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20/20 Optometry - In San Ramon & San Mateo, CA

Ultraviolet light (UV) exposure is increasing throughout the world due to the thinning of the Earth’s protective layer, the ozone layer. The sun is the major source of UV radiation. However, UV light is invisible to the human eye, which is why people underestimate the damage it can cause to our eyes, skin, and immune system.

Over 90% of the UV radiation damage comes from the short wavelength, UVA. These UVA rays can cause cataracts, macular degeneration, wrinkles, and cancer. UVB radiation is associated with sunburns. UVC radiation does not affect the skin and is mostly absorbed by the ozone layer.

UV radiation is divided into 3 categories based on wavelength:

  • UVA (100-290nm)
    • Bifocal/ multi-focal disposable contacts
    • Mono-vision disposable contacts
    • Colored contacts
  • UVB (290-320nm)
    • Most pronounced from 10am-2pm
    • Cannot pass through glass
    • Associated with sunburn
  • UVC (320-400nm
    • Does not affect the skin
    • Can be found in artificial sources such as mercury arc lamps

In addition to UV protection, reducing glare sources is just as important.

What is glare?

Glare is what causes discomfort to the eyes when outdoors, especially when you are around water or reflecting surfaces. There are 3 types of glare sources that attack from different directions. Direct glare comes from above via the sun and from below via reflections. Reflected glare comes in front from flat, shiny, and smooth surfaces (i.e. mirage). Lastly, bounce-back glare attacks from behind you and from the sides.

What are polarized lenses?

Light can be polarized using Polaroid filters. These filters are made of parallel strands that can be oriented vertically or horizontally. When these filters are oriented horizontally in lenses, they absorb the horizontal energy component of light while letting the vertically light component through the lenses. This is why when you wear polarized sunglasses at the beach, it reduces the glare reflection off the ocean water (horizontal energy of light), thus allowing sharp and clear viewing of the ocean water. These lenses are ideal for fisherman, skiers, hunters, drivers, and sailors.

Polarized sunglasses are designed to reduce uncomfortable glare off reflected surfaces such as snow, ice, water, white pavement, black asphalt, hoods and windshields of cars. Polarized lenses, promise wearers enhanced visual comfort outdoors in the various climates, from overcast days to rainy days to sunny days.

So, when you are outdoors, it is a MUST to look good and have 100% UV protection for your eyes. All of our sunglasses offer full protection from UVA and UVB radiation. We specialize in different color filters and can customize lenses to any color. There are mirror coatings and polarization that can be added on to lenses to allow you to have better visual performance.

Below are different lens options to protect your eyes from UV damage:

Color Filters:

  • All have 100% UV protection; but does not reduce glare
  • Can be combined with mirror coatings
  • Most common tints are grey, brown, G-15, yellow and vermillion,
  • Can be any shade of fashion tint; can be customized

Mirror Coating:

  • Eliminates overhead and reflected glare
  • Can be added onto the color filtered lenses or polarized lenses
  • Comes in a large variety of colored mirror coatings

Polarized Lenses:

  • Recommended to all of our patients
  • CAbsorbs reflected glare, which enhances visual acuity, color, and contrast
  • Ideal for drivers, fisherman, hikers, hunters, skiers, sailors, etc.

We can place sunglass lenses in any type of ophthalmic frames (frames made for prescription lenses).

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