Blindness, Causes, Signs and Symptoms, Diagnosis and Treatment. скачать в хорошем качестве

Blindness, Causes, Signs and Symptoms, Diagnosis and Treatment.

. Chapters 0:00 Introduction 2:01 Causes of Blindness 2:59 Symptoms of Blindness 3:42 Diagnosis of Blindness 4:02 Treatment of Blindness Visual impairment, also known as vision impairment or vision loss, is a decreased ability to see to a degree that causes problems not fixable by usual means, such as glasses.[1][2] Some also include those who have a decreased ability to see because they do not have access to glasses or contact lenses.[1] Visual impairment is often defined as a best corrected visual acuity of worse than either 20/40 or 20/60.[7] The term blindness is used for complete or nearly complete vision loss.[7] Visual impairment may cause difficulties with normal daily activities such as reading and walking without adaptive training and equipment.[2] The most common causes of visual impairment globally are uncorrected refractive errors (43%), cataracts (33%), and glaucoma (2%).[5] Refractive errors include near-sightedness, far-sightedness, presbyopia, and astigmatism.[5] Cataracts are the most common cause of blindness.[5] Other disorders that may cause visual problems include age-related macular degeneration, diabetic retinopathy, corneal clouding, childhood blindness, and a number of infections.[8] Visual impairment can also be caused by problems in the brain due to stroke, premature birth, or trauma, among others.[9] These cases are known as cortical visual impairment.[9] Screening for vision problems in children may improve future vision and educational achievement.[10] Screening adults without symptoms is of uncertain benefit.[11] Diagnosis is by an eye exam.[2] The World Health Organization (WHO) estimates that 80% of visual impairment is either preventable or curable with treatment.[5] This includes cataracts, the infections river blindness and trachoma, glaucoma, diabetic retinopathy, uncorrected refractive errors, and some cases of childhood blindness.[12] Many people with significant visual impairment benefit from vision rehabilitation, changes in their environment, and assistive devices.[2] As of 2015 there were 940 million people with some degree of vision loss.[6] 246 million had low vision and 39 million were blind.[5] The majority of people with poor vision are in the developing world and are over the age of 50 years.[5] Rates of visual impairment have decreased since the 1990s.[5] Visual impairments have considerable economic costs both directly due to the cost of treatment and indirectly due to decreased ability to work.[13]