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Whittier Union High School District

Low Vision

California Department of Education
1430 N Street
Sacramento, CA 95814

http://www.cde.ca.gov/re/pn/sm/lowvision.asp

Page Generated: 6/8/2010 11:46:52 AM

 

Low Vision Information

Definitions, causes, devices, assessment, and resources.

 

Definitions 

Low vision is a term used to describe a permanent and significant loss of visual function including either visual acuity (the ability to see detail), visual field (the ability to see a large area of about 175 degrees) or both. Low vision cannot be corrected with conventional glasses, contact lenses, surgery or medication.

Low vision is not to be confused with legal blindness which is defined in federal law for use by the Social Security Administration or Internal Revenue Service as central visually acuity of 20/200 or less in the better eye after best possible standard correction or visual field of no greater than 20 degrees. A central visual acuity of 20/200 means that a person can only see visual detail such as a letter or word at a distance of 20 feet that can be seen by a normally sighted person at a distance of 200 feet. LEGAL BLINDNESS IS NOT NECESSARILY THE SAME AS TOTAL BLINDNESS. All totally blind people are legally blind, but those legally blind persons who have some usable vision are considered to have low vision. There must be some usable vision remaining to be considered low vision.

Legal Blindness is defined in federal law for use by the Social Security Administration or Internal Revenue Service as central visual acuity of 20/200 or less in the better eye after best possible standard correction or visual field of no greater than 20 degrees. A central visual acuity of 20/200 means that a person can only see visual detail such as a letter or word at a distance of 20 feet but that can be seen by a normally sighted person at a distance of 200 feet. LEGAL BLINDNESS IS NOT NECESSARILY THE SAME AS TOTAL BLINDNESS. All totally blind people are legally blind, but legally blind persons who have some usable vision are considered to have low vision. There must be some usable vision remaining to be considered as low vision.

To be eligible for special education, a pupil must have a visual impairment which, even with correction, adversely affects a pupil's education performance. The term visually impaired includes for educational purposes: 1) functionally blind students who because of the severity of their visual impairment rely basically on senses other than vision as their major channels for learning; and 2) low vision students who use vision as a major channel for learning. A visual impairment does not include visual perceptual or visual motor dysfunction resulting solely from a learning disability.

O C.F.R. 404.1581 (1988)

 

Causes

Low vision may be genetic and begin at birth such as albinism; it may be developed during the lifetime due to such an eye disease as macular degeneration; or it may be caused by an accident, such as optic atrophy due to a brain injury. Some eye diseases, such as aniridia, are stable, while others progressively deteriorate, often resulting in low vision followed by total blindness such as diabetic retinopathy. It is estimated that approximately .4 million persons in California have low vision. Only about 1 of 10 visually impaired persons are functionally blind and have no useful vision.

 

Low Vision Devices

Collaboration among all professional education and eye care staff in providing coordinated, comprehensive services is critical to achieving the greatest success for students with visual impairment.

Unfortunately, many eye doctors are not aware of the availability of devices designed to help low-vision students use their residual vision more effectively. Not enough attention is focused on individuals with visual impairments because they comprise only a very small minority of the population that requires eye care.

Students with visual impairment and their families are often discouraged after being told by an eye doctor that no more can be done to help them use their residual vision more effectively. Showing students and their families such nonprescription devices and materials as those contained in the ENVISION I & II kits from APH will not only raise the level of awareness of the existence of a variety of low-vision devices but also provide the necessary motivation and demonstration that something can be done in many cases.

Low vision devices work in one of several ways:

  • Control the focus or image clarity
  • Control illumination and contrast
  • Control magnification or size of the image on the retina


Magnification can be achieved by:

  • Relative distance (moving closer to the object)
  • Relative size (physically enlarging the object)
  • Optical (enlarging the image on the retina by passing it through a lens or group of lenses)
  • Electronic projection magnification (enlarging the image on the retina, using projectors and/or computers)


Some generalizations about optical devices are:

  • The larger the lens, the weaker the magnification; and the larger the area one sees at one time through the lens, the larger the depth of focus that makes the working distance less critical.
  • The smaller the lens, the stronger the magnification; the smaller the area one sees at one time through the lens, the less the depth of focus that makes the working distance more critical.
  • The closer the lens is held to the eye, the greater the area the user will be able to see through the lens, regardless of the magnification.
  • Plastic is lighter than glass, but it scratches more easily.

