Sight is an ability that allows us not only to perform many of our functions of daily living, but it is also a sense that allows us to enjoy the things we do. For children who are unable to see, or who have limited sight, performing daily living functions, and growing up as a healthy, happy child may seem like daunting tasks. However, a visually impaired child can lead a productive, joyful life with the help of parents, educators and health professionals who understand the special needs of such a child.
If you think your child may have a visual impairment, or if your child has recently been diagnosed with a visual impairment, the following information will help you understand visual impairment in children and to link you with other sources of information and support.
The visual system, including the eye, that provides for sight is a complex grouping of nerves, muscles, tissue and fluid. Because this system is so complex, any defect or injury to the eye itself, the muscles that support the eye, or the nerves surrounding the eye, including the optic nerve, can result in visual impairment A complete illustration of the eye can be found at NEI. The eye itself is made up of the:
- cornea: transparent, outer layer of eye through which light passes and is the chief refractive medium for the eye, focusing light rays onto the retina
- anterior chamber: space in front of pupil and lens, through which light also passes
- pupil: hole in front of the lens which serves to control the amount of light that passes into the eye
- lens: refracts light, and can vary its shape depending on the amount of light
- iris: pigmented area surrounding pupil
- vitreous humor: fluid that fills the eye ball, or globe, 99% water, functions to refract light
- retina: located in the back lining of the eye ball, is made up of photoreceptor cells that transform images seen to nerve impulses carried by the optic nerve to the brain; the center of the retina holds the region of greatest visual acuity of form and color
- optic nerve: located at the back of the eye ball, connects to the visual center of the brain.
- sclera: white, rubber-like protective globe, what makes up the white eye ball
Common Causes of Visual Impairment
There are varying degrees of visual impairment, from low vision to blindness. As described, the eye and its system is so complex that any interference or dysfunction in the process could result in a visual impairment. Some common causes of a visual impairment include:
- injuries to eye, optic nerve, or visual area of brain
- illness or infection that affects the visual system
- metabolic disorders (e.g. diabetes)
- inherited genetic defects or syndromes
- congenital abnormalities
- exposure to infection prenatally
Types of Visual Impairments
There are many types of visual impairments that affect different parts of the eye or visual system. A comprehensive list of various conditions associated with visual impairment can be found at NYISE, or for comprehensive information on childhood visual impairments and links regarding specific diseases, go to Growing Strong.
- Anophthalmia/Microphthalmia (A/M): A/M is the absence of, or remnant of the globe and ocular tissue from the orbit; A/M may affect one eye with the other eye being normal, or both eyes, resulting in blindness. A/M can be congenital or acquired after birth. The causes of A/Mmay include inherited genetic defects, chromosomal abnormalities, trauma or exposure to toxins prenatally.
- Cataracts: condition affecting the lens of the eye where clouding occurs preventing light from passing through; may be present at birth or develop later.
- Retinopathy of Prematurity(POM): condition of premature infants who require extensive oxygen therapy after birth, where the retina becomes damaged and cannot respond appropriately to light.
- Retinitis Pigmentosa: condition affecting retina where an abnormal accumulation of pigmentation occurs impairing vision, results in a progressive loss of peripheral vision.
- Retinoblastoma: a tumor of the eye which often requires removal of the entire eye resulting in total blindness. It may also occur only in one eye, leaving the person with normal vision in the other eye.
- Leber’s Congenital Amaurosis:LCA is a degenerative condition of the retina. Many children with LCA have some vision; others are totally blind.
- Imbalance of eye muscles or nerves associated with the eye
- Strabismus: condition of uncoordinated eye movements including esotropia, or “crossed-eyes”, exotropia, or “wall-eyes,” and amblyopia, or “lazy eye”
- Nystagmus: condition of atypical eye movements or jerks
- Myopia (Near-sightedness):difficulty seeing things in the distance
- Hyperopia (far-sightedness):difficulty seeing things very close
Developmental Considerations for the Visually Impaired Child
Your visually impaired child may need direct teaching various skills and experiences to maximize his or her growth and development. The following is a list of developmental considerations for your visually impaired child. For a comprehensive listing of this information, along with resources and suggestions for each consideration go to SASKED.
- Sensory-motor skills (sitting, crawling, walking, balancing, developing fine and gross motor skills)
- Concept development (body image, environment, sexuality, gender awareness, space, time, position)
- Communication (exposure to braille books, learn name and pronounce, listening skills, language skills)
- Orientation and mobility (body awareness, spatial awareness, auditory awareness, sighted guide techniques)
- Daily living skills (dressing, cleaning, personal hygiene, using the telephone)
- Self-concept and socialization (displaying appropriate behavior, communicating one’s needs, playing)
- Knowledge of the eye condition (basic functions of the eye, name, cause and implications of eye condition, eye care)