The most common causes of visual impairment globally are uncorrected refractive errors (43%), cataracts (33%), and glaucoma (2%).[4] Refractive errors include near sighted, far sighted, presbyopia, and astigmatism.[4] Cataracts are the most common cause of blindness.[4] Other disorders that may cause visual problems include age related macular degeneration, diabetic retinopathy, corneal clouding, childhood blindness, and a number of infections.[5] Visual impairment can also be caused by problems in the brain due to stroke, prematurity, or trauma among others.[6] These cases are known as cortical visual impairment.[6] Screening for vision problems in children may improve future vision and educational achievement.[7] Screening adults without symptoms is of uncertain benefit.[8] Diagnosis is by an eye exam.The World Health Organization (WHO) estimates that 80% of visual impairment is either preventable or curable with treatment.[4] This includes cataracts, the infections river blindness and trachoma, glaucoma, diabetic retinopathy, uncorrected refractive errors, and some cases of childhood blindness.[9] Many people with significant visual impairment benefit from vision rehabilitation, changes in their environmental, and assistive devices.As of 2012 there were 285 million people who were visually impaired of which 246 million had low vision and 39 million were blind.[4] The majority of people with poor vision are in the developing world and are over the age of 50 years.[4] Rates of visual impairment have decreased since the 1990s.[4] Visual impairments have considerable economic costs both directly due to the cost of treatment and indirectly due to decreased ability to work.
Visual impairments may take many forms and be of varying degrees. Visual acuity alone is not always a good predictor of the degree of problems a person may have. 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 their visual demands are not great.The American Medical Association has estimated that the loss of one eye equals 25% impairment of the visual system and 24% impairment of the whole person;[20][21] total loss of vision in both eyes is considered to be 100% visual impairment and 85% impairment 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.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. These observations advocate the establishment and extension of therapeutic and preventative programs to include patients with impending and current severe visual impairment who do not qualify for services for the blind. Ophthalmologists should be made aware of these potential consequences and incorporate a place for mental health professionals in their treatment of these types of patients, with a view to preventing the onset of depressive symptomatology, avoiding self-destructive behavior, and improving the quality of life of these patients. Such intervention should occur in the early stages of diagnosis, particularly as many studies have demonstrated how rapid acceptance of the serious visual handicap has led to a better, more productive compliance with rehabilitation programs. Moreover, psychological distress has been reported (and is exemplified by our psychological autopsy study) to be at its highest when sight loss is not complete, but the prognosis is unfavorable.10 Therefore, early intervention is imperative for enabling successful psychological adjustment.
Visual impairments may take many forms and be of varying degrees. Visual acuity alone is not always a good predictor of the degree of problems a person may have. 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 their visual demands are not great.The American Medical Association has estimated that the loss of one eye equals 25% impairment of the visual system and 24% impairment of the whole person;[20][21] total loss of vision in both eyes is considered to be 100% visual impairment and 85% impairment 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.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. These observations advocate the establishment and extension of therapeutic and preventative programs to include patients with impending and current severe visual impairment who do not qualify for services for the blind. Ophthalmologists should be made aware of these potential consequences and incorporate a place for mental health professionals in their treatment of these types of patients, with a view to preventing the onset of depressive symptomatology, avoiding self-destructive behavior, and improving the quality of life of these patients. Such intervention should occur in the early stages of diagnosis, particularly as many studies have demonstrated how rapid acceptance of the serious visual handicap has led to a better, more productive compliance with rehabilitation programs. Moreover, psychological distress has been reported (and is exemplified by our psychological autopsy study) to be at its highest when sight loss is not complete, but the prognosis is unfavorable.10 Therefore, early intervention is imperative for enabling successful psychological adjustment.
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