Authors: Wendy Strobel*, Jennifer Fossa, Carly Panchura, Katie Beaver, and Janelle Westbrook
Contributors: Stephen Bauer, Sajay Arthanat, Joe Lane, Deborah Gilden, & Bill Crandall
This is a publication by the Rehabilitation Engineering Research Center on Technology Transfer, which is funded by the National Institute on Disability and Rehabilitation Research of the Department of Education under grant number H133E9800025. The opinions contained in this publication are those of the grantee and do not necessarily reflect those of the Department of Education.
University at Buffalo
Center for Assistive Technology
Rehabilitation Engineering Research Center on Technology Transfer
The Industry Profile on Technology for Visual Impairment
This book may not be reproduced in any form without the permission of the publisher. Individual pages may be reproduced with proper acknowledgement.
This is a publication of the Rehabilitation Engineering Research Center on Technology Transfer, funded by the National Institute on Disability and Rehabilitation Research of the Department of Education under grant number H133E030025. The opinions contained in this publication are those of the grantee and do not necessarily reflect those of the Department of Education.
Editors: Wendy Strobel*, Jennifer Fossa, Carly Panchura, Katie Beaver, and Janelle Westbrook Contributors: Stephen Bauer, Sajay Arthanat, Joe Lane, Deborah Gilden, & Bill Crandall
*Wendy Strobel, the communicating author can be reached by phone at 716.829.3141 x 140 or via e-mail at firstname.lastname@example.org
Rehabilitation Engineering Research Center on Technology Transfer
Center for Assistive Technology
State University of New York at Buffalo
Kimball Tower, Room 322, 3435 Main Street Buffalo, NY 14214-3079
The Industry Profile on Technology for Visual Impairment is a reference document for technical and clinical research, product development, market analysis and segmentation, and general education. The Industry Profile includes market segments size and descriptions, clinical issues, technology overview, products, reimbursement sources, manufacturers, trade associations, and related publications. It is intended to give the reader a sense of the impact imposed by visual impairments in the United States. This document is also available in an accessible format on our website at http://cosmos.ot.buffalo.edu/t2rerc/
Each entry in the Table of Contents has a specific intent. The document begins with a discussion of the Anatomy and Physiology of the Eye, intended to give the reader a clear understanding of the various parts of the eye and the functions that they control in the acquisition and processing of visual information. Following is a section on Visual Assessment, a compilation of various vision tests and reasons that they may be performed, methods of testing, and possible outcomes. The Eye Care Professionals section provides a breakdown of care providers who assist persons with visual impairments, and an explanation of the services that they are trained to offer.
The section on Visual Impairments, Causes and Treatments differentiates the major causes of adult blindness from the major causes of childhood blindness. It outlines symptoms, causes, and treatments for a number of visual impairments and provides information on prevalence. The section on Demographics gives a sense of how many people currently have specific limitations and thereby, how many may benefit from the development of a new technology.
The section on Prevalence of Visual Impairment in the United States provides an overview of the impact on Visual impairment in this country. Market Growth provides the reader with a sense of how prevalence numbers will change over the next thirty years.
The Technologies section outlines four categories of assistive technology utilized by persons with visual impairments: 1) technologies to assist with activities of daily living, 2) computer access technology, 3) access to graphics, and 4) wayfinding technology. It defines, provides examples of, and lists potential applications for each type of technology.
The section Assessment of Needspresents a delivery model of the steps involved in assigning an appropriate technology to an individual. Legislation presents recent developments regarding equal access for persons with visual impairments. The Funding Sources section outlines the types of funding available to persons with visual impairments. Also included is contact information for a number of specific organizations, as well as a brief description of individual services offered by each Source of Financial Aid for Eye Care.
The various appendices of this document contain contact information for a wide range of manufacturers, related associations, and service providers. In addition, a listing of relevant publications is included to direct the reader to more comprehensive authorities on a number of subjects.
The mission of the Rehabilitation Engineering Research Center on Technology Transfer (T2RERC) is to improve the variety, quality, and choice of products available in the marketplace to benefit persons with disabilities. The Demand Pull Project fulfills this mission by addressing needs within a targeted market. The following areas have been the focus of earlier projects: wheelchair and scooter technology, hearing technology, and alternative and augmentative communication technology. Under the Demand-Pull Project on Technology for Visual Impairment an industry profile has been compiled to facilitate the development and introduction of new products into the marketplace to benefit people with blindness and low vision.
The Industry Profile provides a snapshot of the current state of practice in the field of visual impairment. We have included the most current data available. Please consider a few important points as you read through this document:
A significant majority of the people who report visual impairments are over the age of 65.
Only 10% of people with visual impairments are able to read braille (American Foundation for the Blind, 2003).
There are an enormous amount of services and technologies in the United States for people who need them, yet many do not know they exist.
Many service providers who work in the field of visual impairment are either not aware of or are not sharing vital information about assistive technologies that can positively impact the lives of their customers.
Visual impairment is a growing concern in America as the number of people affected by vision loss continues to grow.
New and innovative technologies that provide people with visual impairments with equal access to employment, education, and community are being introduced through technology transfer on a regular basis.