The low-vision student should understand the characteristicsadvantages and limitationsof the devices based on the following factors:

  • Working distance
  • Field of view
  • Depth of focus
  • Weight
  • Cosmetic appearance
  • Style of the device (hand-held, head-borne, etc.)

The devices will be more readily accepted by the low-vision student when:

  • The device enables the student to do what he or she wants to do.
  • The device appears as conventional as possible so it doesnt attract attention.
  • The device is easily portable so that it can be used wherever the student goes.
  • The student is highly motivated and believes success is possible.
  • There is follow-up training to reinforce successes as the student is learning to use the device effectively.

The instructional model should include:

  • Routine to establish a pattern
  • Success-oriented training
  • Short learning periods that gradually increase in duration
  • Use of relevant, age-appropriate, high-interest-level activities

Learning sequences vary, but generally with respect to magnifiers, the user should do the following:

  • Locate the material to be read
  • Adjust the angle of lighting
  • Hold the device and position the material in such a way that a comfortable posture can be assumed, resulting in minimal fatigue
  • Look through the center of the lens to minimize distortion
  • Learn to read or scan by moving the head or the material or a combination of both

Learning sequences for monocular telescopes should include:

  • Learning to locate stationary objects through the telescope while the student is motionless
  • Learning to locate moving objects through the telescope while the student is motionless
  • Learning to locate moving objects while the student is in motion
  • Develop visual association, visual memory and spatial perception (where are the objects in space) so that the student can learn to cope with specific challenges, such as telescopic parallax, blind spots in the field, and speed blur


There are many other valuable nonprescription, low-vision devices that are not included in these kits, such as various hand magnifiers, focusable stand magnifiers, head-borne nonprescription aids, clip-on loupes for near vision, and a large variety of other monocular and binocular distance-vision devices in various magnification ranges and styles to fit individual needs.

This is why it is very important, whenever possible, to obtain a comprehensive low-vision evaluation for all visually impaired students to ensure that the widest variety of low-vision devices is considered. The comprehensive low-vision evaluation will also provide important information to the teacher or mobility specialist about the students etiology, diagnosis, prognosis, stability of the eye disease, the refractive error, visual fields, and the adequacy of visual function.

In California allowing students to try nonprescription magnifiers or monocular devices, or giving them other nonprescription devices without conferring with an eye doctor, does not constitute the practice of optometry any more than giving someone over-the-counter pain medication for a headache such as Tylenol would constitute the practice of medicine.

ENVISION I & II are certainly not panaceas, but they are great starts. They fill a real need in the area of low vision education and rehabilitation.

 

Comprehensive Low Vision Assessment

A regular eye exam concentrates on diagnosing eye disease and correcting visual acuity with regular lenses. A low vision exam focuses on using specialized low vision devices to enhance remaining vision. Low vision cannot be restored to normal vision. The person with low vision requires a functional vision assessment to evaluate vision functioning and the effect it has on daily living activities, such as reading and moving about safely.

A comprehensive low vision assessment includes a multidisciplinary approach to vision services. The eye exam uses special techniques and equipment to assess visual functioning. It involves multiple visits and the exam takes longer to administer. In addition to services from an ophthalmologist and/or optometrist, a comprehensive low vision exam team may commonly involve, but is not limited to, a psychologist, social worker, rehabilitation counselor, teacher, orientation and mobility instructor, and low vision device technician. The purpose of the exam is to help people with low vision gain a sense of independence and learn to compensate for their vision loss.

In order to conduct a comprehensive low vision assessment, there must be access not only to a multiple disciplinary team of professionals but also a large variety of low vision devices, including such optical devices as magnifiers and telescopes, nonoptical devices (i.e.) writing guides, talking calculators, closed circuit television, and computer screen readers.

