Costco Optical (Sunnyvale, CA 94086-5309)

• What's the difference between polycarbonate lenses and Trivex Lenses?

  Polycarbonate lenses are available in a wider variety of lens designs than Trivex lenses. Trivex lenses have a higher Abbe value and may produce sharper peripheral vision with less chromatic aberration than polycarbonate lenses. Trivex lenses have less internal stress and may produce sharper central vision than polycarbonate lenses.

• Why is Anti-reflective coating applied to the back surface of sunglass lenses?

  AR coating is applied only to the back surface of sunglass lenses because there are no cosmetic or visual benefits to eliminating reflections from the front surface of dark-tinted lenses. It eliminates glare from sunlight reflecting into your eyes from the back surface of tinted lenses when the sun is behind you.

• Why does my vision go completely black for a few seconds?

  I often have such problem. It usually happens when I wake up or stand up suddenly. My doctor said it was because Low blood pressure or Low blood sugar. You may see the doctor to find the real cause.

• Are UV levels in the high mountain higher than in the lowland?

  Yes, you will be exposed to more UV rays when in the mountain. The UV rays will increase by 6% to 10% when the altitude increase 1000 meters. So you should have full protection when climbing mountain.

• Do sunglasses in dark tinted color give more UV protection than the light color?

  No, the UV protection has nothing to do with the tinted color. Dark sunglasses can only offer you a mild view when in bright light but they don't absorb more UV rays.

• Does children with slight astigmatism need to wear corrective eyeglasses?

  If your child has slight astigmatism without myopia or hypermetropia, he don't need to get corrective lenses. If your child often gets headache, eyestrain, or distortion of vision while tilting of their heads to see clearly, then the corrective lenses for astigmatism are needed to make the vision clear and comfortable.

• Are non prescription colored contacts safe for eyes?

  They are just as safe as prescription contacts. As long as you wear them in a correct way, there won't be any problem. But you must have the contact lenses fitted an eye doctor because they are in different sizes.

• What should I apply when cleaning glasses with anti-reflective Lenses?

  You should not use the regular detergent liquid as the harsh chemical may damage the anti-reflective coating. There are some special cleaner safe for anti-reflective coating you can get at the optical store or use only products that your optician recommends.

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