Nyctalopia or night blindness refers to the medical condition in which a specific person is not able to see in relatively low light making it a severe eye disease. Night blindness may be found to exist from the birth or may be caused by an injury to that person or by a condition in which the person is not able to get the proper nourishment he desires suppose he is not able to get vitamin a in adequate amount is known as malnutrition, this stage is also likely to make him night blind. This disease can be thus explained as in-adequate adaption to the darkness.
What Is Night Blindness
Retinitis pigmentosa is the most common cause of night blindness.It is an disorder in which the rod cells found in the ratina of an individual loose their ability to respond to the light. The patients that suffer from this genetic condition have priogressive night blindness and as a result their sight in the day time may also be affected.
The second one is contigenital stationary nyctalopia, in it the rod cells found in the retina of the specific person do not work at all or work at a very minute level. Another among the cause of night blindness is the deficiency of vitamin a or the deficiency of retinol that is found in the fish oils , the liver and the dairy products.
Outer area of the retina of the eyes is made up of more rod cells then the cone cells. The loss of the peripheral sight may often result in nyctalopia. The people suffering from nyctalopia not only view badly at the night but also need some time for their eyes to adjust according to the brightly lit lamps and dim lit lamps. Contrast vision may even be greatly reduced in that case.
The rod cells contain a certain pigment called rhodopsin. When light rays fall on this pigment, it undergoes a series of confirmational changes that ultimately generate the electric signals that are carried out to the brain of that specific person by the optical nerve. In the absence of the light rays this rhodopsin is generated again and gets synthesized by the body from vitamin a or retinol that is why its deficiency may cause nyctalopia.
The reverse problem is the inability to see in the bright rays of light and it is a rare disease known as hemeralopia.