Severe Vision Loss

Degrees In addition to the varying types of vision impairment and blindness, there are also varying degrees, the least of which is mild vision loss, defined as 20/30 to 20/60 vision with best possible lens correction. The next level, moderate vision loss (also known as moderate low vision), ranges from 20/70 to 20/160. Severe vision loss (aka severe low vision) is the third on the scale, ranging from 20/200 to 20/400. Fourth is profound vision loss (20/500 to 20/1,000), then near total blindness (20/1,000 or less). Total blindness occurs when there is no light perception at all (Low Vision, 2015).

Causes

Vision loss has numerous causes, the most common of which are congenital vision loss or blindness, macular degeneration, glaucoma, cataracts, diabetic retinopathy, and trachoma. Congenital vision loss or blindness occurs before or at birth, caused by any number of factors from genetics to a maternal infection. Diseases such as cataracts and glaucoma are typically seen in older adults, but can occur at any age. Cataracts cloud all or part of the lens, affecting the ability

For example, the sense of object permanence is established a year later than sighted children as blind children can’t understand this concept until he or she reaches for an object based on sound cues. Furthermore, because the child can’t see the result of their actions, he is “not be motivated to action” and “may not understand his ability to cause things to happen or to retain pleasurable stimuli (Strickling, N.D.)”. Also, a child will not know how to manipulate or line up objects if they can’t see how it’s done. This affects the child’s sense of constancy. Additionally, the child has difficulty with the concept of similarities and differences (classification). While comparing sizes causes no problems, extensive experience with same and different objects is necessary for the student to