Simple FactTinnitus is a medical condition where the patient experiences a ringing in the ears.

In-Depth FactTinnitus is a hearing symptom that

presents itself as a ringing or buzz in the ear. Tinnitus is commonly caused by hearing loss due to age, ear injury, or a circulatory system disorder. Since, tinnitus is a symptom, often times treating the cause can reduce the ringing or buzzing. (Mayoclinic.org)

Simple FactVitamin A deficiency is the leading, preventable cause of blindness in children in the world.

In-Depth FactVitamin A plays a vital role in

phototransduction, or the conversion of light into electrical signals that are sent from the eyes to the brain resulting in sight. (Wikipedia) Vitamin A deficiency (VAD), which means you do not have enough Vitamin A in your diet, leads to blindness in a quarter to half a million children, usually in poorer regions of the world (WHO.int).

Simple FactAnosmia is a condition where the olfactory sense, or smell, is diminished or non-existent.

In-Depth FactTypically a temporary problem,

anosmia is the lack of smell or, to put another way, the loss of your olfactory senses. Anosmia is usually caused by nasal congestion due to a cold or allergies, however injury to the head, smoking, nasal drug use and old age have all been shown to cause this disorder. (WebMD.com) You may also be born with this disorder in which case it is called Congenital Anosmia. (Wikipedia)