby providing high biocompatibility with the human body, normal metabolism and resistance against harsh environments during their use.In certain cases implants contain electronics artificial pacemaker and cochlear implants and bioactives such as subcutaneous drug delivery devices in the form of implantable pills or drug-eluting stents.

Artificial Lens :

Due to ageing or unacceptable circumstances ,the natural lens in the eye which focuses light and images on the retina to be perceived by the brain loses its ability to do so, resulting in the formation of a cloudy appearance on the natural lens (colloquially called a cataract)

To treat cataract or the for correction of refractive errors, such as nearsightedness (myopia), farsightedness (hyperopia), astigmatism, and presbyopia, surgical replacement with an optical device such as artificial lens, known as an ophthalmic lens, intraocular lens(IOL) or psuedophakos takes place.

Fibres and properties :

Artificial lenses are made up of inert or non-reactive materials, such as Poly(methyl methacrylate) or PMMA, also known as acrylic glass, silicone, and acrylic.

PMMA is a transparent thermoplastic often used as a lightweight sheet having high tensile strength, flexural strength, transparency, polishability, UV tolerance,chemical resistance and heat resistance,high scratch and impact resistance.The hard PMMA IOLs are usually cut by a precision lathing machine.

As a substitute, hydrophobic acrylic polymers are used which generally do not absorb liquids(with a water percentage less than 1% of their overall weight).

Classification of Artificial Lenses :

Ophthalmic lenses are divided into two classes based on whether the natural crystalline lens is absent (aphakic) or present (phakic).

  • Aphakic lens : Aphakic lenses are artificial intraocular lenses that replace a surgically removed natural crystalline lens that are implanted after cataract surgery.
  • Phakic lens : Phakic lenses are artificial lenses that work together with the natural crystalline lens to correct refractive errors.These are cornea lenses positioned in the anterior and posterior chamber of the eye.

Types of Artificial Lenses :

  • Monofocal Lens : Monofocal lenses are most commonly implanted and provide only one type of  clear vision either at distance or near. But It is possible to implant a monofocal lens in one eye for distance vision and a monofocal lens in the other eye for reading vision. This technique is called monovision and can provide clear vision at both distance and near after cataract surgery.
  • Multifocal Lens : Multifocal lenses provide more than one type of clear, vision both at distance and near simultaneously.
  • Hi-tech variable-focus Lens : Variable-focus Lenses are used to correct presbyopia which involves to retrieve the auto-focus function of the natural crystalline lenses.

Manufacturing Process :

  • Ophthalmic Lens is manufactured from a hydrophobic elastomeric acrylic polymer resulting in the formation of a pre-polymer gel which forms the direct molding of all or  the optical portion of the lens using a fused silica mold.
  • The extracted lenses remain transparent and substantially glistening-free in an aqueous medium at 37 C.
  • Ocular implants are fabricated into a desirable shape and dimension either by machining such as using a computer based lathing machine or direct by molding.

Direct Molding :

  • A cavity with desirable dimensions and surface finish is created in the mould in which appropriate material is transferred and then shaped permanently.
  • In an intraocular lens (IOL), a perfectly curved and highly smooth surface finish  is required, so that the lens can provide sufficient optical power and resolution.
  • Major requirement for the direct molding of an IOL made from hydrophobic elastomeric acrylic polymers is that the polymer composition needs to have a desirable viscosity which is usually done by the preparation of a pre-polymer gel.The process is basically a partial polymerization of the mixture solution of the all the necessary components such as monomers, UV absorbant substances, crosslinkers and initiators which can be stopped when the viscosity increases to a desirable level.
  • The prepolymer is then filtered to remove all small impurities and is ready for casting IOLs in the mold.
  • Another requirement is that IOLs need to be easily removable from the mold without sticking.
  • In an IOL,a three dimensional cross linked network is attained by an optimized curing process.
  • Followed by, is the extraction process wherein, highly pure IOLs without leachable impurities are manufactured in order to eliminate glistenings.
  • Direct molding is most suitable for the fabrication of foldable IOLs as they are so soft that they cannot be formed without cooling to a very low temperature.

Leading Manufacturers of Artificial Lenses :

Leading Manufacturers include ALCON, AMO (Abbott), Bausch + Lom, HOYA, CARL Zeiss, Ophtec, Rayner, STAAR, Lenstec, HumanOptics, Biotech Visioncare, Omni Lens Pvt Ltd, Aurolab, SAV-IOL, Eagle Optics, SIFI Medtech and Physiol.

Market Share of Artificial Lenses :

The global intraocular lens market was valued at US$ 3.8 billion in 2017 and is expected to witness a CAGR of 7.5% over the forecast period of 2017 to 2025.

Global Intraocular Lens Market Share

artificial lens market

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