Lens coatings are not often the first topic that comes to mind when someone mentions lens design, yet they are just as important as any other aspect of the eyeglasses. These advanced thin-film technologies improve patient satisfaction, optimize visual performance, and extend lens durability. Yet, not all coatings are created equal.
Labs and eye care professionals (ECPs) must balance material compatibility, coating process, wear resistance, and patient lifestyle when recommending or applying coatings. Because even when manufacturers apply coatings with molecular-level precision, wearers only notice a benefit when it solves their optical problems. Understanding coating fundamentals and application best practices will help ECPs prescribe better solutions and labs to avoid coating failures.
Comprehension begins with a better understanding of the differences between various coatings. Essential lens coatings on the market today are as follows:
Anti-reflective (AR) coatings reduce surface reflections on the front and back of lenses. This boosts light transmission, improves night vision, reduces glare from screens or headlights, and enhances cosmetic appearance by making the lenses more transparent.
High-performance professionals, such as surgeons and pilots, benefit from premium AR systems that offer superior clarity and minimal reflections. If a patient works in an environment with airborne contaminants and frequently touches their lenses, they will benefit from the additional oleophobic treatment.
Hard coatings provide a protective layer that improves surface durability during everyday use and cleaning. This makes a lens more resistant to scratches, particularly when working with softer, high-index materials like 1.60, 1.67, or 1.74, which are more prone to surface damage than CR-39. Polycarbonate is also especially delicate and benefits significantly from a hard coating. While most lenses today include this layer, some low-cost CR-39 lenses are still occasionally sold without one, putting them at greater risk of cosmetic defects and reduced clarity over time.
It’s important to always match the scratch-resistant coating to the lens substrate. For example, coatings formulated for Trivex won’t perform the same on polycarbonate. Additionally, a coat needs to polymerize for the exact correct time and temperature, as under-cured hard coats create weak spots that evolve into coating failures months later. Conversely, over-curing can create surface stress that leads to cracking and also produces a yellowish effect. The index of the lacquer needs to match the lens index to avoid the Newton rings effect on the lenses.
Patients with an active lifestyle benefit from protective coatings that can withstand more stress, activity, and cleaning.
UV light-blocking coatings provide additional protection on lenses where substrate absorption may be incomplete, and they allow for UV protection in materials that don't inherently block UV radiation. This helps prevent cumulative UV damage to the eye, like cataracts, pterygium, and retinal issues.
Often, designs combine UV coatings with photochromic lenses. These lenses provide a fast fade-to-black effect when exposed to UV light and quickly clear when UV light is removed.
Blue light filtering coatings are in higher demand as more people spend hours each day on digital devices. These filters have evolved from simple yellow tints to selective filters that target short-wavelength blue light (typically in the 400–455 nm range), which is associated with digital eye strain and potential circadian disruption. LED lights emit the higher-energy blue light at 450 nm.
There are different types of blue-blocking coatings, with some blocking a narrow slice of blue light and others maintaining a broader blocked spectrum:
Mirror coatings reflect visible light and reduce glare in high-brightness environments, such as bright sunlight, water, and snow. The most significant difference between AR coatings is their aesthetic appearance. Mirror coatings have a highly reflective surface and are available in a variety of colors, adding a stylish and personalized touch. Lenses with a mirror coating are popular in sportswear due to their aesthetic appeal.
Coating failures rarely occur randomly. They typically result from process deviations or environmental factors. Understanding common coating problems helps labs implement preventive measures and improve yields.
Adhesion failures manifest as coating peeling or flaking and typically result from improper surface preparation or contamination. Even minor residue on the lens can disrupt coating bonds. Common causes include insufficient cleaning, poor surface etching, both in HC (hard coat) and/or AR (anti-reflective), residual polishing compounds, or inconsistencies in plasma treatment.
Solution: Labs should implement rigorous cleaning protocols and regular maintenance of the plasma system, AR machines, and HC machines.
Variability in spin speed, cure temperature, or dipping lift-out speed can result in patchy coatings. An uneven coating layer leaves weak spots if unprotected or areas more likely to crack if the coating is too thick. This results in less durability and premature wear.
Solution: Check regularly solid contents of the lacquers, lift-out speed, viscosity, etc. Utilize precision-calibrated machinery and conduct regular quality control tests (e.g., Bayer tests) to ensure optimal performance.
Haze, color variation, or reflection anomalies often stem from deposition parameter variations. Chamber contamination, target degradation, or gas flow inconsistencies can create these problems.
Solution: Regular maintenance schedules and process monitoring help prevent degradation in optical quality.
Following strict application protocols and maintaining exacting machine standards is the foundation of high-yield, defect-free coating processes. Labs that consistently achieve premium results typically excel in these areas:
By implementing these controls, labs can dramatically reduce rework, extend coating life, and consistently meet premium optical performance standards.
Superior coating performance isn’t just about equipment. It starts with smart lens design, material compatibility, and consistent process control. That’s why IOT supports labs with technologies that make coating easier, more reliable, and more customizable.
Whether you’re using Neochromes photochromic lenses or Endless Steady progressive designs, IOT’s materials provide excellent adhesion for modern coating stacks. Our lens designs and substrates are developed to support high-yield, high-performance coating applications. IOT partners benefit from:
Tailored coating recipes for AR stacks, blue light filters, and mirror coatings
Validated compatibility with hard coat, AR, and photochromic treatments for highest performance
Whether you’re launching a new mirror series or improving yield on AR stacks, our coating-ready lens platform and technical expertise give our partners a competitive edge in performance and reliability.
Contact us today to find out how we can optimize your coating process together.