Causes of vision loss
Human beings now suffer many kinds of vision problems, and vision loss is the most serious one. Total vision loss means the absence of vision. This kind of vision problem can happen either acutely or chronically. In this case, vision loss can be divided into two parts. The first one is acute vision loss, which means the patient can not see anything suddenly, either temporarily or devastating. And the second part is chronic vision loss, in which the patient’s visual acuity becomes lower and lower gradually.
Ocular opacities are the major causes of acute vision loss
There are many causes for acute vision loss. The most common one is media opacity. Opacities of the refractive media of the eyes can cause a wide variety of eye problems, such as cataracts, glaucoma, corneal edema, hyphema and vitreous hemorrhage. Related ocular parts include cornea, anterior chamber, lens and vitreous humor. Among all these eye problems, cataracts and glaucoma are the leading causes of vision loss. They account for more than 50% of the total cases of vision loss, according to WHO statistics.
Retinal diseases and optic nerve disorders are possible reasons
Sudden vision loss can also be caused by some retinal diseases such as retinal detachment, macular disease, retinal vascular occlusions and central retinal artery occlusion. In addition, the optic nerve disease, functional disorder and visual pathway disorders may also cause certain degrees of vision loss. Sometimes, low oxygen supply for the eyes may cause temporarily vision loss. Underlying reasons for this condition include standing up suddenly, shock or infirm.
The definition of chronic blindness and its reasons
People with chronic vision problems may suffer gradual vision loss day by day. Usually if the patient can’t tell light from dark or just can tell the general direction of a light source, they are diagnosed as blind. In addition, many other conditions can be defined as blindness, e.g. central visual acuity is 20/200 but less in the better eye with corrective glasses, or central visual acuity is more than 20/200 but the widest diameter of the visual field is less than 20 degrees in the better eye. Glaucoma and macular degeneration are the leading causes of chronic vision loss.
How to live with vision loss?
In the United States, there are now 25 million people who suffer from different degrees of vision loss. It is very important for this group to find ways to finish route daily tasks, e.g. reading, writing, travelling, enjoy recreational sports and games and so on. In fact, they can get help from a lot of assistant devices, such as large print books and newspapers, a long white cane, a guide dog, and many low-vision optical and adaptive devices.
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