Visual Impairments - Assessments

Visual Impairments

Visual impairment is the consequence of a functional loss of vision, rather than the eye disorder itself. Eye disorders which can lead to visual impairments can include retinal degeneration, albinism, cataracts, glaucoma, muscular problems that result in visual disturbances, corneal disorders, diabetic retinopathy, congenital disorders, and infection.

The terms partially sighted, low vision, legally blind, and totally blind are used in the educational context to describe students with visual impairments. They are defined as follows:

Partially sighted - indicates some type of visual problem has resulted in a need for special education
Low vision - generally refers to a severe visual impairment, not necessarily limited to distance vision. Low vision applies to all individuals with sight who are unable to read the newspaper at a normal viewing distance, even with the aid of eyeglasses or contact lenses. They use a combination of vision and other senses to learn, although they may require adaptations in lighting or the size of print, and, sometimes, braille
Legally blind - indicates that a person has less than 20/200 vision in the better eye or a very limited field of vision (20 degrees at its widest point) and
Totally blind students learn via braille or other non-visual media.

There is a wide range of visual impairments. People may be able to discern light, colors, or shapes. Some may be able to read by seeing clearly through one small area but have trouble getting around. Others may be able to see a whole area but have difficulty reading. Some have diseases which cause their visual acuity to fluctuate. The definition of visual impairment used in school settings considers the extent to which a student's vision affects learning and makes special methods or materials necessary.

The rate at which visual impairments occur in individuals under the age of 18 is 12.2 per 1,000. Severe visual impairments (legally or totally blind) occur at a rate of .06 per 1,000.

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Assessments

Assessments

There are several assessment instruments that are available to clinicians who assess students with visual impairment. Some of these are listed below.

Beyond Arms Reach: Enhancing Distance Vision (1992)
Authors: Smith, A., and O'Donnell, L. M.
Ages: Four years to adult
Stated Purpose: To assist a child in becoming more proficient in identifying and using visual cues.
Type of Instrument: Non-assessment focused teaching curriculum.
Comments: The Beyond Arms Reach: Enhancing Distance Vision program is a series of sequential lessons from which a child can build a visual foundation and develop skills. The child learns to identify cues, such as simple form discrimination, and develop more complex visual skills, such as distance and depth cues. The program covers basic visual-motor skills; feature, shape, and object formation; moving through the environment (position, distance, and depth cues); and increasing experiential knowledge through visual exploration.
Normative Data: The Beyond Arms Reach: Enhancing Distance Vision program is not an assessment tool, but rather a teaching curriculum. as such, normative data is not provided for determination of age appropriateness of skills level development.
Standardization: This program was designed specifically for students with visual impairment or multiple disabilities.
Adaptations: As Beyond Arms Reach: Enhancing Distance Vision is designed specifically for students with visual impairment or multiple disabilities, adaptations are not necessary.

Visual Assessment Procedure-Capacity, Attention, and Processing (VAP-CAP) (1992)
Author: Blanksby, D.C.
Ages: Five years and older
Stated Purpose: An assessment of visual functioning in an educational setting.
Type of Instrument: Criterion-referenced assessment instrument.
Comments: The Visual Assessment Procedure-Capacity, Attention, and Processing (VAP-CAP) has two levels: the Low Vision Assessment, and the Visual Processing Assessment (which considers visual perceptual and visual cognitive abilities). There are three scores to the VAP-CAP: Visual Processing Ability (what sense the child can make of what is seen), Visual Capacity (what the child can see), and Formal Visual Learning (visual cognition and visual motor coordination).
Normative Data: The VAP-CAP is a criterion-referenced assessment instrument that is focused on determining an individual's visual functioning skills, rather than determining age-appropriateness of the individual's skills in these areas.
Standardization: Standard administration and scoring procedures are appropriate, as the VAP-CAP was designed specifically for students with visual impairment or multiple disabilities.
Adaptations: As the VAP-CAP is designed specifically for students with visual impairment or multiple disabilities, adaptations are not necessary.

