Sunglasses are worn mainly to eliminate the discomfort and disabling effects of bright light, and to protect against ultraviolet and infrared radiation. The need for sunglasses varies because people differ in the extent to which they tolerate bright light and in their occupational and recreational activities.
When sunglasses should be worn
Sunglasses are designed for outdoor daytime wear in bright sunshine or where there is glare. They should he worn when bright sunlight causes watering of the eyes, squinting or excessive blinking.
Sunglasses are essential during periods of prolonged exposure to sunlight. Besides visible light, sunlight contains two powerful invisible forms of radiation: ultraviolet and infrared. Continued exposure to these, especially ultraviolet, can cause serious eye damage.
Optometrists recommend that people who spend most of their time outside or who work near snow, water or sand should wear sunglasses that filter out both ultra violet and infrared rays. Because the effects of exposure to UV accumulate over a person’s lifetime, it is important for children as well as adults to wear eye protection.
Sunglasses should not he worn at night — particularly not while driving. This is because in the dark they can reduce vision to dangerously low levels. A driver could miss seeing a pedestrian or a parked car.
If you feel that you need to wear sunglasses continually for comfort, you should consult our optometrist; you may have a problem with your eyes or vision.
Differences between types of sunglass lenses
- Tinted Made of glass or plastic. Tinted lenses come in a variety of shades. To be effective they should screen out 70 to 90 per cent of available visible sunlight. Grey tints do not affect the colours you see and are the best choice where colour accuracy is important. Glass lenses with green tints are usually best at filtering infrared. Lightly tinted fashion lenses do not screen out sufficient light to be properly classified as sunglasses.
- Polarising Usually plastic polarising lenses are effective in combating the glare caused by light reflected from the road or from water. They screen out ultraviolet rays. Prescription Polaroid lenses are also available. Drivers should note that dark blotches appear on some safety windscreens when looking through polarising sunglasses.
- Photochromic Commonly called sun sensitive or light sensitive lenses, photochromic lenses darken or change colour as the sun gets brighter. To ensure sufficient darkening in sunlight only quality photochromic lenses should be worn, and 5 to 90 per cent of available sunlight should be screened out. Photochromic lenses achieve full effectiveness after a few weeks of wear. The majority of photochromic lenses do not work in cars.
- Reflecting A thin metallic coat is combined with tinted lenses to produce a mirrored appearance. They are designed for wear under intense glare such as sunlight reflected from water or snow. Some absorb both ultraviolet and infrared rays.
What to look for in sunglasses
Make sure that the lenses conform to the Australian Standard that specifies that the glasses are manufactured from quality ophthalmic materials, which:
- screen out ultraviolet light,
- are ground and polished to be free of distortion and imperfection,
- are perfectly matched in colour and absorptive power,
- match your prescription if you usually wear spectacles out of doors,
- are large enough to provide ample protection, and
- are made from the material best suited to your needs.
Plastic lenses are generally more impact resistant than glass, and lighter in weight. However, they scratch more easily unless they have a scratch-resistant coating and, unlike some glass lenses, do not filter out infrared rays.
Check that the frame:
- is of sturdy construction, and
- does not interfere with side vision
Sunglass Standards became law in Australia on 1 October 1985. All sunglasses sold in Australia have to pass less UV than visible light. In practice, this means that they all are 100% UV. We have a UV tester that will tell you how effective your sunglasses are at blocking UV.
At Penrith Spectacles, we have many brands of sunglasses. Here are a few:
Rodenstock have been in the optical industry for over 100 years
If you have prescription glasses already, why not try fitovers?