Question

The least distance of distinct vision for a young adult with normal vision is about:
(A). 25 m
(B). 2.5 cm
(C). 25 cm
(D). 2.5m

Answer 1

- Hint: A healthy human eye can have a clear vision from infinity to some point near the eye after that eye is unable to make the image or make it blurred. Distance of distinct vision is defined as the minimum distance between the eye lenses and the object to form a clear image.

Complete step-by-step solution -

For a normal human eye the least distance of distinct vision can
There are two terms to be considered:
1. Farthest point- The distance from the eyes up to which a normal eye can see clearly is called farthest point .For an adult it is up to infinity i.e. eyes can see up to infinite distance.
2. Near point or least distinct vision - it is the distance from the eyes up to which eyes can have a clear vision is called least distinct vision. It is about 25cms for a normal healthy eye.
Thus adult eyes can see the object from infinity to 25cm.
Hence the correct option is “D”.

Additional information-
Optometry is the branch of medical science that involves examining the eyes and applicable visual systems for defects or abnormalities as well as the correction of refractive error with glasses or contact lenses and treatment of eye diseases.

Note- When the person grows older; his culinary muscles responsible for eye lens adjustments get weakened. As a result, accommodation power is reduced and hence the least distance of distinct vision is typically increased for older people (55years). This defect is called Presbyopia.