Sunglasses serve a greater purpose than simply reducing sunlight. Beyond visual comfort, they provide crucial protection and optimize visual function, especially for the visually impaired. It's not just about light…
Telescopes and binoculars are multi-lens devices that are used by the visually impaired, offering enhanced viewing capabilities for distance. These devices can also be tailored or modified to assist with…
Sunglass lenses should be able to:
If you have read the other posts on Lens Technology, what you may have realized is that sunglasses are more than a tint used to decrease the amount of sunlight that gets to your eye. While visual comfort is important, sunglasses are also about protection and optimizing visual function. It is not just about how much light is transmitted through the lens, but how the lens performs. Ideally, they should enhance vision. Here’s how: (more…)
Decreasing light levels with a tint may give a greater level of visual comfort, but may not offer enough protection against wavelengths of light known to be harmful to the sensitive tissues of the eye. Specifically, protection from the high energy, damaging, short wavelength UV light. Lens materials such as plastic and poly carbonate have some UV absorbing capability (see Lens Materials). (more…)
Tints not only vary in color, but also vary in transmissibility. The amount of light that is transmitted is the amount of light allowed to pass through the lens. The darkness of the tint does not indicate it’s capability to protect against harmful UV light.
While you may think that sunglasses are just glasses with a tint, but protecting the eyes requires more than just a tint. The tint decreases the amount of light that reaches your eyes. Generally, the darker the tint, the less light is transmitted (passed through) the lens. Someone who is outdoors and needs to decrease the brightness of sunlight, will choose a lens with low transmittance. Keep in mind, the darkness of the tint does not indicate it’s capability to protect against harmful UV light. (more…)
Polarized lenses have a molecular structure which gives it the ability to reduce glare. Glare is light reflected and scattered off of a surface that is brighter than the surrounding light. Glare can decrease our capability to see clearly and can cause visual discomfort. (more…)
Anti-reflective coating is applied to the surface of the eyeglass lens to optimize vision by reducing glare. Ideally, it should be applied to both the front and back surface of the lens for maximum benefit.
It serves several purposes: (more…)
Prism in lenses is not so much something ‘in’ the lenses, but it is actually how that lens is constructed, which is typically referred to as being ‘ground in.’ The presence of prisms will be seen as a thicker edge by the wearer. The thicker edge is where the base of the prism is located, and is opposite to where the image is to be shifted.
Lens materials, lens designs, and add-on tints are all options available to help you design your eye wear. Prisms are not offered as an option, but are a part of your eyeglass prescription. (more…)
‘Aspheric’ refers to a type of lens design. It is recommended for those high-powered reading and magnifying eyeglasses.
There is also an aspheric design for those who are very near-sighted and wear ‘coke-bottle’ lenses in their eyeglasses. You may also see hand-held and stand magnifying lens that are aspheric in design. (more…)
You think that it should be simple: aren’t all eyeglass lenses clear plastic: Most are, but there are several types of plastic, each with features that differentiate them by how they function. There are also glass lenses, which are only occasionally a first choice.
Once the eye doctor has written up a prescription for eyeglasses and you are sitting in front of the optician, he or she will begin asking you questions about lens-type preferences. The optician will often give suggestions as to the best lens material for you based on the prescription. They will usually educate the consumer as to the features that will be beneficial. Here are the basic types of lens materials: (more…)