Blindness is the inability to see anything, even light. If you’re partially blind, you have limited vision. For example, you may have blurry vision or the inability to distinguish the shapes of objects. Complete blindness means that you can’t see…
Blindness is the condition of poor visual perception. Various scales have been developed to describe the extent of vision loss and define blindness. Total blindness is the complete lack of form and visual light perception and is clinically recorded as NLP, an abbreviation for “no light perception.”
Blindness is frequently used to describe severe visual impairment with some remaining vision. Those described as having only light perception have no more sight than the ability to tell light from dark and the general direction of a light source. The World Health Organization defines low vision as visual acuity of less than 20/60, but equal to or better than 20/200, or visual field loss to less than 20 degrees, in the better eye with best possible correction.
Blindness is defined as visual acuity of less than 20/400, or a visual field loss to less than 10 degrees, in the better eye with best possible correction. As of 2012, there were 285 million visually impaired people in the world, of which 246 million had low vision and 39 million were blind. Most people with poor vision are in the developing world and are over the age of 50 years.
According to WHO estimates, the most common causes of blindness (excluding refractive error) around the world in 2002 were:
- Cataracts (47.9%)
- Glaucoma (12.3%)
- Age-related macular degeneration (8.7%)
- Corneal opacification (5.1%)
- Diabetic retinopathy (4.8%)
- Childhood blindness (3.9%)
- Trachoma (3.6%)
- Onchocerciasis (0.8%)
Can a stroke lead to blindness?
It is true that stroke can cause blindness in one eye. Stroke, also called cerebrovascular accident (CVA), is lack of blood in the brain and rapid loss of brain function. It is easy to lead to eye vision problems. Blurred vision, glaucoma, cataracts, even blindness.
What causes blindness at birth?
The causes of SVI and blindness may be prenatal, perinatal, and postnatal. Congenital anomalies such as anophthalmias, microphthalmia, coloboma, congenital cataract, infantile glaucoma, and neuro-ophthalmic lesions are causes of impairment present at birth.
What causes color blindness?
Color blindness affects a significant percentage of the population. There is no actual blindness but there is a deficiency of color vision. The most usual cause is a fault in the development of one or more sets of retinal cones that perceive color in light and transmit that information to the optic nerve.