Intraocular lens manufacturing with injection moulding
What is an intraocular lens (IOLs)?
An intraocular lens (IOL) is a small, prosthetic lens implanted in the eye. Since the early 1980s, IOLs have been used as an “upgrade” to reduce the need for glasses or contact lenses, or as part of cataract surgery to replace cloudy natural lenses. Constructed with two plastic side struts that support the lens within the eye, IOL implants are effective in treating vision issues such as myopia (nearsightedness), hyperopia (farsightedness), presbyopia (age-related farsightedness), and astigmatism (abnormal eye shape).
Silicone, acrylic, or other plastic compositions are commonly used to make the majority of IOLs. Additionally, a unique substance is applied to them to assist shield eyes from the sun’s damaging ultraviolet (UV) rays. Some types of IOLs include aspheric IOLs, toric IOLs, accommodating IOLs, phakic lenses, multifocal IOLs and monovision.
According to a recent study, the intraocular lens market is predicted to increase at a compound annual growth rate (CAGR) of 7.25% from 2022 to 2028, from its estimated valuation of USD 5.14 billion in 2022 to USD 7.82 billion.
How is intraocular lens (IOLs) made?
The manufacturing of intraocular lenses (IOLs) is a highly regulated process to ensure patient safety and product quality. IOL manufacturers must comply with industry standards, legal requirements, and regulatory guidelines to market their products. The typical IOL manufacturing process includes the following stages:
- Selection of Material: A variety of materials, including silicone, acrylic, and hydrophobic acrylic, can be used to create IOLs. The surgeon’s preference, lens purpose, biocompatibility, and flexibility all play a role in the material selection process.
- IOL Design and Mould Design – Manufacture: The lens’s curvature, thickness, and other characteristics are key factors involved in the design stage, which will hence impact the mould design and mould manufacture.
- Fabrication: Precision injection moulding methods are normally employed in the production of IOLs, especially for mass production projects.
- Surface Coatings: To improve optical qualities, lessen glare and increase biocompatibility, many IOLs have unique materials coated on them. Hydrophobic coatings aid in keeping water droplets from sticking to the surface of the lens.
- Quality Control: Throughout the production process, strict quality control procedures for medical products are required, including but not limited to optical testing, validation, and inspections. This step is essentially important, especially if IOLs are sold in global markets.
- Sterilisation: In order to get rid of any possible impurities, IOLs are put through sterilisation procedures after production. Ethylene oxide gas and gamma radiation are two frequently used sterilising techniques.
- Packaging: In order to preserve their sterility until implantation, IOLs are meticulously packed in sterile, sealed containers.
Mould design, manufacture, and injection moulding are critical to the successful mass production of intraocular lenses (IOLs). Each IOL mould is produced with exceptional precision, as any imperfections in the mould will be transferred to the final lenses during the injection moulding process. Therefore, prior to mass production, moulds undergo rigorous testing to ensure that the injection-moulded lenses meet the required design specifications without error.
In contrast to mechanical components, the injection moulding of intraocular lenses (IOLs) requires specialised expertise, with micro-moulders needing experience in handling extremely small parts that have specific packaging and handling requirements. Several factors influence the reproducibility of IOLs during mass production, particularly within the micro injection moulding process. Dimensional stability is crucial, as incorrect material choice can result in moulded lenses that are not stable, leading to shrinkage and compromised effectiveness over time. Therefore, close collaboration between designers, product developers, mould makers, and injection moulders is essential to optimise design, tooling, and production processes. Partnering with an injection moulder that has in-house tooling capabilities can enhance project efficiency, improve communication, and reduce production time.
Before being released for consumer use, moulded intraocular lenses (IOLs) undergo additional processes such as lapping, trimming, and polishing to remove any protrusions, pits, or edge burrs that could cause eye irritation. It is crucial that all moulding and post-moulding procedures ensure the elimination of contaminants, including plasticisers, mould release agents, lubricants, and antioxidants, to prevent any potential contamination of the lens.
In addition, as the lens’s ability to operate may be impacted by both human and airborne pollutants, such as germs and dust from raw materials, the production of ultra-precision moulds and the injection moulding process are conducted within strictly controlled environments, for example ISO class 7 or 8 cleanroom environments, to ensure the highest medical quality.
With more than 20 years of experience in micro mould toolings and injection moulding, Micro Systems can support your IOL projects from the very first step, ensuring a smooth transition from prototyping to mass production. We have the latest technology in micromachining and micro injection moulding, with top-of-the-field designers and engineers, and world class facilities in the UK and Singapore.
Contact us today to discuss your IOL project!
