Tag Archives: retinal disease

Types of Blindness

19 Oct

Blindness is the condition where one lacks visual perception due to physiological or neurological factors. 

Complete Blindness:

Complete or 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 residual vision.

Complete blindness causes complete darkness in the affected person’s sight. There is no perception of light, color, shape or movement.

Complete blindness, though rare, can be caused by any type of retinal detachment or damage to the optic nerve or a disease that attacks the central nervous system, such as brain tumor or a stroke.

Legal Blindness

Legal blindness is defined as having equal to or worse than a 20/200 visual acuity in the better eye with the best correction possible.

Legal blindness typically indicates that the central vision is lost while the peripheral vision is usually intact. Patients are usually able to function to a certain extent.

This means that a legally blind individual would have to stand 20 feet (6.1 m) from an object to see it, with corrective lenses and with the same degree of clarity as a normal sighted person could from 200 feet (61 m). People with average acuity, who nonetheless have a visual field of less than 20 degrees (the norm being 180 degrees), are also classified as being legally blind. 

Colour Blindness

People who suffer from Colour blindness, also called dyschromatopsia, are unable to distinguish between certain colors.

This type of blindness usually affects men and the most common form of color blindness is red-green color blindness. Color blindness is almost always present since birth and is usually caused by the presence of a defective gene in the X chromosome. 

Night Blindness

Night blindness is vision impairment that occurs at night or when the surrounding light is dim.

It does not generally result in a complete lack of vision, but significantly impairs vision. People with night blindness often have difficulty driving at night or seeing stars. These factors include cataracts, birth defects, Vitamin A deficiency or a retinal disease called Retinitis Pigmentosa.

Signs of blindness in babies

Blindness in children is extremely rare and is very difficult to detect, especially in newborns.

Premature babies are more vulnerable to blindness. If a baby is born blind, it’s usually because of abnormalities during development, a hereditary disease, injury at birth or congenital infection that caused the damage. 

Image courtesy: 

http://bit.ly/qP9rFa

http://bit.ly/q6f5ar

%d bloggers like this: