Not all visual impairments are the same, although the umbrella term “visual impairment” may be used to describe generally the consequence of an eye condition or disorder.
The eye has different parts that work together to create our ability to see. When a part of the eye doesn’t work right or communicate well with the brain, vision is impaired.
Most of us are familiar with visual impairments such as near-sightedness and far-sightedness. Less familiar visual impairments include:
- strabismus, where the eyes look in different directions and do not focus simultaneously on a single point;
- congenital cataracts, where the lens of the eye is cloudy;
- retinopathy of prematurity, which may occur in premature babies when the light-sensitive retina hasn’t developed sufficiently before birth;
- retinitis pigmentosa, a rare inherited disease that slowly destroys the retina;
- coloboma, where a portion of the structure of the eye is missing;
- optic nerve hypoplasia, which is caused by underdeveloped fibers in the optic nerve and which affects depth perception, sensitivity to light, and acuity of vision; and
- cortical visual impairment (CVI), which is caused by damage to the part of the brain related to vision, not to the eyes themselves.
Because there are many different causes of visual impairment, the degree of impairment a child experiences can range from mild to severe (up to, and including, blindness). The degree of impairment will depend on:
- the particular eye condition a child has;
- what aspect of the visual system is affected (e.g., ability to detect light, shape, or colour; ability to see things at a distance, up close, or peripherally); and
- how much correction is possible through glasses, contacts, medicine, or surgery.
The term “blindness” does not necessarily mean that a child cannot see anything at all. A child who is considered legally blind may very well be able to see light, shapes, colours, and objects (albeit indistinctly). Having such residual vision can be a valuable asset for the child in learning, movement, and life.