Information for the Visually Impaired

Lens Technology: Prisms

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…)

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Lens Technology: Aspheric lenses

‘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…)

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Eyeglass Technology: Lens Materials

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…)

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Low Vision Devices are More Than Just Magnification

Low vision devices come in many forms. They can be optical, such as lenses, eyeglasses, and telescopes, electronic devices, such as video magnifiers, CCTVs, and digital assistants, or objects adapted for use by those who are unable to see details, such as those things that give audible cues or are labeled in large print. (more…)

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Eyeglasses Used for Magnification

Near vision can be improved by strengthening the eyeglass prescription to magnify. The advantages of high powered reading glasses are that they can have a larger field of view and are hands-free.

Adapting to low vision should start with a comprehensive eye examination to optimize your vision with the best eyeglass prescription. This prescription is for distance and near viewing. What defines those with low vision is that even with the best prescription, they are unable to get perfect vision.  More is needed. (more…)

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Hand-held Magnifiers

Hand-held optical magnifiers come in many styles, sizes, and magnification powers. Commonly, they are sold as either round or rectangular clear lenses, with a handle. Other types include small pocket magnifiers and a plastic ‘card’ style.

Hand-held magnifiers
Hand-held magnifiers

The actual amount of magnification that you get form a hand-held magnifier is variable and dependent on how you use it. Optical lenses have an optical property called focal length. If the lens is held above the page, at the focal length, you will get the magnification indicated by the manufacturer. If you hold it closer to the page, at a distance less than the focal length, you will get less magnification.  Magnification is also dependent on whether you wear your distance glasses, your bifocals, or no glasses at all. (more…)

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Electronic Low Vision Aids:

Video Magnifiers and CCTVs

Video magnifiers and CCTvs vary in size, but are basically a camera, a screen to view what the camera ‘sees’, and a light source. The size will determine its usefulness for various reading tasks.  While most video magnifiers are hand-held and portable, most CCTV units requires its own space on a desktop. 

Both have some of the same features:

  • More than one magnifying level;
  • True color mode is seeing the colors on the screen as they appear on the page;
  • Inverse mode is the capability to reverse print to white on a black background; and
  • Other color modes, such as yellow print on either a blue or black background, or the reverse which would be blue or black print on a yellow background.

Those are the similarities. Here are the differences: (more…)

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Low Vision Aids for the Visually Impaired

The low vision aids can be divided into 3 basic  categories:

  1. Objects modified for use by the visually impaired;
  2. Optical devices; and
  3. Electronic technology.

Browse any of the internet sites, like Amazon or  Independent Living, Aids and you will see a vast array of devices called ‘low vision aids.’   Low vision aids can be anything from bold lined paper to the desktop CCTV (closed circuit television).

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Introduction to Assistive Technology for Low Vision

Low vision aides  are associated with high powered eyeglasses and magnifiers.  Assistive technology refers to  low vision aids, both high tech and low tech. They are devices and products designed to level the playing field for those with visual impairments remain active, engaged, and independent.

 With assistive technology, students can keep up with their classmates and move efficiently through the higher levels of education.  The working visually impaired can maintain employment with the right assistive technology in place. When we are not working or going to school, assistive technology helps with activities of daily living. (more…)

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