The world of ophthalmic lenses has seen significant advances over the years, and undoubtedly one of the most beneficial innovations are advances in coatings (i.e. commonly referred to as anti-reflective treatments). These coatings offer a range of benefits, from greater visual clarity to aesthetic advantages. This article aims to take a brief look at the science and benefits associated with anti-reflective coatings on ophthalmic lenses.

Anti-reflective coatings: what are they and how are they produced?

Anti-reflective coatings are specialised coatings applied to the surface of ophthalmic lenses to reduce glare and reflections. They work by minimising the amount of light that reflects off the lens surfaces, thus allowing more light to pass through the lenses into the eyes. It therefore improves visual clarity and reduces eye strain.

The production of anti-reflective coatings involves a highly technical process that generally takes place in a controlled environment to guarantee the highest quality.

Here are the general steps:

• Cleaning: The ophthalmic lenses are thoroughly cleaned to remove any dust, oils or other contaminants.
• Preparation: The lenses are then prepared for the coating process, often involving a layer of primer to help the coating adhere better.
• Deposition: The actual anti-reflective coating is applied using techniques such as vacuum deposition or sputtering. These methods deposit extremely thin layers of materials such as magnesium fluoride or silicon dioxide on the surface of the lens.
• Layers: Several layers can be applied to achieve the desired anti-reflective properties. Each layer is designed to interfere with specific wavelengths of light, reducing reflections.
• Healing: After the coating is applied, the lenses are cured, usually using ultraviolet light, to harden and bond the coating to the lens surface.
• Quality control: Finally, the lenses undergo quality control tests to ensure that the coating meets all the specifications and performance criteria.

Anti-reflective coatings: how do they work?

The science behind anti-reflective coatings is rooted in the physics of light. When light meets a surface, some of it is reflected, leading to glare and reduced clarity. These coatings are designed to counteract this, allowing more light to pass through the lens, thus improving vision.

The coatings work on the principle of "destructive interference". They are designed to be a quarter of a wavelength thick, so when light reflects off the surface of the lens, it interferes with the light reflecting off the back of the coating. This interference cancels out the reflections, allowing more light to pass through the lens.

Anti-reflective coatings: benefits

Anti-reflective coatings on ophthalmic lenses offer a multitude of benefits that go beyond simply reducing glare and reflections. Here is a brief summary of the main benefits:

Improved visual acuity: 

Anti-reflective coatings can significantly improve visual acuity, especially in low light conditions. This is primarily beneficial for tasks that require high levels of concentration and focus, such as reading small text or working on projects with a high level of detail. They allow more light to pass through the lenses, providing a clearer, sharper image.

Better night vision: 

Driving at night can be challenging due to the glare from headlights and street lights. Anti-glare coatings can certainly reduce this discomfort, making it easier to see and improving safety during night-time driving.

Reduction of "digital eye fatigue": 

With the increased use of digital devices such as smartphones, tablets and computers, digital eyestrain has become a common problem. Anti-reflective coatings can therefore help alleviate the symptoms of digital eyestrain by reducing glare and reflections from screens, thus making it more comfortable to look at digital devices for prolonged periods.

Aesthetic improvement: 

From an aesthetic point of view, the anti-reflective coatings make the lenses more "transparent". It undeniably provides a more natural look, allowing others to see your eyes more clearly and improving your overall appearance.

Improved UV protection: 

Some anti-reflective coatings come with additional UV protection, which provides extra protection for your eyes from harmful ultraviolet rays. This is certainly an extremely important feature for those who spend a lot of time outdoors.

Better colour perception: 

By reducing glare and allowing more light to pass through the lens, anti-reflective coatings can also improve colour perception. This is therefore particularly relevant for tasks and/or professions where good colour perception is key (e.g. photographers, designers).

Greater durability: 

The best quality anti-reflective coatings often include additional layers that make the lenses more resistant to scratches, dust, stains and water (i.e. antistatic and/or hydrophobic coatings). This not only extends the life of your lenses, but also makes them easier to clean.

Versatility: 

They are versatile and can be applied to various types of lenses, including monofocal, bifocal and/or progressive lenses, making them a suitable option for people of all ages and visual needs.

To summarise, anti-reflective coatings on ophthalmic lenses offer a wide range of benefits that improve visual performance, comfort and even aesthetics. Whether you're an avid reader, a driver who does a lot of kilometres at night or someone who spends hours in front of a computer, these coatings can significantly improve your viewing experience.