understanding your optical lens coatings

November 15, 2022, by Gakari Thomas BSc Optom, Optometrist.

Lens coatings are treatments applied to your eyeglass lenses to improve their durability, function, as well as the appearance.

If you’re thinking about visiting your eye doctor for a new pair of glasses, he or she might recommend a particular lens coating or several coatings depending on your eye problem, your occupation or your lifestyle. To give you a better understanding of what your options are, we will break down the five most common spectacles lens coatings in today’s.

Photo chromatic lens coatings

Photo chromatic lens coatings offer all the benefits of clear lenses indoors and sunglasses outdoors. They usually darken when exposed to sunlight or to ultraviolet light and return to a clear state when indoors, away from UV light or sunlight. They provide visual comfort by automatically adjusting to changing light conditions. They typically take around 30 seconds to fully darken and between two to five minutes to return to a clear state.

ADVANTAGES OF PHOTOCHROMATIC LENSES

• Reduced costs
  
  • buying a single pair of dual purpose photochromic glasses that can provide vision for both indoors when clear and providing sunglasses protection outside is more cost effective than buying two separate pairs.
• Convenience
  
  • You only need to own one pair of glasses for both indoors and outdoors in the sun as opposed to needing to switch between two pairs of regular glasses to sunglasses.
• Eye Health
  
  • Reducing your exposure to the sun’s harmful UV rays can lower the risk of cataracts or other eye/age related problems

·         Reaction Times

o    Although photo lenses reaction from clear to sunglasses is quite quick, typically within 30 – 60 secs, the reversal takes a little longer as much as 5 minutes depending upon the temperature of the lens which could be dangerous if entering a dark room or certainly inconvenient at best.

• Not Dark Enough
  
  • Despite the fact that it works for majority of wearers, but advice must be taken if you are affected by any extreme light conditions.

Anti-reflective Coating/Anti-glare coating

This is a type of optical coating applied to the surface of lenses and other optical elements to reduce reflection.  Anti-reflective coating also called AR improves vision, reduces eye strain and makes your eyeglasses look more attractive. These benefits are due to the ability of AR coating to virtually eliminate reflections from the front and back surfaces of your eyeglass lenses.

With reflections gone, more light passes through your lenses to optimize visual acuity with fewer distractions (especially at night), and the lenses look nearly invisible — which enhances your appearance by drawing more attention to your eyes and helping you make better eye contact with others. Antireflective coatings may be the right option for you if:

• You have difficulty seeing while driving at night 
• You spend a lot of time looking at screens or digital devices
• You’re interested in thinner looking lenses 
• You’re often bothered by reflections when wearing glasses 

The visual benefits of lenses with anti-reflective coating include;

·         sharper vision with less glare when driving at night and greater comfort during prolonged computer use (compared with wearing eyeglass lenses without AR coating).

·         When applied to photochromic lenses, AR coating enhances the clarity and comfort of these premium lenses in all light conditions without reducing their sun-reactive performance.

Blue block/block cut coatings

Blue light is naturally produced by the sun but also by computer monitors, smartphone screens and other digital devices. In addition to these, blue light is produced by LED and fluorescent lights, and compact fluorescent light bulbs. Blue light is essential in maintaining your sleep and wake cycle, mood and keeping your memory sharp.

Blue light is everywhere, while manmade sources of blue light include fluorescent and LED lighting, flat-screen televisions, and the display screens of computers, electronic notebooks, smartphones and other digital devices; our main source of blue light is the sun, and we are most exposed to it when we are outdoors during daylight hours. This is where the most damage occurs and our children are also vulnerable to it since they are more likely to spend a significant amount of time outdoors whether at school or in the playing field.

It contributes to digital eye strain – While this is less dangerous than the effects of the blue light generated by the sun, digital eye strain is something we are all at risk of. Most people spend at least 12 hours a day in front of a screen, though it takes as little as two hours to cause digital eye strain. 

Dry eyes, eye strain, headaches and tired eyes are all common results of staring at screens for too long. Blue light exposure from computers and other digital devices can be reduced with special computer glasses.