Visual Functioning Assessment Tool (1989)
Authors: Costello, K., Morgan, P. and Scheffers, W.
Ages: Five years and older
Stated Purpose: To measure functional vision in an educational setting.
Type of Instrument: Criterion-referenced assessment instrument.
Comments: The Visual Functioning Assessment Tool is a comprehensive visual functioning assessment tool covering appearance of eyes, basic responses, fixation, Tracking, Saccadic Movements, Scanning, Visual Field, Depth Perception, Eye-Hand Coordination, Eye-Foot Coordination, Visual Imitation and Memory, Visual Discrimination, Visual Perception, Concept of Self and Objects in Space, Pictures, Visual Environment, and Mobility. The Visual Functioning Assessment Tool is quite long, and is not meant to be administered to all students. Test materials describe tasks, and implications.
Normative Data: The Visual Functioning Assessment Tool is a criterion-referenced assessment instrument that is focused on determining an individual's visual functioning skills, rather than determining age-appropriateness of the individual's skills in these areas.
Standardization: Standard administration and scoring procedures are appropriate, as The Visual Functioning Assessment Tool was designed specifically for those with visual impairment or multiple disabilities.
Adaptations: As the Visual Functioning Assessment Tool is designed specifically for those with visual impairment or multiple disabilities, adaptations are not necessary.

Teller Acuity Cards (1988)
Authors: Not specified
Ages: Two years and older
Stated Purpose: To measure distance acuity in children two years and older.
Type of Instrument: Norm-referenced assessment instrument.
Comments: The Teller Acuity Cards are 17 28x51 cm. cards composed of vertical black and white stripes of various thickness providing approximate Snellen acuity equivalents of 20/20 to 20/2400 at a distance of 15 inches. Estimates are based on the direction of the individual's gaze toward a preferred pattern versus a uniform background.
Normative Data: The Teller Acuity Cards set is a criterion-referenced assessment tool designed to provide an accurate measure of distance acuity, rather than any normative information.
Standardization: The Teller Acuity Cards were designed specifically for those with visual impairment or multiple disabilities.
Adaptations: As the Teller Acuity Cards were designed specifically for those with visual impairment or multiple disabilities, adaptations are not necessary.

Reynell-Zinkin Scales: Developmental Scale for Young Visually Handicapped Children (1979)
Authors: Reynell, J. and Zinkin, P.
Ages: Birth to five years.
Stated Purpose: The aim is to enable professional people, concerned with young visually handicapped children, to have some guidelines for assessment and developmental advice.
Type of Instrument: Norm-referenced assessment instrument.
Comments: There are six scales to the Reynell-Zinkin Scales: Developmental Scale for Young Visually Handicapped Children, which are Social Adaptation (Self-Help), Sensorimotor Understanding, Exploration of Environment, Response to Sound and Verbal Comprehension, Expressive Language, and Communication. This instrument was designed for those with multiple impairment, not only visual impairment. Based upon the severity of the visual handicap, performance in each of the areas may be converted to an approximate age equivalent, which is reported in years and months. A new version of the Reynell-Zinkin Scales: Developmental Scale for Young Visually Handicapped Children is currently being reviewed for publication.
Normative Data: The Reynell-Zinkin Scales: Developmental Scale for Young Visually Handicapped Children has been re-evaluated psychometrically recently, and a manual with new developmental age levels has been published by the Bartimeus Foundation, which can be contacted at P.O. Box 1003, 3700 BA Zeist, The Netherlands. The new age levels address complaints about the original data about overestimating the abilities of children with visual impairment.
Standardization: Standard procedures for administration and scoring are appropriate, as the Reynell-Zinkin Scales: Developmental Scale for Young Visually Handicapped Children was designed specifically for students with visual impairment or multiple disabilities.
Adaptations: As the Reynell-Zinkin Scales: Developmental Scale for Young Visually Handicapped Children was designed specifically for those with visual impairment or multiple disabilities, adaptations are not necessary.