Correct Option: D

Xerophthalmia is not a genetic disorder. Xerophthalmia is a severe drying of the eye surface caused by a malfunction of the tear glands. Also found in people with immune disorders, it occurs most commonly because of decreased intake or absorption of vitamin A. symptoms include night blindness and eye irritation. In addition to the eyes being very dry, there is a loss of lustre on their surface. At later stages, the corneas become soft , with increased opacity.