exam from DIFF

Question 1

Standard Observer:

Answer 1

An observer with a visual acuity that just allows px to distinguish letters with a limb width of 1’ arc.

Question 1

1st focal point F

Answer 1

The point on the optical axis such that object rays that meet or originate at this point will refract parallel to each other and to optical axis

Question 2

Hypermetropia

Answer 2

Second focal point falls behind the retina in the unaccommodated eye.

Question 3

Myopia

Answer 3

Second focal point falls in front of the retina in the unaccommodated eye.

Question 4

Minimum Angle of Resolution (MAR):

Answer 4

angular separation, usually in minutes of arc, between two points or lines at the resolution acuity limit.

Question 5

Near Point (MP)

Answer 5

Point conjugate with the retina when the eye is in its fully accommodated state

Question 6

Far Point (MR)

Answer 6

Object point conjugate with the retina in the unaccommodated eye.

Question 7

Accommodation

Answer 7

Increase in the Dioptric power of the eye with an effort to focus at near

Question 8

2nd focal point F’

Answer 8

The point on the optical axis , if object rays are parallel to each other and to the optical axis their corresponding image rays will intersect at F’

Question 9

Astigmatism

Answer 9

Difference in power between two perpendicular meridians.