General Functioning<unk> s may take many forms and be of varying degrees.<unk>  acuity alone is not always a good predictor of an individual's function. Someone with relatively good acuity (e.g., 20/40) can have difficulty with daily functioning, while someone with worse acuity (e.g., 20/200) may function reasonably well if they have low<unk>  demands. It is also important to note that best-corrected<unk>  acuity differs from presenting<unk>  acuity; a person with a "normal" best corrected acuity can have "poor" presenting acuity (e.g. individual who has uncorrected refractive error). Thus, measuring an individual's general functioning depends on one's situational and contextual factors, as well as access to treatment. The American Medical Association has estimated that the loss of one eye equals 25%<unk>  of the<unk>  system and 24%<unk>  of the whole person; total loss of vision in both eyes is considered to be 100%<unk>  and 85%<unk>  of the whole person. Some people who fall into this category can use their considerable residual vision – their remaining sight – to complete daily tasks without relying on alternative methods. The role of a low vision specialist (optometrist or ophthalmologist) is to maximize the functional level of a patient's vision by optical or non-optical means. Primarily, this is by use of magnification in the form of telescopic systems for distance vision and optical or electronic magnification for near tasks. People with significantly reduced acuity may benefit from training conducted by individuals trained in the provision of technical aids. Low vision rehabilitation professionals, some of whom are connected to an agency for the blind, can provide advice on lighting and contrast to maximize remaining vision. These professionals also have access to non-visual aids, and can instruct patients in their uses. Mobility Older adults with<unk>  are at an increased risk of physical inactivity, slower gait speeds, and fear of falls. Physical activity is a useful predictor of overall well-being, and routine physical activity reduces the risk of developing chronic diseases and disability. Older adults with<unk>  (including glaucoma, age-related macular degeneration, and diabetic retinopathy) have decreased physical activity as measured with self-reports and accelerometers. The US National Health and Nutrition Examination Survey (NHANES) showed that people with corrected<unk>  acuity of less than 20/40 spent significantly less time in moderate to vigorous physical activity. Age-related macular degeneration is also associated with a 50% decrease in physical activity–however physical activity is protective against age-related macular degeneration progression. In terms of mobility, those with<unk>  have a slower gait speed than those without<unk> ; however, the rate of decline remains proportional with increasing age in both groups. Additionally, the<unk> ly impaired also have greater difficulty walking a quarter mile (400 m) and walking up stairs, as compared to those with normal vision. Cognitive Older adults with vision loss are at an increased risk of memory loss, cognitive<unk> , and cognitive decline. Social and Psychological Studies demonstrate an association between older adults with<unk>  and a poor mental health; discrimination was identified as one of the causes of this association. Older adults with<unk>  have a 1.5-fold risk of reporting perceived discrimination and of these individuals, there was a 2-fold risk of loneliness and 4-fold risk of reporting a lower quality of life. Among adults with<unk> , the prevalence of moderate loneliness is 28.7% (18.2% in general population) and prevalence of severe loneliness is 19.7% (2.7% in general population). The risk of depression and anxiety are also increased in the<unk> ly impaired; 32.2% report depressive symptoms (12.01% in general population), and 15.61% report anxiety symptoms (10.69% in general population). The subjects making the most use of rehabilitation instruments, who lived alone, and preserved their own mobility and occupation were the least depressed, with the lowest risk of suicide and the highest level of social integration. Those with worsening sight and the prognosis of eventual blindness are at comparatively high risk of suicide and thus may be in need of supportive services. Many studies have demonstrated how rapid acceptance of the serious<unk>  handicap has led to a better, more productive compliance with rehabilitation programs. Moreover, psychological distress has been reported to be at its highest when sight loss is not complete, but the prognosis is unfavorable. Therefore, early intervention is imperative for enabling successful psychological adjustment. Associated conditions Blindness can occur in combination with such conditions as intellectual disability, autism spectrum disorders, cerebral palsy, hearing<unk> s, and epilepsy. Blindness in combination with hearing loss is known as deafblindness. It has been estimated that over half of completely blind people have non-24-hour sleep–wake disorder, a condition in which a person's circadian rhythm, normally slightly longer than 24 hours, is not entrained (synchronized) to the lightdark cycle.
Visual impairment
Dyslexia
Vision disorder
Sexual dysfunction
Cognitive disorder
Cognitive deficit
Cortical blindness
Color blindness