We thank everyone who has contributed to the research, with special thanks to the Smith-Kettlewell RERC for Blindness and Low Vision for their help. Within each project, the T2RERC partners with the corresponding RERC and one of the six regions of the U.S. Federal Laboratory Consortium (FLC). The partner RERC has knowledge of relevant research and reference materials, consumer needs, and products in the marketplace. The collaborating FLC Region provides access to experts in core technologies. The partner organizations for the Demand-Pull Project on Technology for Visual Impairment are the Smith-Kettlewell RERC for Blindness and Low Vision, and the Far West Region of the Federal Laboratory Consortium.
Your comments and feedback are very welcome and will help us improve the quality and completeness of future profiles. Please forward any suggestions you may have to email@example.com.
Anatomy and Physiology of the Eye
Figure 1: Diagram of the human eye identifying the various segments described below.
The protective outer layer of the eye, sometimes referred to as the “white of the eye” is called the sclera and it maintains the shape of the eye. The front portion of the sclera, called the cornea, is transparent and allows light to enter the eye. The cornea is a powerful refracting surface, providing much of the eye's focusing power (Cassin and Solomon, 1997). Attached to the sclera are six extraocular muscles responsible for movement of the eyes (Bianco, 2002). The choroid is the second layer of the eye and lies between the sclera and the retina. It contains the blood vessels that provide nourishment to the outer layers of the retina (Cassin and Solomon, 1997). The iris is the part of the eye that gives it color. It consists of muscular tissue that responds to surrounding light, making the pupil, or circular opening in the center of the iris, larger or smaller depending on the brightness of the light (Pachler and Rizun, n.d.).
Light entering the pupil falls onto the lens of the eye where it is altered before passing through to the retina. The lens is a transparent, biconvex structure, encased in a thin transparent covering. The function of the lens is to refract and focus incoming light onto the retina for processing (Moorfields Eye Hospital, 2002).
The retina is the innermost layer in the eye. It converts images into electrical impulses that are sent along the optic nerve to the brain where the images are interpreted. The retina can be compared to the film of a camera. It is composed of light sensitive cells known as rods and cones interconnected by a complex mesh of neurons that provide early stage visual processing. Rod cells are primarily in the outer retina, do not discriminate colors, have low spatial resolution, support vision in low light (“night vision”), are sensitive to object movement and provide peripheral vision. Cone cells are densely packed within the central visual field, function best in bright light, process acute images and discriminate colors (Montgomery, 2002).
The macula is located in the back of the eye, in the center of the retina. Within the macula is an area called the fovea centralis. This area contains the highest concentration of cones, produces the sharpest vision, and is used to see details clearly (Moorfields Eye Hospital, 2002).
The inside of the eyeball is divided by the lens into two fluid-filled sections. The larger section at the back of the eye is filled with a colorless gelatinous mass called the vitreous humor. The smaller section in the front contains a clear, water-like material called aqueous humor (Discovery Fund for Eye Research, 1999). A circular canal, called the Canal of Schlemm provides a drainage system for the aqueous humor from the eye into the bloodstream. Blockages in the Canal of Schlemm are believed to be contributing factors in the development of glaucoma (Bianco, 2002).
The conjunctiva is a mucous membrane that begins at the edge of the cornea and lines the inside surface of the eyelids and sclera, which serves to lubricate the eye. Inflammation of this membrane results in conjunctivitis, commonly known as pink eye (Bianco, 2002; Cassin and Solomon, 1997).
The Lighthouse International is a leader in the development of rehabilitation services, education, research, prevention and advocacy in visual impairment. They provide the following definition of visual impairment (2001):
“Vision is a complex sense, encompassing the ability to perceive detail (acuity), color and contrast, and to distinguish objects. These capacities can diminish naturally with age. While most visual changes can be corrected by glasses, medicine or surgery, visual changes caused by eye disease, poor health, or injury can cause permanent vision loss. If the loss is total, the result is blindness. If it is partial, the result is a vision impairment known as "low vision." A person with low vision has severely reduced visual acuity or a significantly obstructed field of vision — or both.”
Vision loss can occur in varying degrees in the following areas: (1) impairment to central vision resulting in blind spots, poor acuity and difficulty or inability to see fine detail and perceive color, (2) impairment of the cornea or lens resulting in blurred vision and sensitivity to glare, (3) impairment of peripheral vision leaving only the ability to see the center of the normal visual field (tunnel vision), thereby limiting the ability to perceive motion, see an entire picture at one time, and see in low light, (4) loss of vision in other parts of the visual field, including the left, right , upper or lower parts of the visual field, or (5) a combination of any of these condition.
Since vision changes can occur without notice, eye examinations are recommended on a regular basis. The minimum recommended frequency of examination for those at low risk for vision loss, as recommended by the Canadian Association of Optometrists (2003), is as follows:
Infants and toddlers (birth to 24 months) – initial exam at or before 6 months of age
Preschool (2 to 5 years) - at age 3, and prior to entering elementary school
School age (6 to 19 years) - annually
Adult (20 to 64 years) - every one to two years
Older adult (65 years and older) - annually
A comprehensive eye examination evaluates general eye health and may result in a corrective lens prescription, if appropriate. A number of tests may be conducted to examine the external and internal parts of the vision system including the eyelashes, eyelids, conjunctiva, iris, lens, cornea, pupils, extra-ocular muscles, blood vessels, optic nerve and the retina. Vision problems including glaucoma, cataracts and corneal diseases, as well as ocular changes associated with diseases such as diabetes, high blood pressure and neurological disorders will be assessed (EyeHealth Northwest, 2003). The following is a description of some common eye tests and procedures.