With the wide variety of optional coatings that are available for lenses these days, it’s not always easy to determine which ones are entirely necessary.
What are Necessary Lens Coatings?
Do you really need scratch-resistance? Under what conditions does anti-fog become a useful option? Does a mirror coating enhance the light filtering properties of a lens?
The answers you seek are often related to two factors: the conditions under which you use your lenses, and the type of lens material they’re made of. With these guidelines in mind, let’s examine a few of the common coating options and the benefits they provide.
- Scratch Resistance Coating – A scratch resistant coating is often applied to surfaces that are not inherently scratch-resistant, like CR-39 plastic, polycarbonate, or Trivex. It adds a barrier of protection that hardens the surface against both large gouges and smaller scratches, which can build up and crisscross to add a hazy appearance to lenses. If your lenses are formed from any material other than glass, a scratch-resistant coating will increase their productive lifespan.
- Anti-Reflective Coating – Anti-reflective coatings eliminate the distracting glare that can be produced by light when it reflects through your lenses. Anyone subjected to direct or indirect reflections – especially those who spend a lot of time around computers and electronic monitors of any type, suffer from eye strain, or who drive at night – will likely enjoy the benefits of glare reduction. Due to the high reflective properties of high index lenses, an anti-reflective coating is recommended, and is practically mandatory for high index lenses made of glass.
- Anti-Fog Coating – An anti-fog coating works by chemically affecting the adhesion of water molecules, preventing them grouping into larger clusters that can impair vision. If your glasses are frequently exposed to temperature changes or humid conditions, you’ll likely want an anti-fog coating to help combat condensation. The same goes for anyone who engages in strenuous activities such as physical labor, participation in sports, or exercise. Any activity that causes your body temperature to fluctuate will likely lead to lens fogging.
- Ultraviolet Light (UV) Protective Coating – UV light is invisible to the human eye but can, in excess, cause retinal burning and scarring. Most sunglasses are already designed to block a high level of UV radiation; other lenses, depending on their function or lens material, may also block some UV rays. If your lenses do not specifically state their UV screening level and you spend time outdoors, an additional UV coating will offer protection and piece of mind.
- Mirror Coating – this coating on lens exteriors gives them a reflective mirror finish and is available in different colors. It’s an aesthetic choice but also reduces the amount of light passing through the lenses, effectively acting as a tint.
The type of coating or coatings you opt for will vary based on your personal tastes, your activities, and your lens choices. Use the above as a guide to help determine which coatings will come in handy and which ones you can skip.