Question

Night blindness is caused due to
(A) Hypermetropia
(B) Myopia
(C) Defective cornea
(D) Deficiency of rhodopsin in rods

Answer 1

Hint: The person is able to watch or see clearly at night just because of the presence of biological pigment which is commonly found in the rods of the retina and is a G-protein-coupled receptor (GPCR).

Complete answer:
Night blindness is caused due to the Deficiency of rhodopsin in rods. The pigment rhodopsin is commonly known to be extremely sensitive to light, and thus it helps to improve vision in low-light conditions. When rhodopsin is exposed to the light, it immediately photobleaches, which means there is a photochemical alteration of a dye taking place or a fluorophore molecule such that it permanently is unable to fluoresce.

Additional Information:
Night-blindness is defined as a condition making it difficult or impossible to visualize in relatively low light. It's an indication of several eye diseases. Nyctalopia is a disease that may exist from the birth of the child, or be caused by injury or malnutrition. It is easy that terms can be described as an insufficient adaptation to darkness. The most common reason for this disease i.e nyctalopia is retinitis pigmentosa, a disorder during which the rod cells within the retina gradually lose their ability to respond to the light. Patients affected by this type of genetic condition have progressive nyctalopia and eventually, their daytime vision can also be affected. In the X-linked congenital stationary nyctalopia, from birth, the rods either don't work at all, or work little or no, but the condition doesn't intensify.

So, the correct answer is option (D), ‘Deficiency of rhodopsin in rods ’.

Note: It was found that vitamin A deficiency can also lead to night blindness. Vitamin A, which is commonly known as retinol, plays a role in transforming nerve impulses into images in the retina. The retina is known to be the light-sensitive area in the back of your eye.