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A Snellen chart, which is frequently used for visual acuity testing Acute visual loss is a rapid loss of the ability to see . It is caused by many ocular conditions like retinal detachment , glaucoma , macular degeneration , and giant cell arteritis , etc.
Visual or vision impairment (VI or VIP) is the partial or total inability of visual perception.In the absence of treatment such as corrective eyewear, assistive devices, and medical treatment, visual impairment may cause the individual difficulties with normal daily tasks, including reading and walking. [6]
Cortical blindness refers to any partial or complete visual deficit that is caused by damage to the visual cortex in the occipital lobe. Unilateral lesions can lead to homonymous hemianopias and scotomas. Bilateral lesions can cause complete cortical blindness and can sometimes be accompanied by a condition called Anton-Babinski syndrome. [26]
Age-related macular degeneration is a main cause of central blindness among the working-aged population worldwide. [6] As of 2022, it affects more than 200 million people globally with the prevalence expected to increase to 300 million people by 2040 as the proportion of elderly persons in the population increases.
Amsler grid, Chart 1 There are 7 types of Amsler grid charts. All charts measure 10 cm × 10 cm (3.9 in × 3.9 in), which when viewed at a distance of 33 cm (13 in) from the eye can be used to measure defects in the central 20 degrees of the visual field .
In NPCB survey (2001–2002) Corneal opacity was the 6th major cause of blindness in India, which accounts for 0.9% of total blind population. In the RAAB (Rapid Assessment of Avoidable Blindness) survey (2006–2007) Corneal opacity including Trachoma was mentioned as the second major cause of blindness, which accounts for 6.5% of total blindness.
Man, 31, suddenly went blind. Undiagnosed and uncontrolled type 2 diabetes was to blame. Blood sugar under control. Complicated cataract sugery.
Hysterical blindness (nowadays known as conversion disorder), the appearance of neurological symptoms without a neurological cause. Inattentional blindness or perceptual blindness, failing to notice some stimulus that is in plain sight. Motion blindness, a neuropsychological disorder causing an inability to perceive motion.