 

Locating A Low Vision Specialist in Your Area

Only about five percent of all eye doctors specialize in low vision. You may contact the American Foundation for the Blind (AFB)(Outside Source) for information toll free at 800-232-5463. You may also contact the California Optometric Association(Outside Source) toll free at 800-877-5738. The California Academy of Ophthalmology(Outside Source) can be contacted toll free at 800-443-9370 to locate an eye doctor who specializes in low vision . A list of Optometrists who have earned special recognition as diplomats in low vision is available by contacting the American Academy of Optometry(Outside Source) at 301-984-1441.

 

California Low Vision Clinics and Centers

California Pacific Medical Center

Department of Ophthalmology Low Vision Service

2340 Clay St

San Francisco, CA 94115

415-923-3945

 

Center for the Partially Sighted(Outside Source)

12301 Wilshire Blvd, Suite 600

Los Angeles, CA 90025

310-458-3501

 

Jules Stein Eye Institute(Outside Source)

Univ of California, Los Angeles

100 Stein Plaza

Los Angeles, CA 90024

310-825-5051

King-Drew Medical Center

12021 South Wilmington Ave

Los Angeles, CA 90059

310-603-4281

 

Loma Linda University Medical Center(Outside Source)

Dept of Ophthalmology

11370 Anderson Street, Suite 1800

Loma Linda, CA 92354

800-553-0774

 

Low Vision Clinic(Outside Source)

University of California, San Francisco

400 Parnassus Ave.

San Francisco, CA 94143

415-476-4713

 

Low Vision Clinic(Outside Source)

School of Optometry

University of California, Berkeley

Berkeley, CA 94720

510-648-5726

Marin Low Vision Clinic

930 Tamalpais Ave.

San Rafael, CA 94901

415-457-8890

 

Optometric Center of Los Angeles(Outside Source)

3916 South Broadway

Los Angeles, CA 90037

213-234-9137

 

Vista Center(formerly Peninsula Center for the Blind and Visually Impaired) (Outside Source)

4151 Middlefield Road, Suite 101

Palo Alto, CA 94303

415-858-0202

 

SF Lighthouse for the Blind(Outside Source)

Low Vision Clinic

214 Van Ness Ave.

San Francisco, CA 94102

415-431-1481

 

Scripps Memorial Hospital(Outside Source)

Partial Vision Center

9888 Genesee Ave.

La Jolla, CA 92037

619-457-6571

 

Society for the Blind(Outside Source)

Low Vision Clinic

2750 24th Street

Sacramento, CA 95818

916-452-8271

 

Southern California College of Optometry(Outside Source)

Low Vision Clinic

2575 Yerba Linda Blvd.
Fullerton, CA 92631

714-449-7415

 

Stanford University(Outside Source)

Low Vision Service

300 Pasteur Drive

Palo Alto, CA 94305

415-723-5984

 

University of California, Davis(Outside Source)

Low Vision Service

1611 Alhambra Blvd.

Sacramento, CA 95816

916-734-6602

Vision Care Center

1045 S Street

Fresno, CA 93720

559-486-2000

 

OTHER CALIFORNIA AGENCY LINKS FOR LOW VISION SERVICES

 

California Department of Health Services(Outside Source)

PO Box 942732 MS-486

Sacramento, CA 94234-7320

(916) 327-6989

California Department of Mental Health(Outside Source)

1600 9th Street, Room 151

Sacramento, CA 95814

(916) 654-2309

 

California Department of Rehabilitation(Outside Source)

P.O. Box 944222

Sacramento, CA

94244-2220

(916) 263-8981

 

California Department of Social Services(Outside Source)

744 P Street

Sacramento, CA 95814

(916) 657-3667

 

State of California Home Web Page(Outside Source)

 

ADDITIONAL NATIONAL LOW VISION INTERNET RESOURCES

Note: The low vision clinics and Web resources listed here represent only a small sample of those available and in no way constitute an endorsement or recommendation by the California Department of Education for any of their services or products.
 

Low Vision Gateway(Outside Source)

National Association for the Visually Handicapped(Outside Source)

NYISE Low Vision Resource Center(Outside Source)

Questions:  Jonn Paris-Salb | jparissalb@cde.ca.gov | 916-323-2202