Lec 11: Spherical Ametropia and Astigmatism

Question 1

An unaccommodated eye which brings parallel pencils of rays from a
distant object to a sharp focus on the retina is said to be emmetropic.

Answer 1

emmetropia

Question 2

types of spherical ametropia

Answer 2

axial ametropia

refractive ametropia

Question 3

types of astigmatism

Answer 3

on axis astigmatism
off axis (oblique) astigmatism

Question 4

— the point conjugate with the fovea (M) of the unaccommodated eye

Answer 4

far point (Mr)!

Far-point is the furthest distance of clear vision ! Objects beyond the far-point appear blurred

Question 5

Amp=

Answer 5

K-B

Question 6

! Modeling refractive error: altered axial length

1 mm change in axial length produce a change in ametropia of what D

Answer 6

2.6 D

Question 7

0.37 mm changes in axial length alters the refractive

state by what?

Answer 7

1 D

Question 8

! Modeling refractive error: altered surface curvature

1 mm change in radius of curvature produce what D?

Answer 8

13 D change in ametropia

Question 9

_____ mm change in surface curvature alters the refractive state by one diopter

Answer 9

0.09 mm