How to Choose Sunglasses?

The main purpose of wearing sunglasses is to block ultraviolet (UV) rays from the sun. UV rays not only accelerate skin aging and increase the risk of skin cancer but can also cause significant damage to your eyes. Prolonged exposure to strong UV rays may lead to eye problems such as cataracts, macular degeneration, pterygium, and conjunctivitis.

Eye Diseases That May Be Caused by UV Radiation

01. Photokeratitis
Photokeratitis is an acute eye injury caused by intense sunlight, often resulting from UV radiation burns on the cornea. Symptoms include severe eye pain, tearing, a sensation of a foreign body in the eye, conjunctival congestion, swelling, and blurred vision.

02. Retinal Damage
UV rays, particularly long-wave UVA, can penetrate to the back of the eye, causing macular degeneration and other retinal damage. This exposure increases the risk of macular degeneration, especially in older adults.

03. Cataracts
UV rays, with wavelengths between 290–400 nanometers, can cause cross-linking and aggregation of soluble proteins in the lens, leading to lens aging or cloudiness, which can eventually result in cataracts.

04. Pterygium
UV radiation can cause degeneration of the conjunctival tissue, resulting in pterygium. This condition involves tissue growth from the corner of the eye toward the pupil, which can impair vision in advanced stages.

How to Choose the Right Sunglasses?

When selecting sunglasses, consider the following factors:

1. Lightweight and Comfortable to Wear

   • They should filter 75%-90% of visible light and avoid causing visual distortion or image distortion.

2. UV Protection

   • Look for sunglasses that block 95%-100% of UVA (320-400nm wavelength) and UVB (280-320nm wavelength) rays.

3. Lens Quality

   • Check the lenses under a light source. The edges of the lenses should not show any distortion or wavy patterns.

4. Lens Color

   • Darker lenses are not always better. Opt for medium-depth colors. Shades like gray, brown, and green are usually more suitable.
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Lens Color and Their Effects:

• Gray Lenses

  • Absorb infrared and most UV rays effectively. They reduce light intensity without altering color perception.

• Brown Lenses

  • Absorb blue light effectively and enhance contrast between the sky and objects on the ground, creating a softer visual experience. They are helpful for individuals with red weakness but may worsen color perception for those with green weakness.

• Green Lenses

  • Absorb infrared and most UV rays. However, they may alter some colors, making them unsuitable for individuals with color blindness.

• Yellow Lenses

  • Block harmful blue light and enhance visual clarity, especially by increasing contrast sensitivity. They help maintain clear vision during fast motion but may affect night vision and the ability to distinguish traffic lights.

• Red Lenses

  • Enhance contrast and are particularly effective at blocking shorter wavelengths of light. They are ideal for environments with intense sunlight, such as skiing conditions.
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• People Who Should Avoid Wearing Sunglasses for Extended Periods

  1. 01. Children Under 6 Years Old

     • The visual function of children under 6 is not yet fully developed to adult levels. Prolonged use of sunglasses may lead to amblyopia (lazy eye).

  2. 02. Glaucoma Patients and People Over 40 Years Old

     • As people age, the lens nucleus begins to harden, and the cortex starts to swell, which can cause the anterior chamber of the eye to become shallower. Glaucoma patients often have shallow anterior chambers and narrow angles as well.
     • Wearing sunglasses reduces the amount of visible light entering the eye, causing the pupils to dilate. This dilation can block the pathways for aqueous humor drainage, increasing the risk of acute angle-closure glaucoma.

  3. 03. Conditions That Should Avoid Sunglasses

     • Individuals with glaucoma, color blindness, and night blindness are not recommended to wear sunglasses.

     • How to Care for Sunglasses

       1. 01. Folding

          • Follow the standard folding sequence, usually folding the left temple first, then the right.

       2. 02. Removing and Wearing

          • Always use both hands when putting on or taking off sunglasses to avoid uneven pressure. Using one hand can easily deform or even break the frame.

       3. 03. Cleaning

          • Avoid dry wiping as it can scratch the lenses. Instead, use a specialized cleaning solution, spray it on the lens surface, and use a tissue to absorb the moisture before wiping with a microfiber cleaning cloth. If rinsing with water, quickly dry the lenses with tissue or a cleaning cloth to avoid water stains.
          • Note: Do not use ultrasonic cleaners, as they may damage the sunglasses' UV protection and shading effects.

       4. 04. Adjusting

          • After wearing sunglasses for some time, the frame may deform, putting pressure on your nose and ears, and the lenses might loosen. Regularly adjust and fix the frame to ensure a comfortable fit and secure lenses.

       5. 05. Storing

          • Always place the sunglasses with the convex side of the lens facing up to avoid scratching. Keep them away from sharp or hard objects.
          • Avoid storing sunglasses in high-temperature environments, as excessive heat can deform them, especially plastic frames that are not heat-resistant. Prolonged exposure to sunlight can cause the frame to fade or discolor due to heat and light.

       Every product has a lifespan, and frequent handling of sunglasses may result in inevitable scratches or wear. Deformation may also occur over time due to aging. If the sunglasses are damaged or their shape affects the wearing experience, repair or replace them promptly. Do not ignore these issues, as optical parameter deviations can harm your eyes.