A student is unable to see clearly the words written on the black board

• Human Eye & Colourful World (C10)

A student is unable to see clearly the words written on the black board placed at a distance of approximately 3 m from him. Name the defect of vision the boy is suffering from. State the possible causes of this defect and explain the method of correcting it.

Answer

Defect of vision: Myopia or short sightedness or near sightedness

Causes of myopia:

1. Excessive curvature of eye lens; eye lens becomes more converging
2. Elongation of eye ball

Methods of correction:

By the use of concave lens of suitable power or focal length the defect is corrected.